Image Upload to Strapi via REST API with Next.js and Postman

Introduction to Media Upload in Strapi via REST API

Media uploads and image management is a key feature in modern applications. Strapi CMS offers flexible media upload capabilities through its REST API, making it an ideal tool for developers looking to integrate dynamic media handling into their projects. Thus, you can find the right asset and edit and reuse it in your websites.

In this tutorial, we will learn how to upload images to Strapi headless CMS using the REST API with Postman and Next.js. Using these tools, you’ll learn how to handle media efficiently in Strapi, equipping you with practical, scalable skills for content management.

Let's dive in!

Prerequisites

You will need to equip yourself with the following to proceed.

• Node.js runtime. Version 18 or higher.
• A code editor, preferably VS Code.
• Postman for API requests.

Outline

• Introduction to Media Upload in Strapi via REST API
• Prerequisites
• Outline
• Github Repo
• What You Will Build: An Image Upload System in Strapi
• Key Terms and Explanation
• Strapi Media Library and the Upload Plugin
• How to Upload Images in Strapi
• Create a Strapi Application
• Create a Next.js Application
• Upload Single or Multiple Images to Strapi
• Link an Image to an Existing Entry in Strapi
• Display Linked Images and Food Entries
• Upload a file at Entry Creation
• View, Delete, and Update Images
• Upload Image from an API controller in Strapi
• Image Upload to Strapi using Postman
• Conclusion

Github Repo

The source code for this project can be found here.

Also, in the repo above, you can find the images, in the images folder, we used for this tutorial.

What You Will Build: An Image Upload System in Strapi

To better understand this tutorial, we will build an image upload system that allows us to perform some image uploads and manipulations in Strapi.

Key Terms and Explanation

What is a REST API?

APIs are set of rules that allows different software applications to communicate with each other.

Representation State Transfer (REST) API, according to Wikipedia, is a software architectural style that was created to guide the design and development of the architecture for the World Wide Web.

In other words, with the REST API, we can make HTTP requests to servers to work on resources using the HTTP methods GET, POST, PUT, and DELETE.

What is Media Upload?

Media or file upload is very common in most technologies and providers, such as Nodejs, Laravel, Java, Cloudinary, AWS S3, etc., and is a fundamental aspect of web development. It is the transfer of files or media from a client machine to the server. This process is also a part of Strapi.

Strapi Media Library and the Upload Plugin

The Strapi Media Library allows the display of assets or files or via the media field of a Collection type. This plugin is activated by default.

On the other hand, the Upload plugin is responsible for powering the Media Library. You can use the Upload plugin API to upload files to Strapi or use the Media Library directly from the Strapi admin dashboard.

With the upload plugin, you can choose to upload files to the following:

• Local directory
• Amazon S3
• Cloudinary

Strapi maintains all the providers above. In the Strapi market place, you can find other providers such as Cloudimage, tools or Strapi plugins for image manipulation like Placeholder, Responsive image, Local Image Sharp, Image Color Palette, and so on. You can check out the Strapi market place here.

Strapi Media Library interface

Features of Strapi Media Library

• Extensive file format support
• Ability to search, sort, and filter files
• Preview of files
• Storage service integrations
• Automatic size optimization
• Live Editing
• Single or multiple uploads, etc.

To learn more, you can always visit the Strapi docs.

Types of Media in Strapi

Strapi supports various media uploads, including audio, files, images, and videos, as shown in the image below.

Types of Media in Strapi

For this tutorial, we will only examine Image Uploads. However, the methods discussed here should work for any other media type.

✋ NOTE: Strapi allows you to upload different kinds of files for uploading, as we will see shortly. However, we will use images for this tutorial.

Configuring the Strapi Upload Plugin

Strapi also allows us to configure the upload provider. This means that we can configure the file size, resolution, upload request timeout, responsive image size, and so on. With this, developers can have the freedom to customize and configure media uploads.

You can find information about configuring the Strapi Upload plugin here.

How to Upload Images in Strapi

There are different ways we can upload images in Strapi. They include:

• Upload Single/Multiple images in Strapi.
• Link an image by uploading it to an existing entry in Strapi.
• Link an uploaded image by its ID to an Existing Entry in Strapi.
• Upload upon entry creation (deprecated in Strapi 5; we will use another method).
• Upload a single file from an API controller in Strapi

We will see all these in action in the next sections.

Create a Strapi Application

Install Strapi v5

To install Strapi 5, run the command below:

npx create-strapi@latest

Or via Yarn.

yarn create strapi

We will give it the name strapi-backend. Please follow the prompts and answers below:

? What is the name of your project? strapi-backend
 
We can't find any auth credentials in your Strapi config.

Create a free account on Strapi Cloud and benefit from:

- ✦ Blazing-fast ✦ deployment for your projects
- ✦ Exclusive ✦ access to resources to make your project successful
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Start your 14-day free trial now!


? Please log in or sign up. Skip
? Do you want to use the default database (sqlite) ? Yes
? Start with an example structure & data? No
? Start with Typescript? Yes
? Install dependencies with npm? Yes
? Initialize a git repository? No

Start Strapi Application

If the installation is successful, CD into the Strapi project and run the command below to start the Strapi application.

npm run develop

Create Food Collection and Fields

We will first create our Food Collection Type.

Navigate to Content-Type Builder > Create a new collection type and enter the display name as Food.

Create Food Collection

Once you have entered the display name, click on Continue to create the following fields.

• name: This is the name of any food entry. It should be of type Short text.
• cover: This will represent the image of any food. It should be of type Media (Single media). Ensure that you click the ADVANCED SETTINGS tab and select images as the only allowed type of media.

Select Image as the only Allowed Media

Click on the Save button. If successful, this is what the Food collection should look like:

The Food Collection Type

Create Food Entries

The Food collection has been created, so let's add some entries. Create some entries with covers and also create some without covers, as shown below. For the latter without covers, we will add their covers by uploading them via the REST API using Next.js.

