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Loaders and Data Fetching in routes.json

This document explains how to configure and use loaders, actions, and handle server-side and client-side code separation in your routes using the routes.json file.

Server-Side Loaders​

Server-side loaders are used to fetch data on the server before rendering a component. They are configured using the hasLoader field in routes.json. By default, server-side code must be located in files ending with .server.js for security and performance reasons.

Syntax​

{
  "/path": {
    "hasLoader": true,
    "componentPath": "@adminide-stack/user-auth0/lib/components/callback.server.js"
  }
}

Implementation​

When hasLoader is set to true, you need to implement a loader function in your route file:

export const loader = async ({ params, context }) => {
  // Fetch data here
  return { data };
};

Handling Component with server code by using hasServerCode​

Remix recommends separating server-side logic into .server.js files for security and performance reasons. When the hasServerCode flag is set to true, it means that server-side code like loaders, actions, and headers will be located in a .server.js file, while client-side logic remains in the main component file.

To ensure that routes understands there is a .server.js file in addition to componentPath, make sure to set hasServerCode to true.

Example Configuration When hasServerCode is true​

{
  "/login": {
    "hasLoader": true,
    "hasServerCode": true,
    "componentPath": "@adminide-stack/user-auth0-browser-ant/lib/components/Login/index.js"
  }
}

Generated Wrapper When hasServerCode is true​

import OriginalComponent from '@adminide-stack/user-auth0-browser-ant/lib/components/Login/index.js';
import { loader as loaderFunc } from '@adminide-stack/user-auth0-browser-ant/lib/components/Login/index.server.js';

Example Configuration When hasServerCode is false​

{
  "/login": {
    "hasLoader": true,
    "hasServerCode": false,
    "componentPath": "@adminide-stack/user-auth0-browser-ant/lib/components/Login/index.js"
  }
}

Generated Wrapper When hasServerCode is false​

import OriginalComponent, { loader as loaderFunc } from '@adminide-stack/user-auth0-browser-ant/lib/components/Login/index.js';

By separating the server-side code into .server.js files, we ensure that sensitive server-side logic is not included in the client bundle, as recommended by Remix.

Client-Side Loaders​

Client-side loaders are used to fetch data on the client after the initial render. They are configured using the hasClientLoader field in routes.json.

Syntax​

{
  "/path": {
    "hasClientLoader": true
  }
}

Implementation​

When hasClientLoader is set to true, you need to implement a client loader function:

export const clientLoader = async ({ params }) => {
  // Fetch data here
  return { data };
};

Actions for Form Submissions and Mutations​

Actions are used for handling form submissions and mutations. They are configured using the hasAction field in routes.json.

Syntax​

{
  "/path": {
    "hasAction": true
  }
}

Implementation​

When hasAction is set to true, you need to implement an action function:

export const action = async ({ request }) => {
  // Handle form submission or mutation here
  return { result };
};

Integrating Loaders with Authentication and Authorization​

Loaders can be integrated with authentication and authorization by checking the user's permissions before fetching data:

export const loader = async ({ params, context }) => {
  const { user } = context;
  if (!user) {
    throw new Error('Unauthorized');
  }
  if (!user.hasPermission('required.permission')) {
    throw new Error('Forbidden');
  }
  // Fetch data here
  return { data };
};

Why Separating Server-Side Code Matters​

Separating server-side code into .server.js files provides the following benefits:

  1. Security: Sensitive logic is not included in the client bundle.
  2. Performance: Smaller client bundles and faster loading times.
  3. Clarity: Clear distinction between client and server code, improving maintainability.

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