Skip to content

Generating fake data

You can generate fake data for fields in your mock.

Examples include, but are not limited to:

  • Names
  • Email addresses
  • Addresses

Setup

Option 1: Using the fake-data plugin

To use it, install the fake-data plugin:

imposter plugin install -d fake-data

Option 2: Using the 'all' distribution

Alternatively, you can use the all distribution, which includes the fake-data plugin.

This is the docker-all engine type if you're using the CLI or the imposter-all.jar file if you're using the JAR file approach.

Generating fake data

Fake data expressions

You can use template expressions in responses to insert fake data. The expressions start with fake. followed by a type of fake data to generate.

For example, to return a random first name, use the following expression:

${fake.Name.firstName}

For an email address:

${fake.Internet.emailAddress}

Some common examples:

Fake data Expression
First name fake.Name.firstName
Last name fake.Name.lastName
Email address fake.Internet.emailAddress
Username fake.Name.username
Street address fake.Address.streetAddress
City fake.Address.city
Country fake.Address.country
Phone number fake.PhoneNumber.phoneNumber

Note Valid values are those supported by the Datafaker library.

Try it out

See the example directory for a working example.

curl http://localhost:8080/users/1

{
  "id": 1,
  "firstName": "Linda",
  "lastName": "Smith",
  "email": "linda@example.com"
}

Fake data in OpenAPI specs

Note This section applies to the OpenAPI plugin.

When using the fake-data plugin with the OpenAPI plugin, common property names in the OpenAPI specification, such as firstName, email etc., are replaced with fake data. This happens when no matching example is found in the specification.

Try it out

See the example directory for a working example.

For example:

curl http://localhost:8080/users/1

{
  "id": 1,
  "firstName": "Linda",
  "lastName": "Smith",
  "email": "linda@example.com",
  "address": {
    "street": "123 Main St",
    "city": "New York",
    "postcode": "10001"
  },
  "favouriteColour": "red"
}

Customizing the fake data

You can customize the fake data by adding a x-fake-data property to the field in the OpenAPI file.

This is done for the favouriteColour field in the example:

favouriteColour:
  type: string
  x-fake-data: Color.name

Note Valid values are those supported by the Datafaker library.