Create entries with and without covers

Enable Permission for Image Upload via API

We must first give permission to enable image upload via a REST API. To do this, navigate to Settings > Roles > Public, scroll down to the Upload plugin, and select the findOne, find and upload actions. Here is what they do:

• find: This will allow us to fetch all images uploaded to the Strapi. This endpoint for this is /api/upload/files
• findOne: This will allow us to fetch a specified image using its documentId. The endpoint for this is /api/upload/files/:id
• upload: This will allow us to upload images to Strapi. The endpoint for this is /api/upload/
• destroy: This will allow us to delete an image. The endpoint for this is /api/upload/files/:id.

! Enable Permission for Image Upload

To confirm this works, open the link http://localhost:1337/api/upload/files in your browser. You should see all the uploaded images and their data.

Fetch all images in Strapi backend

Enable API Permission for Food Collection

Enable API permissions to the Food collection, just like we did above. Click the Select all checkbox.

Enable API Permission for Food Collection

Bravo! We now have access to upload images, view images, delete images, and to view a specific image. We also have access to the Food collection. Now, let's move on to the frontend to start image uploading.

Create a Next.js Application

Install Next.js

Install Next.js by running the command below:

npx create-next-app@latest

Following the prompts after running the command above, we will name our project nextjs-frontend. See other prompts and answers below:

✔ What is your project named? nextjs-frontend
✔ Would you like to use TypeScript? Yes
✔ Would you like to use ESLint? No
✔ Would you like to use Tailwind CSS? Yes
✔ Would you like your code inside a `src/` directory? Yes
✔ Would you like to use App Router? (recommended) Yes
✔ Would you like to use Turbopack for next dev? No
✔ Would you like to customize the import alias (@/* by default)? No

Start The Next.js App

After successfully installing Next.js, the next step is to start the application. Run the command below:

npm run dev 

The command above will start our Next.js application on http://localhost:3000, as shown below.

Next.js Application

Install Additional Dependencies

We need to install react-toastify. This will help us with toasts or notifications.

npm i react-toastify

Ensure you CD into the directory of the Next.js app folder above, nextjs-frontend, before running the command above.

Create TypeScript Types

Inside the ./src/app folder, create a new file called Types.ts. This file will contain global types for our application, the ImageEntry and FoodEntry.

1// ./src/app/Type.ts
2
3// Image entry data types
4export interface ImageEntry {
5  id: number;
6  documentId: string;
7  name: string;
8  caption: string;
9  alternativeText: string;
10  url: string;
11}
12
13// food entry data types
14export interface FoodEntry {
15  id: number;
16  documentId: string;
17  name: string;
18  cover: ImageEntry;
19}

Create Next.js Components for our App

Before we begin creating the main functionalities of our application, let's create some starter components. Create a components folder inside the ./src folder. The components folder is where the components below will be created.

1. Create the SubmitButton Component Start by creating a submit button component. Create a SubmitButton.tsx inside the ./src/components folder.

1// ./src/components/SubmitButton.tsx
2
3"use client";
4
5import { useFormStatus } from "react-dom";
6
7export default function SubmitButton({ title }: { title: string }) {
8  const { pending } = useFormStatus();
9
10  return (
11    <button
12      type="submit"
13      aria-disabled={pending}
14      className="bg-black text-sm w-[100px] text-white px-3 py-1 rounded-lg"
15    >
16      {pending ? `${title}ing...` : title}
17    </button>
18  );
19}

The component above renders a submit button that disables itself and shows "ing" (e.g., "Submitting...") during form submission, using the useFormStatus hook. The "use client"; directive ensures it's client-side in Next.js.

2. Create MultipleOrSingleUpload Component This is where we will allow single or multiple image upload. Inside the ./src/components folder, create a MultipleOrSingleUpload.tsx file and add the following code.

1// ./src/components/MultipleOrSingleUpload.tsx
2
3"use client";
4
5import SubmitButton from "./SubmitButton";
6
7export default function MultipleOrSingleUpload() {
8
9  return (
10    <form className="flex rounded h-screen lg:w-full">
11      <div className="divide-y w-full">
12        <div className="w-full my-5">
13          <p className=" text-base lg:text-lg">Upload Multiple Files</p>
14          <span className="text-sm text-[#71717a]">
15            Here, you can upload one or more files!
16          </span>
17        </div>
18        <div className="flex flex-col pt-10 gap-y-7">
19          <input
20            type="file"
21            name="files"
22            className="text-sm text-[#71717a] p-5 lg:p-0  border"
23            multiple
24          />
25          <SubmitButton title="Upload" />
26        </div>
27      </div>
28    </form>
29  );
30}

The component above renders a form for uploading single or multiple files. It has an input field with name as files, for selecting files and a submit button. It uses the SubmitButton component, which we created above, for handling form submissions.

3. Create the LinkToSpecifiEntry Component This component will help us link an image to a specific entry by uploading it. Create a LinkToSpecificEntry.tsx file inside the ./src/components folder.

