graphql-mockfiles-express-middleware

GraphQL MockFiles Server

A GraphQL mockserver based on files and a typeDefinition

• GraphQL MockFiles Server
  • Getting started
    • Prepare your mockfiles
    • Setup the express server
• How does it work
• Further work and new features
• Changelog
  • 0.0.2
  • 0.0.1

Getting started

This is a mockserver that can be used as expressjs middleware. It serves mocks based on GraphQL type definitions and a query posted to the server. It can handle aliases.

Be aware that this mock-middleware currently does not support mutations. It could be added in the future

Prepare your mockfiles

To make sure the mockserver can provide you with content to your queries, prepare your directory that contains the responses. The names of each response needs to be ok.json.

Let's take this GraphQL type definition as an example.

type Query {
  posts: [Post]
}
type Post {
  title: String
  content: String
  date: Date
  author: Author
}
type Author {
  name: String
}

So this typedef would result in the following directory structure.

take notion of the author in the second item in the array. The mockfiles-middleware will add author-prop "name": "Albert" to the first item, and leave author-prop "name": "John Doe" in place

mocks/posts/ok.json
[
  {
    "title": "A great post",
    "content": "Lorem ipsum dolor sit amet, [...]",
    "dateCreated": "2019-08-13T15:21:37.978Z"
  },
  {
    "title": "Another post",
    "content": "Suspendisse lectus ligula, pharetra [...]",
    "dateCreated": "2019-08-11T12:21:03.23Z",
    "author": {
      "name": "John Doe"
    }
  }
]

mocks/posts/author/ok.json
{
  "name": "Albert"
}

Setup the express server

Now setup the express server to serve the mockfiles. Take your typeDefs and the path and pass it to the mock-middleware:

const bodyParser = require('body-parser');
const path = require('path');
const app = require('express')();

const {
  createGraphQlMockfilesMiddleware,
} = require('graphql-mockfiles-express-middleware');

function main() {
  const graphqlTypeDefs = `
    type Query {
      hello: String
      me: Me
    }

    type Me {
      posts: [Post]
    }

    type Post {
      title: String
      content: String
      dateCreated: String
    }`;

  app.use(bodyParser.json());
  app.use(
    '/graphql',
    // =====================> Mock Middleware
    createGraphQlMockfilesMiddleware(
      graphqlTypeDefs,
      path.resolve(__dirname, './graphql-mocks')
    )
    // =====================> End Mock Middleware
  );
  app.listen(3000, () =>
    console.log('graphQlMockServer launched at localhost:3000')
  );
}
main();

Now, when executing a query you'd get the results from the mockserver from the files:

{
  posts {
    title
    author {
      name
    }
  }
}

Gives:

{
  "data": {
    "posts": [
      { "title": "A great post", "author": { "name": "Albert" } },
      { "title": "Another post", "author": { "name": "Albert" } }
    ]
  }
}

Now execute a query by posting to the server using your favorite GraphQL client

How does it work

The middleware requires you to give typeDefs and the path to the mock directory. Then each request it basically generates a new middleware based on the response of the paths of your separate queries. Each query creates a set of paths. E.g. the query above creates the following paths (using graphql-query-path)

[
  '/posts/'
  '/posts/title'
  '/posts/author/'
  '/posts/author/name'
]

Technically each of these paths can be represented by an ok.json in the directory structure. Earlier paths are overriding later paths. So if /posts/ok.json already returns a complete object representing what's needed in the query, it'll not get overriden from sub-paths.

This allows for powerful features like setting author's specifically in a Post in /posts/ok.json or generally in /posts/author/ok.json. Have a look at the differences in the posts-mocks in ./graphql-mocks/me/posts/ok.json and the author-mocks in ./graphql-mocks/me/posts/author/ok.json

Further work and new features

• [] make the mockfiles-middleware work for Mutations

Changelog

0.0.2

• Fixed an issue where values that should be in arrays weren't put in array's

0.0.1

• Initial version