feat: add casing support for generated filenames

This allows users to control the naming convention of generated resolver files,
supporting common filename formats, while preserving original default functionality.

Details:

- Add change-case-all dependency to typescript-resolver-files package
- Add fileOutputCasing config option with 'pascal-case' (default) and other casing support
- Update preset config validation to include fileOutputCasing option
- Add transformResolverFileName utility to convert resolver names to appropriate filename casing
- Integrate filename transformation throughout the resolver generation pipeline
- Add unit test coverage for filename transformation functionality
- Add e2e test suite
- Update documentation in README.md

Author: jruhland

packages/typescript-resolver-files-e2e/project.json

@@ -165,6 +165,13 @@
             "rimraf -g \"{projectRoot}/src/test-complex-synth-generic-wrapper/**/*.generated.*\""
           ],
           "parallel": false
+        },
+        "test-resolver-filename-case": {
+          "commands": [
+            "rimraf -g \"{projectRoot}/src/test-resolver-filename-case/**/resolvers/\"",
+            "rimraf -g \"{projectRoot}/src/test-resolver-filename-case/**/*.generated.*\""
+          ],
+          "parallel": false
         }
       }
     },
@@ -191,7 +198,8 @@
           "nx graphql-codegen typescript-resolver-files-e2e -c test-resolvers-auto-wireup --verbose",
           "nx graphql-codegen typescript-resolver-files-e2e -c test-federation --verbose",
           "nx graphql-codegen typescript-resolver-files-e2e -c test-deep-modules --verbose",
-          "nx graphql-codegen typescript-resolver-files-e2e -c test-complex-synth-generic-wrapper --verbose"
+          "nx graphql-codegen typescript-resolver-files-e2e -c test-complex-synth-generic-wrapper --verbose",
+          "nx graphql-codegen typescript-resolver-files-e2e -c test-resolver-filename-case --verbose"
         ],
         "parallel": false
       },
@@ -269,6 +277,9 @@
         },
         "test-complex-synth-generic-wrapper": {
           "configFile": "{projectRoot}/src/test-complex-synth-generic-wrapper/codegen.ts"
+        },
+        "test-resolver-filename-case": {
+          "configFile": "{projectRoot}/src/test-resolver-filename-case/codegen.ts"
         }
       },
       "dependsOn": ["prepare-e2e-modules"]

packages/typescript-resolver-files-e2e/src/test-resolver-filename-case/codegen.ts

@@ -0,0 +1,24 @@
+import type { CodegenConfig } from '@graphql-codegen/cli';
+import { defineConfig } from '@eddeee888/gcg-typescript-resolver-files';
+
+const config: CodegenConfig = {
+  hooks: {
+    afterAllFileWrite: ['prettier --write'],
+  },
+  generates: {
+    'packages/typescript-resolver-files-e2e/src/test-filename-case-kebab/schema':
+      defineConfig(
+        {
+          fileOutputCasing: 'kebab-case',
+        },
+        {
+          schema: [
+            'packages/typescript-resolver-files-e2e/src/test-filename-case-kebab/**/*.graphqls',
+            'packages/typescript-resolver-files-e2e/src/test-filename-case-kebab/**/*.graphqls.ts',
+          ],
+        }
+      ),
+  },
+};
+
+export default config;

packages/typescript-resolver-files-e2e/src/test-resolver-filename-case/schema/base.graphqls

@@ -0,0 +1,15 @@
+
+scalar DateTime
+scalar SomeRandomScalar
+
+type Query {
+  # Simple: "randomQuery" -> "random-query.ts"
+  randomQuery: RandomScalar!
+  # Strange: "api-random-query.ts"
+  APIRandomQuery: APIRandomQuery!
+}
+
+type Mutation {
+  # Strange: "random-api-mutation.ts"
+  RandomAPIMutation: RandomAPIMutationResult!
+}

packages/typescript-resolver-files-e2e/src/test-resolver-filename-case/schema/user.graphqls.ts