1// ./src/components/LinkToSpecificEntry.tsx
2
3"use client";
4
5import { useState } from "react";
6
7enum LinkType {
8  UPLOAD_FILE = "file",
9  GALLERY = "gallery",
10}
11export default function LinkToSpecificEntry() {
12  const [linkType, setLinkType] = useState<string>(LinkType.UPLOAD_FILE);
13
14  return (
15    <div>
16      <div className="w-full my-5">
17        <p className="text-lg font-semibold">Link to a Food</p>
18        <span className="text-sm text-[#71717a]">
19          Link to a specific entry and add a cover (image)
20        </span>
21      </div>
22      <div className="flex justify-between items-center w-full border">
23        <button
24          type="button"
25          onClick={() => setLinkType(LinkType.UPLOAD_FILE)}
26          className={`${
27            linkType === LinkType.UPLOAD_FILE
28              ? "bg-black text-white"
29              : "bg-white text-black"
30          } py-2 basis-1/2 px-3 transition-all duration-500`}
31        >
32          Link By Upload
33        </button>
34        <button
35          type="button"
36          onClick={() => setLinkType(LinkType.GALLERY)}
37          className={`${
38            linkType === LinkType.GALLERY
39              ? "bg-black text-white"
40              : "bg-white text-black"
41          } py-2 basis-1/2 px-3 transition-all duration-500`}
42        >
43          Link from Gallery
44        </button>
45      </div>
46    </div>
47  );
48}

The component above allows users to link to a specific food entry by uploading an image or selecting from a gallery (images already existing in Strapi admin dashboard). It uses useState to toggle between two button options (upload or gallery), dynamically changing their appearance based on the selected link type. The appearance is the form for each button option, which we will see shortly.

4. Create the LinkedImages Component This is where we will show food entries along with their linked images. Create a LinkedImages.tsx file inside the components folder and add the following code.

1// ./src/components/LinkedImages.tsx
2
3"use client";
4
5import { useState, useEffect } from "react";
6import { Food } from "../Types";
7
8export default function LinkedImages() {
9  const [foods, setFoods] = useState<Food[]>([]);
10
11  const getFoods = async () => {};
12
13  useEffect(() => {
14    getFoods();
15  }, []);
16
17  return (
18    <div className=" w-full">
19      <div className="w-full my-5">
20        <p className="text-lg font-semibold">Entries with Linked Images</p>
21        <span className="text-sm text-[#71717a]">
22          This is where you find all entries along with their linked images.
23        </span>
24      </div>
25    </div>
26  );
27}

The component above displays a section for entries with linked images and uses useState to manage a list of foods. The getFoods function is triggered via useEffect when the component mounts to fetch and set food data. Inside the getFoods function, we will invoke a service, which we will create shortly, to fetch food entries from the Strapi backend.

5. Create UploadAtEntryCreation Component The next component, the UploadAtEntryCreation, will allow us to upload an image upon entry creation. Although this is no longer possible in Strapi v5, we will achieve it using two steps.

🤚 NOTE In Strapi 5, creating an entry while uploading a file is no longer possible. The recommended steps are done in two steps, which we will see soon.

1// ./src/components/UploadAtEntryCreation.tsx
2
3"use client";
4
5import SubmitButton from "./SubmitButton";
6
7export default function UploadAtEntryCreation() {
8  return (
9    <form className="flex rounded h-screen lg:w-full">
10      <div className="w-full">
11        <div className="w-full my-5">
12          <p className=" text-base lg:text-lg font-semibold">
13            Upload a File at Entry Creation
14          </p>
15          <span className="text-sm text-[#71717a]">
16            Here, you can create an entry with an image!
17          </span>
18        </div>
19        <div className="flex flex-col pt-10 space-y-2">
20          <label htmlFor="cover">Food Name</label>
21          <input
22            type="text"
23            name="name"
24            placeholder="Name"
25            className="text-sm text-[#71717a] p-2 border"
26          />
27          <span className="text-sm text-[#71717a]">
28            Select the image for this entry!
29          </span>
30        </div>
31        <div className="flex flex-col pt-10 gap-y-7">
32          <span className="flex flex-col space-y-2">
33            <label htmlFor="cover">Cover</label>
34            <input
35              type="file"
36              name="files"
37              className="text-sm text-[#71717a] p-5 lg:p-0  border"
38            />
39            <span className="text-sm text-[#71717a]">
40              Here, you can upload two or more files!
41            </span>
42          </span>
43          <SubmitButton title="Upload" />
44        </div>
45      </div>
46    </form>
47  );
48}

The UploadAtEntryCreation component above renders a form that allows users to create an entry with an image upload during entry creation. It includes fields for the entry name and an option to upload one or more files. The SubmitButton component is imported and handles form submission.

6. Create Gallery Component This is where all uploaded images in the Strapi backend will be displayed. Create a Gallery.tsx file inside the components folder and add the following code.

1// ./src/components/Gallery.tsx
2
3"use client";
4
5import { useEffect, useState } from "react";
6import { ImageI } from "@/app/Types";
7
8export default function Gallery() {
9  const [images, setImages] = useState<ImageI[]>([]); // state to hold images
10  const [selectedImage, setSelectedImage] = useState<ImageI | null>(null); // for selected image
11  const [update, setUpdate] = useState<boolean> (false); // if image should be updated or not
12
13  // call service to fetch images
14  const handleFetchImages = async () => {};
15  
16  // function to close the update modal
17  const closeModal = () => {
18    setUpdate(false);
19  };
20
21  // function to delete an image using the delete service
22  const onDeleteImage = async (imageId: number) => {};
23
24  // fetch images upon mounting
25  useEffect(() => {
26    handleFetchImages();
27  }, []);
28
29  return (
30    <div className=" w-full divide-y">
31      <div className="w-full my-5">
32        <p className="text-lg font-semibold">Welcome to Gallery</p>
33        <span className="text-sm text-[#71717a]">
34          This is where all uploaded images can be found.
35        </span>
36      </div>
37    </div>
38  );
39}

The component above renders a gallery for managing uploaded images. It uses useState to handle images, selected images, and a modal state for updates. The handleFetchImages function is called inside useEffect when the component mounts to fetch the images. Functions for closing the modal and deleting an image are also defined but not implemented.

7. Create the TabsContainer Component This is where we will toggle between tabs to display each component created above. Create a TabsContainer.tsx file inside the components folder.

