feat: add marker interface support for union types (#39)

BREAKING CHANGE: generate marker interfaces for union types by default

Author: danadajian

.releaserc.yaml

@@ -7,7 +7,7 @@ plugins:
         - type: breaking
           release: major
         - type: docs
-          release: patch
+          release: false
         - type: refactor
           release: patch
         - scope: no-release

bun.lockb

@@ -5,5 +5,5 @@ sidebar_position: 3
 # Configuration
 
 ```ts reference title="Config Schema"
-https://github.com/ExpediaGroup/graphql-kotlin-codegen/blob/main/src/config.ts#L17-L100000
+https://github.com/ExpediaGroup/graphql-kotlin-codegen/blob/main/src/config.ts#L1-L100000
 ```

docs/docs/configuration.md

@@ -13,6 +13,7 @@ export default [
       },
     },
     rules: {
+      "no-console": "error",
       "@typescript-eslint/no-non-null-assertion": "error",
       "@typescript-eslint/no-unsafe-argument": "error",
       "@typescript-eslint/no-unsafe-call": "error",

eslint.config.js

@@ -28,7 +28,7 @@
     "@graphql-codegen/cli": "5.0.2",
     "@total-typescript/ts-reset": "0.5.1",
     "bun-types": "1.1.4",
-    "eslint": "9.1.0",
+    "eslint": "9.1.1",
     "husky": "9.0.11",
     "prettier": "3.2.5",
     "tsup": "8.0.2",
@@ -39,7 +39,7 @@
     "build": "tsup src/plugin.ts --clean --dts --external graphql",
     "format": "prettier --write .",
     "format-check": "prettier --check .",
-    "integration": "bun run build && graphql-codegen && ./gradlew compileTestKotlin",
+    "integration": "bun run build && graphql-codegen && ./gradlew build",
     "lint": "eslint .",
     "prepack": "bun run build",
     "prepare": "husky",

package.json

@@ -15,6 +15,7 @@ import {
   array,
   boolean,
   enum_,
+  literal,
   object,
   optional,
   string,
@@ -44,11 +45,11 @@ export const configSchema = object({
   dependentTypesInScope: optional(array(string())),
   /**
    * Denotes Kotlin classes representing union types to be treated as interfaces rather than annotation classes.
-   * This should be used for types outside `dependentTypesInScope` that are not generated by the plugin.
+   * @description This should be used for types outside `dependentTypesInScope` that are not generated by the plugin. Only use when unionGeneration is set to `ANNOTATION_CLASS`.
    */
   externalUnionsAsInterfaces: optional(array(string())),
   /**
-   * Additional imports to add to the generated file.
+   * Additional imports to add to the generated file. GraphQL Kotlin annotations are always imported.
    * @example ["com.example.additional.import.*"]
    */
   extraImports: optional(array(string())),
@@ -129,4 +130,12 @@ export const configSchema = object({
       }),
     ),
   ),
+  /**
+   * Denotes the generation strategy for union types. Defaults to `MARKER_INTERFACE`.
+   * @description The `MARKER_INTERFACE` option is highly recommended, since it is more type-safe than using annotation classes.
+   * @link https://opensource.expediagroup.com/graphql-kotlin/docs/schema-generator/writing-schemas/unions/
+   */
+  unionGeneration: optional(
+    union([literal("ANNOTATION_CLASS"), literal("MARKER_INTERFACE")]),
+  ),
 });

src/config.ts

@@ -15,11 +15,11 @@ import { EnumTypeDefinitionNode, EnumValueDefinitionNode } from "graphql";
 import { indentMultiline } from "@graphql-codegen/visitor-plugin-common";
 import { buildAnnotations } from "../helpers/build-annotations";
 import { shouldIncludeTypeDefinition } from "../helpers/should-include-type-definition";
-import { CodegenConfig } from "../plugin";
+import { CodegenConfigWithDefaults } from "../helpers/build-config-with-defaults";
 
 export function buildEnumTypeDefinition(
   node: EnumTypeDefinitionNode,
-  config: CodegenConfig,
+  config: CodegenConfigWithDefaults,
 ) {
   if (!shouldIncludeTypeDefinition(node, config)) {
     return "";
@@ -46,11 +46,11 @@ ${indentMultiline(enumValues.join(",\n") + ";", 2)}
 
 function buildEnumValueDefinition(
   node: EnumValueDefinitionNode,
-  config: CodegenConfig,
+  config: CodegenConfigWithDefaults,
 ) {
   const annotations = buildAnnotations({
     config,
     definitionNode: node,
   });
-  return `${annotations}${config.convert(node)}`;
+  return `${annotations}${config.convert?.(node)}`;
 }

