gatsby-source-mock

This plugin allows you to mock GraphQL data in Gatsby sites using Faker.js or custom callback functions. This is especially useful for mocking datasets that are still under development and can be hooked in later.

This plugin is based on the official gatsby-source-faker plugin.

Install

npm install --save gatsby-source-mock

or

yarn add gatsby-source-mock

How to use

Define the schema in gatsby-config.js. See a full list of options here.

module.exports = {
  plugins: [
    {
      resolve: `gatsby-source-mock`,
      options: {
        schema: {
          name: `{{name.firstName}} {{name.lastName}}`,
          company: `{{company.companyName}}`,
          balance: (faker) => faker.finance.amount() / 2,
          features: {
            accountType: (faker) =>
              faker.random.arrayElement(['Free', 'Premium']),
            creditCard: {
              isValid: (faker) => faker.datatype.boolean(),
              number: `{{finance.creditCardNumber}}`,
            },
            account: {
              iban: `{{finance.iban}}`,
              bic: `{{finance.bic}}`,
            },
          },
        },
        count: 10,
        type: `BankAccount`,
        seed: 123456,
        locale: `de`,
      },
    },
  ],
};

Faker.fake()

All strings will be parsed with Faker.fake(), so you may use a mustache string format to use Faker.js methods:

{
  options: {
    schema: {
      fullName: '{{name.firstName}} {{name.lastName}}',
      ...
    },
  }
}

Callback

You may pass a callback function which will receive an instance of Faker. This can be useful for more complex situations:

{
  options: {
    schema: {
      emoji: (faker) => {
        return faker.random.arrayElement(
          ['🤖', '✌️', '🎮', '✊', '🙃']
        );
      },
      ...
    },
  }
}

The callback function will also receive the index of the current run as a second argument:

{
  options: {
    schema: {
      counter: (faker, index) => {
        return `Number ${index + 1}`;
      },
      ...
    },
  }
}

Defining data types

You can explicitely define data types by providing schema keys as <name>:<type>:

{
  options: {
    schema: {
      'title:String!': '{{lorem.sentence}}',
      'publishedAt:Date!': faker => faker.date.past(),
      'likes:Number': faker => faker.datatype.number(),
      subline: '{{lorem.sentence}}',
    },
  }
}

This would result in a schema definition like this:

id: ID!
title: String!
publishedAt(
  difference: String
  formatString: String
  fromNow: Boolean
  locale: String
): Date
likes: Number
subline: String

Passing a dataset

You may define a dataset explicitely by passing an array to schema. You can still use Faker.js interpolation and callback functions:

module.exports = {
  plugins: [
    {
      resolve: `gatsby-source-mock`,
      options: {
        schema: [
          {
            name: `Fred {{name.lastName}}`,
            about: (faker) => faker.lorem.paragraphs(3),
          },
          {
            name: `Hermine {{name.lastName}}`,
            about: (faker) => faker.lorem.paragraph(),
          },
          {
            name: `{{name.firstName}} Bowie`,
            about: (faker) => faker.lorem.paragraphs(2),
          },
        ],
        type: `User`,
      },
    },
  ],
};

You can also define a dataset and the count parameter to generate multiple nodes of the given dataset.

This example will create three nodes named Harry and two nodes named Hermine each with a random last name:

module.exports = {
  plugins: [
    {
      resolve: `gatsby-source-mock`,
      options: {
        schema: [
          {
            name: `Harry {{name.lastName}}`,
          },
          {
            name: `Hermine {{name.lastName}}`,
          },
        ],
        type: `Hogwarts`,
        count: 5,
      },
    },
  ],
};

Options

Option Description
schema  The object describing the schema
count  The number of fake items being generated, defaults to 10
type  Name of the graphql query node
seed  You may specify a randomness seed to get consistent results
locale  You may specify a locale for fakes, defaults to en

Query mock data

The GraphQL query will match the specified schema, for the example above it could look like this:

query {
  allBankAccount(limit: 2) {
    edges {
      node {
        id
        balance
        id
        name
        company
        features {
          account {
            bic
            iban
          }
          creditCard {
            number
            isValid
          }
        }
      }
    }
  }
}

The result for this example may look something like this:

{
  "data": {
    "allBankAccount": {
      "edges": [
        {
          "node": {
            "balance": 448.62,
            "id": "155df202-6533-5eea-a2b7-fbb4e796bdab",
            "name": "Filip Laurén",
            "company": "Thyssen, Grasse and Restorff",
            "features": {
              "account": {
                "bic": "SGHEAFZ1",
                "iban": "BG79YWJV02007108V69521"
              },
              "creditCard": {
                "number": "6384-3821-1503-3495",
                "isValid": false
              }
            }
          }
        },
        {
          "node": {
            "balance": 112.395,
            "id": "3c523dc7-4771-557b-aa0b-f0b5124dd78b",
            "name": "Rike Weller",
            "company": "Breitenstein OHG",
            "features": {
              "account": {
                "bic": "CVCUAZT1",
                "iban": "MK64263157663695906"
              },
              "creditCard": {
                "number": "5434-1536-6521-4284",
                "isValid": false
              }
            }
          }
        }
      ]
    }
  },
  "extensions": {}
}