1// .src/components/TabsContainer.tsx
2
3"use client";
4
5import { ToastContainer } from "react-toastify";
6import "react-toastify/dist/ReactToastify.css";
7
8import MultipleOrSingleUpload from "./MultipleOrSingleUpload";
9
10import { useState } from "react";
11import LinkToSpecificEntry from "./LinkToSpecificEntry";
12import LinkedImages from "./LinkedImages";
13import Gallery from "./Gallery";
14import UploadAtEntryCreation from "./UploadAtEntryCreation";
15
16// tabs for image uploads and manipulations
17enum Tabs {
18  MULTIPLE_OR_SINGLE = "multipleOrSingle",
19  SPECIFIC_ENTRY = "specificEntry",
20  LINKED_IMAGES = "linkedImages",
21  ENTRY_CREATION = "entryCreation",
22  GALLERY = "gallery",
23}
24
25export default function TabsContainer() {
26  const [tab, setTab] = useState<string>(Tabs.MULTIPLE_OR_SINGLE);
27
28  return (
29    <div>
30      <ToastContainer />
31
32      <div className="flex flex-col lg:flex-row w-full h-full lg:p-10 gap-x-10 ">
33        <div className="lg:flex  lg:flex-col text-sm items-start h-screen basis-2/6 w-full pt-5 ">
34          <button
35            className={`${
36              tab == Tabs.MULTIPLE_OR_SINGLE
37                ? " px-5 lg:px-4 text-red-500 lg:text-inherit  bg-[#f4f4f5] "
38                : null
39            } px-4 py-2 rounded-lg text-left  w-full`}
40            onClick={() => {
41              setTab(Tabs.MULTIPLE_OR_SINGLE);
42            }}
43          >
44            Upload Multiple Files
45          </button>
46          <button
47            className={`${
48              tab == Tabs.SPECIFIC_ENTRY
49                ? " px-5 lg:px-4 text-red-500 lg:text-inherit  bg-[#f4f4f5] "
50                : null
51            } px-4 py-2 rounded-lg text-left  w-full`}
52            onClick={() => {
53              setTab(Tabs.SPECIFIC_ENTRY);
54            }}
55          >
56            Link to a Specific Entry
57          </button>
58          <button
59            className={`${
60              tab == Tabs.LINKED_IMAGES
61                ? " px-5 lg:px-4 text-red-500 lg:text-inherit  bg-[#f4f4f5] "
62                : null
63            } px-4 py-2 rounded-lg text-left  w-full`}
64            onClick={() => {
65              setTab(Tabs.LINKED_IMAGES);
66            }}
67          >
68            Linked Images
69          </button>
70          <button
71            className={`${
72              tab == Tabs.ENTRY_CREATION
73                ? " px-5 lg:px-4 text-red-500 lg:text-inherit  bg-[#f4f4f5] "
74                : null
75            } px-4 py-2 rounded-lg text-left  w-full`}
76            onClick={() => {
77              setTab(Tabs.ENTRY_CREATION);
78            }}
79          >
80            Upload at Entry creation
81          </button>
82          <button
83            className={`${
84              tab == Tabs.GALLERY
85                ? " px-5 lg:px-4 text-red-500 lg:text-inherit  bg-[#f4f4f5] "
86                : null
87            } px-4 py-2 rounded-lg text-left  w-full`}
88            onClick={() => {
89              setTab(Tabs.GALLERY);
90            }}
91          >
92            Gallery
93          </button>
94        </div>
95
96        <div className="h-screen w-full flex flex-col  gap-y-10 basis-4/6">
97          {tab === Tabs.MULTIPLE_OR_SINGLE ? (
98            <MultipleOrSingleUpload />
99          ) : tab === Tabs.SPECIFIC_ENTRY ? (
100            <LinkToSpecificEntry />
101          ) : tab === Tabs.LINKED_IMAGES ? (
102            <LinkedImages />
103          ) : tab === Tabs.ENTRY_CREATION ? (
104            <UploadAtEntryCreation />
105          ) : (
106            <Gallery />
107          )}
108        </div>
109      </div>
110    </div>
111  );
112}

The TabsContainer component above renders a tabbed interface for managing various upload and image-related tasks we have mentioned previously, using useState to control which tab is active. The component includes buttons for selecting tabs, such as "Upload Multiple Files" and "Gallery," and conditionally renders the corresponding content based on the selected tab. It also integrates the ToastContainer from react-toastify to display toasts or notifications.

Display All Created Components

We want all the tab components created above to be visible. Here are the steps we will take to achieve this:

• Step 1: Remove Default CSS Ensure you visit the ./src/app/global.css file and update it with the following code:

1@tailwind base;
2@tailwind components;
3@tailwind utilities;

By updating the above, we have removed any custom default CSS.

• Step 2: Render TabsContainer Component Update the code in the ./src/page.tsx file with the following:

1// ./src/app/page.tsx
2
3import TabsContainer from "./components/TabsContainer";
4
5export default function Home() {
6  return (
7    <div className="min-h-screen p-3 lg:p-20">
8      <div className=" lg:px-14 py-5">
9        <p className="text-2xl lg:text-4xl font-bold mb-4">
10          Image Upload to Strapi
11        </p>
12        <span className="text-slate-400">
13          Let's demonstrate image upload to Strapi Content types using the REST
14          API
15        </span>
16        <TabsContainer />
17      </div>
18    </div>
19  );
20}

This is what our app should look like

Tabs for our application

Create Server Actions for our App

The next step is to create Next.js server actions. These are asynchronous functions that are executed on the server.

With server actions, you can ensure that heavy computations and sensitive operations are performed securely on the server, reducing the load on the client.