src/definitions/enum.ts

@@ -16,12 +16,12 @@ import { shouldIncludeTypeDefinition } from "../helpers/should-include-type-defi
 import { buildTypeMetadata } from "../helpers/build-type-metadata";
 import { buildAnnotations } from "../helpers/build-annotations";
 import { indent } from "@graphql-codegen/visitor-plugin-common";
-import { CodegenConfig } from "../plugin";
+import { CodegenConfigWithDefaults } from "../helpers/build-config-with-defaults";
 
 export function buildInputObjectDefinition(
   node: InputObjectTypeDefinitionNode,
   schema: GraphQLSchema,
-  config: CodegenConfig,
+  config: CodegenConfigWithDefaults,
 ) {
   if (!shouldIncludeTypeDefinition(node, config)) {
     return "";
@@ -47,7 +47,6 @@ export function buildInputObjectDefinition(
 
   const annotations = buildAnnotations({
     config,
-    inputDescription: node.description?.value,
     definitionNode: node,
   });
 

src/definitions/input.ts

@@ -17,12 +17,12 @@ import { indent } from "@graphql-codegen/visitor-plugin-common";
 import { buildTypeMetadata } from "../helpers/build-type-metadata";
 import { shouldIncludeTypeDefinition } from "../helpers/should-include-type-definition";
 import { buildFieldDefinition } from "../helpers/build-field-definition";
-import { CodegenConfig } from "../plugin";
+import { CodegenConfigWithDefaults } from "../helpers/build-config-with-defaults";
 
 export function buildInterfaceDefinition(
   node: InterfaceTypeDefinitionNode,
   schema: GraphQLSchema,
-  config: CodegenConfig,
+  config: CodegenConfigWithDefaults,
 ) {
   if (!shouldIncludeTypeDefinition(node, config)) {
     return "";

src/definitions/interface.ts

@@ -16,16 +16,19 @@ import { buildAnnotations } from "../helpers/build-annotations";
 import { indent } from "@graphql-codegen/visitor-plugin-common";
 import { buildTypeMetadata } from "../helpers/build-type-metadata";
 import { shouldIncludeTypeDefinition } from "../helpers/should-include-type-definition";
-import { getDependentInterfaceNames } from "../helpers/dependent-type-utils";
+import {
+  getDependentInterfaceNames,
+  getDependentUnionsForType,
+} from "../helpers/dependent-type-utils";
 import { isResolverType } from "../helpers/is-resolver-type";
 import { buildFieldDefinition } from "../helpers/build-field-definition";
 import { isExternalField } from "../helpers/is-external-field";
-import { CodegenConfig } from "../plugin";
+import { CodegenConfigWithDefaults } from "../helpers/build-config-with-defaults";
 
 export function buildObjectTypeDefinition(
   node: ObjectTypeDefinitionNode,
   schema: GraphQLSchema,
-  config: CodegenConfig,
+  config: CodegenConfigWithDefaults,
 ) {
   if (!shouldIncludeTypeDefinition(node, config)) {
     return "";
@@ -36,33 +39,38 @@ export function buildObjectTypeDefinition(
     definitionNode: node,
   });
   const name = node.name.value;
-  const interfacesToInherit = getDependentInterfaceNames(node);
+  const dependentInterfaces = getDependentInterfaceNames(node);
+  const dependentUnions = getDependentUnionsForType(schema, node);
+  const interfacesToInherit =
+    config.unionGeneration === "MARKER_INTERFACE"
+      ? dependentInterfaces.concat(dependentUnions)
+      : dependentInterfaces;
   const interfaceInheritance = `${interfacesToInherit.length ? ` : ${interfacesToInherit.join(", ")}` : ""}`;
 
   if (isResolverType(node, config)) {
     return `${annotations}@GraphQLIgnore\ninterface ${name}${interfaceInheritance} {
-${getClassMembers({ node, schema, config })}
+${getDataClassMembers({ node, schema, config })}
 }
 
 ${annotations}@GraphQLIgnore\ninterface ${name}CompletableFuture {
-${getClassMembers({ node, schema, config, completableFuture: true })}
+${getDataClassMembers({ node, schema, config, completableFuture: true })}
 }`;
   }
 
   return `${annotations}data class ${name}(
-${getClassMembers({ node, schema, config })}
+${getDataClassMembers({ node, schema, config })}
 )${interfaceInheritance}`;
 }
 
-function getClassMembers({
+function getDataClassMembers({
   node,
   schema,
   config,
   completableFuture,
 }: {
   node: ObjectTypeDefinitionNode;
   schema: GraphQLSchema;
-  config: CodegenConfig;
+  config: CodegenConfigWithDefaults;
   completableFuture?: boolean;
 }) {
   const resolverType = isResolverType(node, config);