strapi/docs/3.0.0-beta.x/concepts/controllers.md

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 => {
    ctx.send('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/ folders. 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. By convention, controllers' names should be Pascal-cased, so that every word in the file (include the first one) is capitalized User.js, LegalEntity.js.

Core controllers

When you create a new Content type or a new model. You will see a new empty controller has been created. It 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 consider your controller, service and model is 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.

:::: tabs

::: tab find

find

const { sanitizeEntity } = require('strapi-utils');

module.exports = {
  /**
   * Retrieve records.
   *
   * @return {Array}
   */

  async find(ctx) {
    let entities;
    if (ctx.query._q) {
      entities = await strapi.services.restaurant.search(ctx.query);
    } else {
      entities = await strapi.services.restaurant.find(ctx.query);
    }

    return entities.map(entity =>
      sanitizeEntity(entity, { model: strapi.models.restaurant })
    );
  },
};

:::

::: tab findOne

findOne

const { sanitizeEntity } = require('strapi-utils');

module.exports = {
  /**
   * Retrieve a record.
   *
   * @return {Object}
   */

  async findOne(ctx) {
    const entity = await strapi.services.restaurant.findOne(ctx.params);
    return sanitizeEntity(entity, { model: strapi.models.restaurant });
  },
};

:::

::: tab count

count

module.exports = {
  /**
   * Count records.
   *
   * @return {Number}
   */

  count(ctx) {
    if (ctx.query._q) {
      return strapi.services.restaurant.countSearch(ctx.query);
    }
    return strapi.services.restaurant.count(ctx.query);
  },
};

:::

::: tab create

create

const { parseMultipartData, sanitizeEntity } = require('strapi-utils');

module.exports = {
  /**
   * Create a record.
   *
   * @return {Object}
   */

  async create(ctx) {
    let entity;
    if (ctx.is('multipart')) {
      const { data, files } = parseMultipartData(ctx);
      entity = await strapi.services.restaurant.create(data, { files });
    } else {
      entity = await strapi.services.restaurant.create(ctx.request.body);
    }
    return sanitizeEntity(entity, { model: strapi.models.restaurant });
  },
};

:::

::: tab update

update

const { parseMultipartData, sanitizeEntity } = require('strapi-utils');

module.exports = {
  /**
   * Update a record.
   *
   * @return {Object}
   */

  async update(ctx) {
    let entity;
    if (ctx.is('multipart')) {
      const { data, files } = parseMultipartData(ctx);
      entity = await strapi.services.restaurant.update(ctx.params, data, {
        files,
      });
    } else {
      entity = await strapi.services.restaurant.update(
        ctx.params,
        ctx.request.body
      );
    }

    return sanitizeEntity(entity, { model: strapi.models.restaurant });
  },
};

:::

::: tab delete

delete

const { sanitizeEntity } = require('strapi-utils');

module.exports = {
  /**
   * delete a record.
   *
   * @return {Object}
   */

  async delete(ctx) {
    const entity = await strapi.services.restaurant.delete(ctx.params);
    return sanitizeEntity(entity, { model: strapi.models.restaurant });
  },
};

:::

::::

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.

::: tip Every action must be referenced by a route. :::

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 — ./api/hello/config/routes.json.

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

Path — ./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. :::