Backend Methods

Backend methods run on the backend and are used to improve performance, execute server-only code (e.g., sending emails), or perform operations not accessible through the API.

Static Backend Methods

Static backend methods represent the most straightforward type, transmitting their parameters to the backend and delivering their outcome to the frontend.

1. Define the Backend Method:

import { BackendMethod, repo } from 'remult'
import { Task } from './Task'

export class TasksController {
  /**
   * Sets the completion status of all tasks.
   * @param {boolean} completed - The completion status to set for all tasks.
   */
  @BackendMethod({ allowed: true })
  static async setAll(completed: boolean) {
    const taskRepo = repo(Task)

    for (const task of await taskRepo.find()) {
      await taskRepo.save({ ...task, completed })
    }
  }
}

Each controller can house one or more backend methods, each serving distinct purposes tailored to your application's needs. In the provided example, the TasksController class contains a single backend method named setAll, responsible for setting the completion status of all tasks.

The method name, such as setAll, serves as the URL for the corresponding REST endpoint on the backend server. It's worth noting that you can configure a prefix for these endpoints using the apiPrefix option, providing flexibility in structuring your backend API routes.

The allowed: true parameter signifies that the backend method can be invoked by anyone. Alternatively, you can customize the authorization settings for finer control over who can access the method.

For instance, setting allow: Allow.authenticated restricts access to authenticated users only, ensuring that only logged-in users can utilize the method.

Similarly, specifying allow: 'admin' limits access to users with administrative privileges, granting access exclusively to administrators.

These options offer granular control over authorization, allowing you to tailor access permissions based on your application's specific requirements and security considerations.

2. Register the Controller:

// Register TasksController in the controllers array of the remultExpress options
export const api = remultExpress({
  entities: [Task],
  controllers: [TasksController],
})

3. Call from the Frontend:

await TasksController.setAll(true)

This example demonstrates how to define and use a static backend method, setAll, within the TasksController class. When called from the frontend, this method sets the completion status of all tasks to the specified value (true in this case). The method leverages Remult's BackendMethod decorator to handle the communication between the frontend and backend seamlessly.