@@ -0,0 +1,18 @@
+import gql from 'graphql-tag';
+
+export const userTypeDefs = gql`
+  extend type Query {
+    userProfile(id: ID!): UserProfile!
+    user(id: ID!): UserPayload!
+  }
+
+  # Single-word type: User -> user.ts
+  type User {
+    id: ID!
+  }
+
+  # Multi-word type: UserProfile -> user-profile.ts
+  type UserProfile {
+    id: ID!
+  }
+`;

packages/typescript-resolver-files/README.md

@@ -261,6 +261,44 @@ Hint: To see why certain files are skipped, run codegen command with `DEBUG` tur
 DEBUG="@eddeee888/gcg-typescript-resolver-files" yarn graphql-codegen
 ```
 
+### fileOutputCasing
+
+`string` (Default: `pascal-case`)
+
+Controls the naming convention used for generated resolver filenames. By default, resolver files are generated using PascalCase (e.g., `UserProfile.ts`), but you can customize this to match your project's file naming conventions.
+
+Supported options:
+- `pascal-case` (default): `UserProfile.ts`, `APIKey.ts`
+- `kebab-case` or `param-case`: `user-profile.ts`, `api-key.ts`
+- `camel-case`: `userProfile.ts`, `apiKey.ts`
+- `snake-case`: `user_profile.ts`, `api_key.ts`
+- `constant-case`: `USER_PROFILE.ts`, `API_KEY.ts`
+- `dot-case`: `user.profile.ts`, `api.key.ts`
+- `header-case`: `User-Profile.ts`, `Api-Key.ts`
+- `lower-case`: `userprofile.ts`, `apikey.ts`
+- `upper-case`: `USERPROFILE.ts`, `APIKEY.ts`
+- `no-case`: `user profile.ts`, `api key.ts`
+- `path-case`: `user/profile.ts`, `api/key.ts`
+- `sentence-case`: `User profile.ts`, `Api key.ts`
+- `title-case`: `UserProfile.ts`, `APIKey.ts`
+- `capital-case`: `User Profile.ts`, `Api Key.ts`
+
+#### Example
+
+```ts
+// codegen.ts
+defineConfig({
+  fileOutputCasing: 'kebab-case',
+});
+```
+
+This configuration will generate resolver files like:
+- `src/schema/user/resolvers/user-profile.ts` (instead of `UserProfile.ts`)
+- `src/schema/user/resolvers/Query/user-by-id.ts` (instead of `userById.ts`)
+- `src/schema/api/resolvers/api-key.ts` (instead of `APIKey.ts`)
+
+Note: This option only affects the filename casing. The exported resolver variable names and TypeScript interfaces remain unchanged to maintain valid JavaScript identifiers.
+
 ### typeDefsFileMode
 
 `merged` or `mergedWhitelisted` or `modules` (Default: `merged`)

packages/typescript-resolver-files/package.json

@@ -35,6 +35,7 @@
     "@graphql-codegen/typescript-resolvers": "^4.4.2",
     "@graphql-tools/merge": "^9.0.4",
     "@graphql-tools/utils": "^10.0.0",
+    "change-case-all": "^1.0.0",
     "micromatch": "^4.0.0",
     "ts-morph": "^22.0.0",
     "tslib": "^2.3.0"

packages/typescript-resolver-files/src/parseGraphQLSchema/parseGraphQLSchema.ts

@@ -24,6 +24,7 @@ import {
   isNativeNamedType,
   isRootObjectType,
   relativeModulePath,
+  transformResolverFileName,
   type RootObjectType,
 } from '../utils';
 import { parseLocationForOutputDir } from './parseLocationForOutputDir';
@@ -42,6 +43,7 @@ interface ParseGraphQLSchemaParams {
   resolverRelativeTargetDir: string;
   whitelistedModules: ParsedPresetConfig['whitelistedModules'];
   blacklistedModules: ParsedPresetConfig['blacklistedModules'];
+  fileOutputCasing: ParsedPresetConfig['fileOutputCasing'];
 }
 
 export interface ResolverDetails {
@@ -113,6 +115,7 @@ export const parseGraphQLSchema = async ({
   resolverRelativeTargetDir,
   whitelistedModules,
   blacklistedModules,
+  fileOutputCasing,
 }: ParseGraphQLSchemaParams): Promise<ParsedGraphQLSchemaMeta> => {
   const scalarsModuleResolverMap = scalarsModule
