Mock

Umi provides an out-of-the-box Mock feature, which enables the setup of Mock data in a convenient and simple manner.

:::info{title=💡} What is Mock data: After the front-end and back-end have agreed on the API interface, the front end can use Mock data to simulate the data that the API should return locally. This allows front-end and back-end development to proceed simultaneously, without being blocked by the ongoing development of the backend API. :::

Directory Conventions

Umi conventionally treats all files under the /mock directory as Mock files, like this directory structure:

.
├── mock
    ├── todos.ts
    ├── items.ts
    └── users.ts
└── src
    └── pages
        └── index.tsx

Thus, todos.ts, items.ts, and users.ts in the /mock directory will be processed by Umi as Mock files.

Mock Files

Mock files export an object by default, where each key of the object corresponds to a Mock interface, and the value is the data that should be returned by this interface, like in this Mock file:

// ./mock/users.ts

export default {

  // The return value can be an array
  'GET /api/users': [
    { id: 1, name: 'foo' },
    { id: 2, name: 'bar' }
  ],

  // The return value can also be an object
  'GET /api/users/1': { id: 1, name: 'foo' },

}

This declares two Mock interfaces. Through GET /api/users, you can get an array with two user data. Through GET /api/users/1, you can get simulated data for a user.

Request Methods

When the HTTP request method is GET, you can omit the method part and only need the path, like:

// ./mock/users.ts

export default {

  '/api/users': [
    { id: 1, name: 'foo' },
    { id: 2, name: 'bar' }
  ],

  '/api/users/1': { id: 1, name: 'foo' },

}

You can also use different request methods, such as POST, PUT, DELETE:

// ./mock/users.ts

export default {

  'POST /api/users': { result: 'true' },

  'PUT /api/users/1': { id: 1, name: 'new-foo' },

}

Custom Functions

In addition to directly declaring static return values, you can also use functions to declare how to compute the return values, like:

export default {

  'POST /api/users/create': (req, res) => {
    // Add CORS headers
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.end('ok');
  }

}

For the APIs of req and res, refer to the Express@4 official documentation for further understanding.

defineMock

Furthermore, you can use the defineMock type helper function to provide code hints for writing mock objects, like:

import { defineMock } from "umi";

export default defineMock({
  "/api/users": [
    { id: 1, name: "foo" },
    { id: 2, name: "bar" },
  ],
  "/api/users/1": { id: 1, name: "foo" },
  "GET /api/users/2": (req, res) => {
    res.status(200).json({ id: 2, name: "bar" });
  },
});

defineMock simply provides type hints; the input and output are completely identical.

Disabling Mock

Mock functionality is enabled by default in Umi. If it's not needed, it can be disabled from the config file:

// .umirc.ts

export default {
  mock: false,
};

Or by using an environmental variable:

MOCK=none umi dev

Integrating Mock.js

In Mock, we often use Mock.js to help us conveniently generate random simulated data. If you are using Umi's Mock functionality, it's recommended to pair it with this library to enhance the realism of the simulated data:

import mockjs from 'mockjs';

export default {
  // Using third-party libraries like mockjs
  'GET /api/tags': mockjs.mock({
    'list|100': [{ name: '@city', 'value|1-100': 50, 'type|0-2': 1 }],
  }),
};

Other Configurations

For a complete list of other configuration options for Mock functionality, please see the configuration section of the documentation.