# Controllers

# Concept

Controllers are JavaScript files which contain a set of methods called actions reached by the client according to the requested route. It means that every time a client requests the route, the action performs the business logic coded and sends back the response. They represent the C in the MVC pattern. In most cases, the controllers will contain the bulk of a project's business logic.

module.exports = {
  // GET /hello
  index: async ctx => {
    return 'Hello World!';
  },
};

In this example, any time a web browser is pointed to the /hello URL on your app, the page will display the text: Hello World!.

# Where are the controllers defined?

The controllers are defined in each ./api/**/controllers/ folder. Every JavaScript file put in these folders will be loaded as a controller. They are also available through the strapi.controllers and strapi.api.**.controllers global variables.

# Core controllers

When you create a new Content Type you will see a new empty controller has been created. This is because Strapi builds a generic controller for your models by default and allows you to override and extend it in the generated files.

# Extending a Model Controller

Here are the core methods (and their current implementation). You can simply copy and paste this code in your own controller file to customize the methods.

WARNING

In the following example we will assume your controller, service and model are named restaurant

# Utils

First require the utility functions

const { parseMultipartData, sanitizeEntity } = require('strapi-utils');
  • parseMultipartData: This function parses Strapi's formData format.
  • sanitizeEntity: This function removes all private fields from the model and its relations.

# Collection Type

# Single Type

# Custom controllers

You can also create custom controllers to build your own business logic and API endpoints.

# How to create a custom controller

There are two ways to create a controller:

  • Using the CLI strapi generate:controller restaurant.
    Read the CLI documentation for more information.
  • Manually create a JavaScript file in ./api/**/controllers.

# Adding Endpoints

Each controller’s action must be an async function. Every action receives a context (ctx) object as first parameter containing the request context and the response context.

# Example

In this example, we are defining a specific route in ./api/hello/config/routes.json that takes Hello.index as handler.

It means that every time a request GET /hello is sent to the server, Strapi will call the index action in the Hello.js controller. Our index action will return Hello World!. You can also return a JSON object.

Path β€” ./api/hello/config/routes.json.

{
  "routes": [
    {
      "method": "GET",
      "path": "/hello",
      "handler": "Hello.index"
    }
  ]
}

Path β€” ./api/hello/controllers/Hello.js.

module.exports = {
  // GET /hello
  index: async ctx => {
    ctx.send('Hello World!');
  },
};

TIP

A route handler can only access the controllers defined in the ./api/**/controllers folders.