     ? await getScalarResolverMapFromModule(scalarsModule)
@@ -144,6 +147,7 @@ export const parseGraphQLSchema = async ({
               nestedDirs: [schemaType],
               location: fieldNode.astNode?.loc,
               resolverName: fieldName,
+              fileOutputCasing,
             });
             if (!resolverDetails) {
               return;
@@ -187,6 +191,7 @@ export const parseGraphQLSchema = async ({
           namedType,
           schemaType,
           result: res,
+          fileOutputCasing,
         });
         return res;
       }
@@ -220,6 +225,7 @@ export const parseGraphQLSchema = async ({
         nestedDirs: [],
         location: namedType.astNode?.loc,
         resolverName: namedType.name,
+        fileOutputCasing,
       });
 
       if (resolverDetails) {
@@ -358,6 +364,7 @@ const handleObjectType = ({
   namedType,
   schemaType,
   result,
+  fileOutputCasing,
 }: {
   mode: ParseGraphQLSchemaParams['mode'];
   sourceMap: ParseGraphQLSchemaParams['sourceMap'];
@@ -369,6 +376,7 @@ const handleObjectType = ({
   namedType: GraphQLObjectType;
   schemaType: string;
   result: ParsedGraphQLSchemaMeta;
+  fileOutputCasing: ParsedPresetConfig['fileOutputCasing'];
 }): void => {
   // parse for details
   const fieldsByGraphQLModule = Object.entries(namedType.getFields()).reduce<
@@ -420,6 +428,7 @@ const handleObjectType = ({
         nestedDirs: [],
         location: firstFieldLocation,
         resolverName: namedType.name,
+        fileOutputCasing,
       });
 
       if (!resolverDetails) {
@@ -457,6 +466,7 @@ const createResolverDetails = ({
   nestedDirs,
   location,
   resolverName,
+  fileOutputCasing,
 }: {
   belongsToRootObject: RootObjectType | null;
   mode: ParseGraphQLSchemaParams['mode'];
@@ -470,6 +480,7 @@ const createResolverDetails = ({
   nestedDirs: string[];
   location: Location | undefined;
   resolverName: string;
+  fileOutputCasing: ParsedPresetConfig['fileOutputCasing'];
 }): ResolverDetails | undefined => {
   const parsedDetails = parseLocationForOutputDir({
     nestedDirs,
@@ -494,16 +505,17 @@ const createResolverDetails = ({
     belongsToRootObject
   );
 
+  const transformedFileName = transformResolverFileName(resolverName, fileOutputCasing);
   const resolverFilePath = path.posix.join(
     resolversOutputDir,
-    `${resolverName}.ts`
+    `${transformedFileName}.ts`
   );
 
   return {
     schemaType,
     moduleName,
     resolverFile: {
-      name: resolverName,
+      name: transformedFileName,
       path: resolverFilePath,
       isOnFilesystem: fs.existsSync(resolverFilePath),
     },

packages/typescript-resolver-files/src/preset.ts

@@ -71,6 +71,7 @@ export const preset: Types.OutputPreset<RawPresetConfig> = {
       tsMorphProjectOptions,
       fixObjectTypeResolvers,
       emitLegacyCommonJSImports,
+      fileOutputCasing,
     } = validatePresetConfig(rawPresetConfig);
 
     const resolverTypesPath = path.posix.join(
@@ -121,6 +122,7 @@ export const preset: Types.OutputPreset<RawPresetConfig> = {
           resolverRelativeTargetDir,
           whitelistedModules,
           blacklistedModules,
+          fileOutputCasing,
         }),
       createProfilerRunName('parseGraphQLSchema')
     );

packages/typescript-resolver-files/src/utils/index.ts

@@ -9,3 +9,4 @@ export * from './printImportLine';
 export * from './normalizeRelativePath';
 export * from './relativeModulePath';
 export * from './isMatchResolverNamePattern';
+export * from './transformResolverFileName';