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Java Resolvers

The java-resolvers plugin creates Java interfaces for the resolvers signature.

It works with graphql-java library and it uses it's DataFetcher API.

You can use this plugin to generate interfaces and later implement them, this way you can always tell if one of the fields is missing a resolvers:

import com.my.app.generated.Resolvers;
import com.my.app.models.User;
import graphql.schema.DataFetcher;
export class QueryResolvers implements Resolvers.Query {
public DataFetcher<String> id() {
return environment -> environment.<User>getSource().getId();
}
}

Prepare your environment#

To use the GraphQL Code Generator with Java, start by adding the com.moowork.node Gradle plugin to your build.gradle:

plugins {
id "com.moowork.node" version "1.3.1"
}

Then, add the following in order to make sure you are running the code-generator on each build:

build.dependsOn yarn

Then, create a package.json file in your project root, with the following content:

{
"name": "java-app",
"scripts": {
"postinstall": "graphql-codegen"
},
"dependencies": {
"graphql": "14.5.8",
"@graphql-codegen/cli": "1.7.0",
"@graphql-codegen/RELEVANT_PLUGIN": "1.7.0"
}
}

Make sure to use the latest version of codegen and the plugins, and replace RELEVANT_PLUGIN with your plugin name.

Then, create codegen.yml file in your root directory, pointing to your schema, and add the plugins you need. For example:

schema: src/main/resources/schema.graphqls
generates:
src/main/java/com/my-name/my-app/generated/File.java:
- RELEVANT_PLUGIN

Replace RELEVANT_PLUGIN with your plugin name.

Also, make sure you add the following to your .gitignore file:

yarn.lock
node_modules

Now, run gradle yarn to install the dependencies for the first time.

Next time, the codegen will run automatically each time you run your Gradle build script.

Installation

java-resolvers plugin version
Using yarn
yarn add -D @graphql-codegen/java-resolvers

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/java/my-org/my-app/Resolvers.java:
plugins:
- java-resolvers
config:
package: custom.package.name

mappers

type: object

Allow you to replace specific GraphQL types with your custom model classes. This is useful when you want to make sure your resolvers returns the correct class. The default value is the values set by defaultMapper configuration. You can use a direct path to the package, or use package#class syntax to have it imported.

Usage Examples

generates:
src/main/java/my-org/my-app/Resolvers.java:
plugins:
- java-resolvers
config:
mappers:
User: com.app.models#UserObject

defaultMapper

type: string default: Object

Sets the default mapper value in case it's not specified by mappers. You can use a direct path to the package, or use package#class syntax to have it imported. The default mapper is Java's Object.

Usage Examples

generates:
src/main/java/my-org/my-app/Resolvers.java:
plugins:
- java-resolvers
config:
defaultMapper: my.app.models.BaseEntity

className

type: string default: Resolvers

Allow you to customize the parent class name.

Usage Examples

generates:
src/main/java/my-org/my-app/Resolvers.java:
plugins:
- java-resolvers
config:
className: MyResolvers

listType

type: string default: Iterable

Allow you to customize the list type.

Usage Examples

generates:
src/main/java/my-org/my-app/Resolvers.java:
plugins:
- java-resolvers
config:
listType: Map

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