Here are the server actions we will create: 1. Multiple or single upload server action: This will allow us to upload a single or multiple images to Strapi. 2. Link to a specific entry server action (link an already uploaded image and link by uploading an image) 3. Upload at entry creation server action 4. Update image server action

Before we proceed to do that, let's create some constants and default actions. Inside the ./src/app folder, create a file called actions.tsx and add the following code:

1"use server";
2
3const STRAPI_URL: string = "http://localhost:1337";
4
5// accepted image types
6const ACCEPTED_IMAGE_TYPES = [
7  "image/jpeg",
8  "image/jpg",
9  "image/png",
10  "image/webp",
11];
12
13// upload single or multiple images
14export async function uploadMultipleOrSingleAction(
15  prevState: any,
16  formData: FormData
17) {}
18
19// Upload an Image and link to an entry
20export async function LinkByUploadAction(
21  prevState: any,
22  formData: FormData
23) {}
24
25// Link an Uploaded image to an Entry by ID
26export async function linkFromGalleryAction(
27  prevState: any,
28  formData: FormData
29) {}
30
31// Upload image at entry creation
32export async function uploadAtEntryCreationAction(
33  prevState: any,
34  formData: FormData
35){}
36
37// update mage file info action
38export async function updateImageAction(
39  prevState: any, 
40  formData: FormData
41){}

In the code above, STRAPI_URL stores the base URL of the Strapi API, and ACCEPTED_IMAGE_TYPES is an array that lists the accepted image formats (JPEG, JPG, PNG, and WEBP) for file uploads. The "use server" directive ensures the code runs on the server side. We then created the server actions that our Next.js server will perform, which we will later modify.

🤚 NOTE We will update the server actions above later in this tutorial.

Create Services for Our App

Next, we will create services for our application. Services are reusable functions that communicate with other services or external systems and can be called anytime.

For this application, we will create 3 services: 1. Fetch Images Service: This will help fetch images from the Strapi backend. 2. Fetch Foods Service: This will help fetch food entries from the Strapi backend. 3. Delete image service: This will help delete an image from the Strapi backend.

Proceed to create a file called services.ts and add the following code.

1// ./src/app/services.ts
2
3
4const STRAPI_URL: string = "http://localhost:1337";
5
6export const fetchImages = async () => {
7  try {
8    // fetch images from Strapi backend
9    const response = await fetch(`${STRAPI_URL}/api/upload/files`);
10
11    // if response is not ok
12    if (!response.ok) {
13      const errorDetails = await response.text();
14      throw new Error(
15        `Error fetching images: ${response.status} ${response.statusText} - ${errorDetails}`
16      );
17    }
18
19    // return fetched images
20    const result = await response.json();
21    return result;
22  } catch (error: any) {
23    throw new Error(`Failed to fetch images: ${error.message}`);
24  }
25};
26
27export const fetchFoods = async () => {
28  try {
29    // fetch foods from Strapi backend
30    const response = await fetch(`${STRAPI_URL}/api/foods?populate=*`);
31
32    // if response is not ok
33    if (!response.ok) {
34      const errorDetails = await response.text();
35      throw new Error(
36        `Error fetching Foods: ${response.status} ${response.statusText} - ${errorDetails}`
37      );
38    }
39
40    // return fetched foods
41    const result = await response.json();
42    return result;
43  } catch (error: any) {
44    // throw new error
45    throw new Error(`Failed to fetch images: ${error.message}`);
46  }
47};
48
49export const deleteImage = async (imageId: number) => {
50  try {
51    // make a DELETE request using image id.
52    const response = await fetch(`${STRAPI_URL}/api/upload/files/${imageId}`, {
53      method: "DELETE",
54    });
55
56    // if response is not ok
57    if (!response.ok) {
58      const errorDetails = await response.text();
59      throw new Error(
60        `Error deleting food entry: ${response.status} ${response.statusText} - ${errorDetails}`
61      );
62    }
63  } catch (error: any) {
64    // throw new error
65    throw new Error(`Failed to delete entry: ${error.message}`);
66  }
67};

Here is what the following services above do:

• fetchImages: Retrieves all uploaded images from the Strapi backend by sending a GET request to the /api/upload/files endpoint. It processes the response, throwing errors if the request is unsuccessful, and returns the list of images in JSON format.
• fetchFoods: Retrieves all food entries from the Strapi backend, including any populated relationships, by sending a GET request to the /api/foods endpoint with a populate=* query parameter. It checks for errors, handles unsuccessful responses, and returns the data in JSON format.
• deleteImage: Deletes a specific image from the Strapi backend by sending a DELETE request to /upload/files/{imageId} using the image’s unique ID. If the deletion fails, it throws a custom error message.

Now that we have created the services let's implement them.

Upload Single or Multiple Images to Strapi

Now, let's modify the MultipleOrSingleUpload component and the uploadMultipleOrSingleAction to implement this.

We will do this in 2 steps:

1. Update the uploadMultipleOrSingleAction Server Action

Update the uploadMultipleOrSingleAction server action so as to invoke it in the MultipleOrSingleImageUpload component.

1// ./src/actions.ts
2...
3export async function uploadMultipleOrSingleAction(
4  prevState: any,
5  formData: FormData
6) {
7  try {
8    const response = await fetch(`${STRAPI_URL}/api/upload`, {
9      method: "post",
10      body: formData,
11    });
12
13    const result = await response.json();
14
15    if (result.error) {
16      return {
17        uploadError: result.error.message,
18        uploadSuccess: null,
19      };
20    }
21
22    return {
23      uploadError: null,
24      uploadSuccess: "Images uploaded successfully",
25    };
26  } catch (error: any) {
27    return {
28      uploadError: error.message,
29      uploadSuccess: null,
30    };
31  }
32}

Here is what the code above does:

• prevState: This is the previous state of the form submission, which contains properties uploadError and uploadSuccess. It's provided when useFormState is invoked.
• formData: This is an instance of the FormData API containing the actual form data that the user wants to upload, which in this case are images.
• The function sends a POST request to the Strapi endpoint /api/upload to upload images. The formData, from the upload, is passed as the body of the request. If there's an error in the response (like the upload failing), it returns an error message. If the upload is successful, it returns a success message.

