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Kotlin

The kotlin plugin generates Kotlin classes for Enums and Input types.

You can use this plugin to generate Java enums based on your GraphQL schema, and it also generates a type-safe Kotlin transformer for GraphQL input types.

Prepare your environment#

To get started with this plugins and preset, make sure you have the following installed:

  • NodeJS (10 or later)
  • NPM or Yarn

Run the following in your Android project:

yarn init --yes
yarn add @graphql-codegen/cli graphql @graphql-codegen/kotlin

Then, create codegen.yml with the following configuration:

schema: POINT_TO_YOUR_SCHEMA
documents: POINT_TO_YOUR_GRAPHQL_OPERATIONS
generates:
./app/src/Types.kt:
plugins:
- kotlin

Also, make sure to add node_modules to your .gitignore file.

Installation

kotlin plugin version
Using yarn
yarn add -D @graphql-codegen/kotlin

API Reference

package

type: string

Customize the Java package name. The default package name will be generated according to the output file path.

Usage Examples

generates:
src/main/kotlin/my-org/my-app/Resolvers.kt:
plugins:
- kotlin
config:
package: custom.package.name

enumValues

type: EnumValuesMap

Overrides the default value of enum values declared in your GraphQL schema.

listType

type: string default: Iterable

Allow you to customize the list type

Usage Examples

generates:
src/main/kotlin/my-org/my-app/Types.kt:
plugins:
- kotlin
config:
listType: Map

withTypes

type: boolean default: false

Allow you to enable generation for the types

Usage Examples

generates:
src/main/kotlin/my-org/my-app/Types.kt:
plugins:
- kotlin
config:
withTypes: true

scalars

type: ScalarsMap

Extends or overrides the built-in scalars and custom GraphQL scalars to a custom type.

namingConvention

type: NamingConvention default: change-case-all#pascalCase

Allow you to override the naming convention of the output. You can either override all namings, or specify an object with specific custom naming convention per output. The format of the converter must be a valid module#method. Allowed values for specific output are: typeNames, enumValues. You can also use "keep" to keep all GraphQL names as-is. Additionally you can set transformUnderscore to true if you want to override the default behavior, which is to preserves underscores.

Available case functions in change-case-all are camelCase, capitalCase, constantCase, dotCase, headerCase, noCase, paramCase, pascalCase, pathCase, sentenceCase, snakeCase, lowerCase, localeLowerCase, lowerCaseFirst, spongeCase, titleCase, upperCase, localeUpperCase and upperCaseFirst See more

typesPrefix

type: string default: ``

Prefixes all the generated types.

Usage Examples

config:
typesPrefix: I

typesSuffix

type: string default: ``

Suffixes all the generated types.

Usage Examples

config:
typesSuffix: I

skipTypename

type: boolean default: false

Does not add __typename to the generated types, unless it was specified in the selection set.

Usage Examples

config:
skipTypename: true

nonOptionalTypename

type: boolean default: false

Automatically adds __typename field to the generated types, even when they are not specified in the selection set, and makes it non-optional

Usage Examples

config:
nonOptionalTypename: true

useTypeImports

type: boolean default: false

Will use import type {} rather than import {} when importing only types. This gives compatibility with TypeScript's "importsNotUsedAsValues": "error" option