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Services

Page summary:

Services store reusable functions to keep controllers concise and follow DRY principles. This documentation explains generating or extending services with createCoreService and organizing them for APIs or plugins.

Services are a set of reusable functions. They are particularly useful to respect the "don’t repeat yourself" (DRY) programming concept and to simplify controllers logic.

Simplified Strapi backend diagram with services highlighted
The diagram represents a simplified version of how a request travels through the Strapi back end, with services highlighted. The backend customization introduction page includes a complete, interactive diagram.

Implementation​

Services can be generated or added manually. Strapi provides a createCoreService factory function that automatically generates core services and allows building custom ones or extend or replace the generated services.

Adding a new service​

A new service can be implemented:

To manually create a service, export a factory function that returns the service implementation (i.e. an object with methods). This factory function receives the strapi instance:

./src/api/restaurant/services/restaurant.js

const { createCoreService } = require('@strapi/strapi').factories;

module.exports = createCoreService('api::restaurant.restaurant', ({ strapi }) =>  ({
  // Method 1: Creating an entirely new custom service
  async exampleService(...args) {
    let response = { okay: true }

    if (response.okay === false) {
      return { response, error: true }
    }

    return response
  },

  // Method 2: Wrapping a core service (leaves core logic in place)
  async find(...args) {  
    // Calling the default core controller
    const { results, pagination } = await super.find(...args);

    // some custom logic
    results.forEach(result => {
      result.counter = 1;
    });

    return { results, pagination };
  },

  // Method 3: Replacing a core service
  async findOne(documentId, params = {}) {
    return strapi.documents('api::restaurant.restaurant').findOne({
        documentId, 
        // Use super to keep core fetch parameter formatting
        ...super.getFetchParams(params),
     });
  }
}));
Document Service API

To get started creating your own services, see Strapi's built-in functions in the Document Service API documentation.

Example of a custom email service (using Nodemailer)

The goal of a service is to store reusable functions. A sendNewsletter service could be useful to send emails from different functions in our codebase that have a specific purpose:

./src/api/restaurant/services/restaurant.js


const { createCoreService } = require('@strapi/strapi').factories;
const nodemailer = require('nodemailer'); // Requires nodemailer to be installed (npm install nodemailer)

// Create reusable transporter object using SMTP transport.
const transporter = nodemailer.createTransport({
  service: 'Gmail',
  auth: {
    user: 'user@gmail.com',
    pass: 'password',
  },
});

module.exports = createCoreService('api::restaurant.restaurant', ({ strapi }) => ({
  sendNewsletter(from, to, subject, text) {
    // Setup e-mail data.
    const options = {
      from,
      to,
      subject,
      text,
    };

    // Return a promise of the function that sends the email.
    return transporter.sendMail(options);
  },
}));

The service is now available through the strapi.service('api::restaurant.restaurant').sendNewsletter(...args) global variable. It can be used in another part of the codebase, like in the following controller:

./src/api/restaurant/controllers/restaurant.js

module.exports = createCoreController('api::restaurant.restaurant', ({ strapi }) =>  ({
  // GET /hello
  async signup(ctx) {
    const { userData } = ctx.body;

    // Store the new user in database.
    const user = await strapi.service('plugin::users-permissions.user').add(userData);

    // Send an email to validate his subscriptions.
    strapi.service('api::restaurant.restaurant').sendNewsletter('welcome@mysite.com', user.email, 'Welcome', '...');

    // Send response to the server.
    ctx.send({
      ok: true,
    });
  },
}));
Note

When a new content-type is created, Strapi builds a generic service with placeholder code, ready to be customized.

Extending core services​

Core services are created for each content-type and could be used by controllers to execute reusable logic through a Strapi project. Core services can be customized to implement your own logic. The following code examples should help you get started.

Tip

A core service can be replaced entirely by creating a custom service and naming it the same as the core service (e.g. find, findOne, create, update, or delete).

Collection type examples
async find(params) {
  // some logic here
  const { results, pagination } = await super.find(params);
  // some more logic

  return { results, pagination };
}
Single type examples
async find(params) {
  // some logic here
  const document = await super.find(params);
  // some more logic

  return document;
}

Usage​

Once a service is created, it's accessible from controllers or from other services:

// access an API service
strapi.service('api::apiName.serviceName').FunctionName();
// access a plugin service
strapi.service('plugin::pluginName.serviceName').FunctionName();

In the syntax examples above, serviceName is the name of the service file for API services or the name used to export the service file to services/index.js for plugin services.

Tip

To list all the available services, run yarn strapi services:list.

Core service methods​

Services generated with createCoreService inherit methods that wrap the Document Service API. The available methods depend on the content-type:

Collection types​

MethodDescription
find(params)Wrapper for findMany; returns a paginated list of documents.
findOne(documentId, params)Wrapper for findOne; returns a single document by its documentId.
create(params)Wrapper for create; creates a new document.
update(documentId, params)Wrapper for update; updates an existing document.
delete(documentId, params)Wrapper for delete; removes a document.
count(params)Wrapper for count; returns the number of matching documents.
publish(documentId, params)Wrapper for publish; publishes a draft document.
unpublish(documentId, params)Wrapper for unpublish; unpublishes a document.
discardDraft(documentId, params)Wrapper for discardDraft; deletes the draft copy.

Single types​

MethodDescription
find(params)Returns the single document (uses findFirst internally).
createOrUpdate({ data, ...params })Creates the document if it doesn't exist or updates it (uses update).
delete(params)Deletes the document (uses delete).
count(params)Counts documents matching the filters (uses count).
publish(params)Publishes a draft document (uses publish).
unpublish(params)Unpublishes the document (uses unpublish).
discardDraft(params)Deletes the draft copy (uses discardDraft).

Parameters and default behavior​

Core service methods accept the same parameters as their underlying Document Service API calls, such as fields, filters, sort, pagination, populate, locale, and status. When no status is provided, Strapi automatically sets status: 'published' so only published content is returned. To query draft documents, explicitly pass status: 'draft' or another value supported by the Document Service.

The createCoreService factory also exposes a getFetchParams(params) helper that converts a controller's query object into the parameter format expected by these methods. This helper can be reused when overriding core methods to forward sanitized parameters to strapi.documents().

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