2. Update the MultipleOrSingleUpload Component

Let's modify the MultipleOrSingleUpload component form to trigger the server action above.

1// .src/components/MultipleOrSingleImageUpload
2
3"use client";
4import { uploadMultipleOrSingleAction } from "@/app/actions";
5import { useFormState } from "react-dom";
6import { Ref, useRef } from "react";
7import SubmitButton from "./SubmitButton";
8import { toast } from "react-toastify";
9
10const initialState = {
11  uploadError: null,
12  uploadSuccess: null,
13};
14
15export default function MultipleOrSingleImageUpload() {
16  const [state, formAction] = useFormState(
17    uploadMultipleOrSingleAction,
18    initialState
19  );
20  const formRef = useRef<HTMLFormElement | null>(null);
21
22  if (state?.uploadSuccess) {
23    formRef?.current?.reset();
24    toast.success(state?.uploadSuccess);
25  }
26
27  return (
28    <form
29      ref={formRef}
30      action={formAction}
31      className="flex rounded h-screen lg:w-full"
32    >
33      <div className="divide-y w-full">
34        <div className="w-full my-5">
35          <p className=" text-base lg:text-lg">Upload Multiple Files</p>
36          <span className="text-sm text-[#71717a]">
37            Here, you can upload two or more files!
38          </span>
39        </div>
40        <div className="flex flex-col pt-10 gap-y-7">
41          <input
42            type="file"
43            name="files"
44            className="text-sm text-[#71717a] p-5 lg:p-0  border"
45            multiple
46          />
47          {state?.uploadError ? (
48            <span className="text-red-500">{state?.uploadError}</span>
49          ) : null}
50          <SubmitButton title="Upload" />
51        </div>
52      </div>
53    </form>
54  );
55}

Here is what we did in the code above:

• state: This object is created by useFormState, which tracks the state of the upload (whether there’s an error or success).
• The initial state, initialState, includes uploadError: null and uploadSuccess: null. They will be used to pass error and success messages between the uploadMultipleOrSingleAction server action and the form above.
• formAction: This function links to the uploadMultipleOrSingleAction server action and is triggered when the form is submitted.
• formRef: This is a reference to the form DOM element, created using useRef. It’s used to reset the form fields after a successful upload.
• The <input> element has the multiple attribute, which allows users to select more than one file at a time. The name="files" attribute is crucial because it matches the expected key when submitting files in the FormData.
• If state.uploadError contains a message, it will be displayed in red below the input field using a conditional rendering block.
• If the state.uploadSuccess contains a success message (indicating that the files were uploaded successfully), the form is reset by calling formRef.current.reset().
• Additionally, a toast notification is displayed using toast.success(state.uploadSuccess) to notify the user that the upload was successful.

When everything is set and done, we should be able to upload a single or multiple images to our Strapi backend. See the GIF below:

Single or Multiple Image upload

When we visit the Strapi backend, we should see the images we just uploaded.

Images in Strapi Backend

Link an Image to an Existing Entry in Strapi

Like we pointed out in the beginning, we will do this in two ways. One is to link to an already existing image in Strapi backend by its ID to an entry and the other is to upload an image and link to a specific food entry.

Method 1: Link an Image to an Entry in Strapi

When we click on the "Link to a Specific Entry" tab, we can see "Link by Upload" and "Link from Gallery". In this method 1, we will link by upload.

• Step 1: Update the LinkByUploadAction Server Action

1// ./src/actions.ts
2
3...
4export async function LinkByUploadAction(prevState: any, formData: FormData) {
5  try {
6    // Convert formData into an object to extract data
7    const data = Object.fromEntries(formData);
8
9    // Create a new FormData object to send to the server
10    const formDataToSend = new FormData();
11    formDataToSend.append("files", data.files); // The image file
12    formDataToSend.append("ref", data.ref); // The reference type for Food collection
13    formDataToSend.append("refId", data.refId); // The ID of the food entry
14    formDataToSend.append("field", data.field); // The specific field to which the image is linked, i.e., "cover"
15
16    // Make the API request to Strapi to upload the file and link it to the specific entry
17    const response = await fetch(`${STRAPI_URL}/api/upload`, {
18      method: "post",
19      body: formDataToSend,
20    });
21
22	// upload respone
23    const result = await response.json();
24
25    // Handle potential errors from the API response
26    if (result.error) {
27      return {
28        uploadError: result.error.message,
29        uploadSuccess: null,
30      };
31    }
32
33    // Return success if the upload and linking are successful
34    return {
35      uploadSuccess: "Image linked to a food successfully!",
36      uploadError: null,
37    };
38  } catch (error: any) {
39    // Catch any errors that occur during the process
40    return {
41      uploadError: error.message,
42      uploadSuccess: null,
43    };
44  }
45}

In the code above, prevState holds the previous state of the upload process. formData contains the form data submitted by the user, including the file and other necessary fields (files, ref, refId, and field). The ref represents the reference type for Food collection, which we will add as a hidden value in the form below. The refId represents the ID of the food entry. Then we have the field, which represents the cover field of the food entry that we want to link.

