Java Resolvers

Package name	Weekly Downloads	Version	License	Updated
`@graphql-codegen/java-resolvers` (opens in a new tab)				Jul 22nd, 2023

Installation

pnpm add -D @graphql-codegen/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 (opens in a new tab) 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:

package.json

{
  "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:

codegen.yml

schema: src/main/resources/schema.graphqls
generates:
  src/main/java/com/my-name/my-app/generated/File.java:
    - RELEVANT_PLUGIN # Replace with your plugin name

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

.gitignore

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.

Config 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

`strictScalars`

type: boolean default: false

Makes scalars strict.

If scalars are found in the schema that are not defined in scalars an error will be thrown during codegen.

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         strictScalars: true,
       },
     },
   },
 };
 export default config;

`defaultScalarType`

type: string default: any

Allows you to override the type that unknown scalars will have.

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         defaultScalarType: 'unknown'
       },
     },
   },
 };
 export default config;

`scalars`

type: ScalarsMap

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

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         scalars: {
           DateTime: 'Date',
           JSON: '{ [key: string]: any }',
         }
       },
     },
   },
 };
 export default config;

`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 preserve 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 (opens in a new tab)

Usage Examples

Override All Names

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         namingConvention: 'change-case-all#lowerCase',
       },
     },
   },
 };
 export default config;

Upper-case enum values

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         namingConvention: {
           typeNames: 'change-case-all#pascalCase',
           enumValues: 'change-case-all#upperCase',
         }
       },
     },
   },
 };
 export default config;

Keep names as is

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
        namingConvention: 'keep',
       },
     },
   },
 };
 export default config;

Remove Underscores

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         namingConvention: {
           typeNames: 'change-case-all#pascalCase',
           transformUnderscore: true
         }
       },
     },
   },
 };
 export default config;

`typesPrefix`

type: string default: (empty)

Prefixes all the generated types.

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         typesPrefix: 'I',
       },
     },
   },
 };
 export default config;

`typesSuffix`

type: string default: (empty)

Suffixes all the generated types.

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         typesSuffix: 'I',
       },
     },
   },
 };
 export default config;

`skipTypename`

type: boolean default: false

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

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         skipTypename: true
       },
     },
   },
 };
 export default config;

`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

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         nonOptionalTypename: true
       },
     },
   },
 };
 export default config;

`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

Usage Examples

codegen.ts

 import type { CodegenConfig } from '@graphql-codegen/cli';
 
 const config: CodegenConfig = {
   // ...
   generates: {
     'path/to/file': {
       // plugins...
       config: {
         useTypeImports: true
       },
     },
   },
 };
 export default config;

`dedupeFragments`

type: boolean default: false

Removes fragment duplicates for reducing data transfer. It is done by removing sub-fragments imports from fragment definition Instead - all of them are imported to the Operation node.

`inlineFragmentTypes`

type: string default: inline

Whether fragment types should be inlined into other operations. "inline" is the default behavior and will perform deep inlining fragment types within operation type definitions. "combine" is the previous behavior that uses fragment type references without inlining the types (and might cause issues with deeply nested fragment that uses list types).

`emitLegacyCommonJSImports`

type: boolean default: true

Emit legacy common js imports. Default it will be true this way it ensure that generated code works with non-compliant bundlers (opens in a new tab).

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