• Step 2: Create a Form for Linking by Upload We have to trigger the server action above. To do this, inside the ./src/components folder, create a folder called form. Inside the new form folder, create a file called LinkByUpload.tsx and add the following code:

1// ./src/components/LinkByUpload.tsx
2
3import { useEffect, useState } from "react";
4import { useFormState } from "react-dom";
5import { toast } from "react-toastify";
6import { LinkByUploadAction } from "@/app/actions";
7
8import SubmitButton from "@/components/SubmitButton";
9import { fetchFoods } from "@/app/services";
10import { FoodEntry } from "@/app/Types";
11
12// initial state
13const initialState = {
14  uploadError: null,
15  uploadSuccess: null,
16};
17
18export default function LinkByUpload() {
19  const [state, formAction] = useFormState(LinkByUploadAction, initialState);
20  const [foods, setFoods] = useState<FoodEntry[]>([]);
21
22  const handleFetchFoods = async () => {
23    const result = await fetchFoods();
24    setFoods(result?.data);
25  };
26
27  useEffect(() => {
28    handleFetchFoods();
29  }, []);
30
31  if (state?.uploadSuccess) {
32    toast.success(state?.uploadSuccess);
33  }
34
35  return (
36    <div className="w-full">
37      <form action={formAction} className="flex rounded w-full">
38        <div className="flex flex-col pt-10 gap-y-7 w-full">
39          <div className="flex flex-col space-y-2">
40            <label htmlFor="name">Food</label>
41            <select name="refId" className="border p-2 text-[#71717a] text-sm">
42              {foods.map((food) => {
43                return (
44                  <option key={food.id} value={food.id}>
45                    {" "}
46                    {food.name}
47                  </option>
48                );
49              })}
50            </select>
51            <span className="text-sm text-[#71717a]">
52              Select the food you want to add Image to
53            </span>
54            <div className="flex flex-col space-y-2 pt-10">
55              <label htmlFor="cover">Cover</label>
56              <input
57                type="file"
58                name="files"
59                className="text-sm text-[#71717a] border"
60              />
61              <span className="text-sm text-[#71717a]">
62                Select an image to link to a food
63              </span>
64            </div>
65
66            {state?.uploadError ? (
67              <span className="text-red-500">{state?.uploadError}</span>
68            ) : null}
69            <input type="hidden" name="ref" value="api::food.food" />
70            <input type="hidden" name="field" value="cover" />
71            <div className="pt-5">
72              <SubmitButton title="Link" />
73            </div>
74          </div>
75        </div>
76      </form>
77    </div>
78  );
79}

From the code above, we have the foods state that stores the list of food items fetched from the server, which will be displayed in the dropdown menu. In other words, the component fetches food items using fetchFoods and populates the dropdown <select> menu. With that, users can select a food item, upload an image, and submit the form. Note that we have some hidden values such as ref. This has a value of api::food.food, which is the reference type for the food collection. It also has the refId as the id value of any food selected. The form triggers the LinkByUploadAction server action to perform the actual file upload and linking.

• Step 3: Update the LinkToSpecificEntry component Now, we will have to update the LinkToSpecificEntry component to include the LinkByUpload form we created above. Head over to ./src/components/LinkToSpecificEntry.tsx and replace the content with the following code:

1// ./src/components/LinkToSpecificEntry.tsx
2
3"use client";
4
5import { useState } from "react";
6
7import LinkByUpload from "./form/LinkByUpload";
8
9// linking type
10enum LinkType {
11  UPLOAD = "upload",
12  GALLERY = "gallery",
13}
14
15export default function LinkToSpecificEntry() {
16  const [linkType, setLinkType] = useState<LinkType>(LinkType.UPLOAD);
17
18  return (
19    <div>
20      <div className="w-full my-5">
21        <p className="text-lg font-semibold">Link to a Food</p>
22        <span className="text-sm text-[#71717a]">
23          Link to a specific entry and add a cover (image)
24        </span>
25      </div>
26      <div className="flex justify-between items-center w-full border">
27        <button
28          type="button"
29          onClick={() => setLinkType(LinkType.UPLOAD)}
30          className={`${
31            linkType === LinkType.UPLOAD
32              ? "bg-black text-white"
33              : "bg-white text-black"
34          } py-2 basis-1/2 px-3 transition-all duration-500`}
35        >
36          Link By Upload
37        </button>
38        <button
39          type="button"
40          onClick={() => setLinkType(LinkType.GALLERY)}
41          className={`${
42            linkType === LinkType.GALLERY
43              ? "bg-black text-white"
44              : "bg-white text-black"
45          } py-2 basis-1/2 px-3 transition-all duration-500`}
46        >
47          Link from Gallery
48        </button>
49      </div>
50      {linkType === LinkType.UPLOAD ? <LinkByUpload /> : null }
51    </div>
52  );
53}

In the code above, the LinkToSpecificEntry component creates an interface where users can either upload a new image or (in the future, which we will see soon) choose one from a gallery to link to a specific food entry. The form interaction is handled through state changes and conditional rendering, with the actual file upload functionality delegated to the LinkByUpload component.

Now, let's test our code:

Link an image by uploading to an entry

Head over to the Strapi backend to see if this was successful.

Linked Image not Showing

As shown in the image below, the linked image for "Pizza" didn't show. Now click on the Pizza entry and click on the "Published" tab. There, you will find the linked image.

Linked Image Shows only on Published Tab or verion

This means that the entry was published directly after linking. This happens as a result of the Draft and Publish feature of Strapi. But we don't want this behaviour. So, let's disable Draft and Publish in Food collection.

• Disable Draft and Publish for Food Collection Click on the Content-Type Builder and click on the Edit button for Food collection. Once the modal opens up, click on the ADVANCED SETTINGS tab and disable Draft and Publish. Ensure that you also click the Finish button and wait for the server to restart.

Disable Draft & publish

Once that is done, we can now see the linked image for Pizza!

Linked Image is now displayed

We can now proceed to link an already uploaded image to an existing entry.

Method 2: Link an Already Uploaded Image to an Existing Entry in Strapi

The next method would be to link an already uploaded image in the Strapi backend. In other words, we want to link using an image ID. To do this, we have to fetch images in the Strapi backend, thanks to the fetchImages service.

• Step 1: Configure Next.js For Image Links Since we will be displaying images uploaded to the Strapi backend, which is an external source, we need to protect our application from malicious users; configuration is required in order to use external images. Locate the ./next.config.mjs file and replace the content with the following code:

1/** @type {import('next').NextConfig} */
2const nextConfig = {
3    images: {
4        remotePatterns: [
5            {
6                hostname: "localhost"
7            }
8        ]
9    }
10};
11
12export default nextConfig;

With this, we have configured localhost to be a secure link to our images.

• Step 2: Update LinkFromGallery Server Action Update the LinkFromGalleryAction action with the following code:

1// ./src/app/actions.ts
2
3...
4export async function linkFromGalleryAction(
5  prevState: any,
6  formData: FormData
7) {
8  try {
9    const data = Object.fromEntries(formData);
10
11    const response = await fetch(`${STRAPI_URL}/api/foods/${data?.refId}`, {
12      method: "PUT",
13      headers: {
14        "Content-Type": "application/json",
15      },
16      body: JSON.stringify({
17        data: {
18          cover: data?.imageId,
19        },
20      }),
21    });
22
23    const result = await response.json();
24
25    if (result.error) {
26      return {
27        uploadError: result.error.message,
28        uploadSuccess: null,
29      };
30    }
31    return {
32      uploadSuccess: "Image linked to a food successfully!",
33      uploadError: null,
34    };
35  } catch (error: any) {
36    return {
37      uploadError: error.message,
38      uploadSuccess: null,
39    };
40  }
41}

In the code above, we updated the LinkFromGallery server action. It takes parameters prevState that hold the previous state of the form. formData contains the form data submitted by the user, including the refId (food ID) and imageId (selected image ID).

The Object.fromEntries(formData) converts the form data from the FormData format into a standard object for easier manipulation. The API request is sent to STRAPI_URL/api/foods/${data?.refId} to update the specific food entry with the selected image.

The body of the request contains the new image's ID (imageId) to be set and linked as the food's cover image.

• Step 3: Create a Form to Link by Gallery Inside the ./src/components/form folder, create another file called LinkByGallery.tsx and add the following code:

1// ./src/components/form/LinkByGallery.tsx
2
3import { useEffect, useState, useRef } from "react";
4import { useFormState } from "react-dom";
5import Image from "next/image";
6import { fetchFoods, fetchImages } from "@/app/services";
7import { toast } from "react-toastify";
8import SubmitButton from "@/components/SubmitButton";
9import { linkFromGalleryAction } from "@/app/actions";
10import { FoodEntry, ImageEntry } from "@/app/Types";
11
12const STRAPI_URL: string = "http://localhost:1337";
13
14const initialState = {
15  uploadError: null,
16  uploadSuccess: null,
17};
18export default function LinkByGallery() {
19  const [state, formAction] = useFormState(linkFromGalleryAction, initialState);
20  const [foods, setFoods] = useState<FoodEntry[]>([]);
21  const [images, setImages] = useState<ImageEntry[]>([]);
22  const [selectedImageId, setSelectedImageId] = useState<number | string>("");
23
24  const formRef = useRef<HTMLFormElement | null>(null);
25
26  const handleFetchFoods = async () => {
27    const result = await fetchFoods();
28    setFoods(result?.data);
29  };
30
31  const handleFetchImages = async () => {
32    const images = await fetchImages();
33    setImages(images);
34  };
35
36  if (state?.uploadSuccess) {
37    formRef?.current?.reset();
38    toast.success(state?.uploadSuccess);
39    state.uploadSuccess = "";
40  }
41
42  useEffect(() => {
43    handleFetchFoods();
44    handleFetchImages();
45  }, []);
46  return (
47    <div className="w-full">
48      <form ref={formRef} action={formAction} className="flex rounded w-full">
49        <div className="w-full">
50          <div className="flex flex-col pt-10 gap-y-7">
51            <div className="flex flex-col space-y-2">
52              <label htmlFor="name">Food</label>
53              <select
54                name="refId"
55                className="border p-2 text-[#71717a] text-sm w-full"
56                id="food"
57              >
58                {foods.map((food) => {
59                  return <option value={food.documentId}>{food.name}</option>;
60                })}
61              </select>
62              <span className="text-sm text-[#71717a]">
63                Select the food you want to add Image to
64              </span>
65            </div>
66          </div>
67          {images?.length > 0 ? (
68            <div className="grid grid-cols-1 md:grid-cols-3 lg:grid-cols-4 gap-5 w-full pt-10">
69              {images?.map((image) => (
70                <div
71                  className={`${
72                    selectedImageId === image?.id ? "border-2 border-black" : ""
73                  } h-[200px] w-[400]px group relative`}
74                  onClick={() => setSelectedImageId(image?.id)}
75                >
76                  {selectedImageId === image?.id && (
77                    <div className="flex items-center justify-center absolute top-0 left-0 w-full h-full">
78                      <span className="absolute z-50 text-white font-extrabold">
79                        selected
80                      </span>
81                    </div>
82                  )}
83                  <Image
84                    src={`${STRAPI_URL}${image?.url}`}
85                    alt={image.name}
86                    width={400}
87                    height={100}
88                    className={` ${
89                      selectedImageId === image?.id ? " opacity-50 " : " "
90                    } transition-all duration-300 opacity-100 h-full w-full max-w-full rounded-lg group-hover:opacity-50`}
91                  />
92                </div>
93              ))}
94            </div>
95          ) : (
96            <p className="w-full text-orange-300 pt-5">No Images in Gallery.</p>
97          )}
98          <p className="pt-2">
99            {state?.uploadError ? (
100              <span className="text-red-500">{state?.uploadError}</span>
101            ) : null}
102          </p>
103          <input type="hidden" name="imageId" value={selectedImageId} />
104          <div className="pt-5">
105            <SubmitButton title="Link" />
106          </div>
107        </div>
108      </form>
109    </div>
110  );
111}