feat(load-files): ability to provide a custom extractExports (#2700)

Author: ardatan

.changeset/lucky-bats-relax.md

@@ -0,0 +1,5 @@
+---
+'@graphql-tools/load-files': minor
+---
+
+feat(load-files): ability to provide a custom extractExports

packages/load-files/src/index.ts

@@ -7,7 +7,30 @@ const { readFile, stat } = fsPromises;
 
 const DEFAULT_IGNORED_EXTENSIONS = ['spec', 'test', 'd', 'map'];
 const DEFAULT_EXTENSIONS = ['gql', 'graphql', 'graphqls', 'ts', 'js'];
-const DEFAULT_EXPORT_NAMES = ['typeDefs', 'schema'];
+const DEFAULT_EXPORT_NAMES = ['schema', 'typeDef', 'typeDefs', 'resolver', 'resolvers'];
+const DEFAULT_EXTRACT_EXPORTS_FACTORY = (exportNames: string[]) => (fileExport: any): any | null => {
+  if (!fileExport) {
+    return null;
+  }
+
+  if (fileExport.default) {
+    for (const exportName of exportNames) {
+      if (fileExport.default[exportName]) {
+        return fileExport.default[exportName];
+      }
+    }
+
+    return fileExport.default;
+  }
+
+  for (const exportName of exportNames) {
+    if (fileExport[exportName]) {
+      return fileExport[exportName];
+    }
+  }
+
+  return fileExport;
+};
 
 function asArray<T>(obj: T | T[]): T[] {
   if (obj instanceof Array) {
@@ -56,30 +79,6 @@ function buildGlob(
   return `${basePath}${recursive ? '/**' : ''}/${ignored}+(${ext})`;
 }
 
-function extractExports(fileExport: any, exportNames: string[]): any | null {
-  if (!fileExport) {
-    return null;
-  }
-
-  if (fileExport.default) {
-    for (const exportName of exportNames) {
-      if (fileExport.default[exportName]) {
-        return fileExport.default[exportName];
-      }
-    }
-
-    return fileExport.default;
-  }
-
-  for (const exportName of exportNames) {
-    if (fileExport[exportName]) {
-      return fileExport[exportName];
-    }
-  }
-
-  return fileExport;
-}
-
 /**
  * Additional options for loading files
  */
@@ -100,6 +99,8 @@ export interface LoadFilesOptions {
   recursive?: boolean;
   // Set to `true` to ignore files named `index.js` and `index.ts`
   ignoreIndex?: boolean;
+  // Custom export extractor function
+  extractExports?: (fileExport: any) => any;
 }
 
 const LoadFilesDefaultOptions: LoadFilesOptions = {
@@ -134,6 +135,9 @@ export function loadFilesSync<T = any>(
     options.globOptions
   );
 
+  const extractExports = execOptions.extractExports || DEFAULT_EXTRACT_EXPORTS_FACTORY(execOptions.exportNames);
+  const requireMethod = execOptions.requireMethod || require;
+
   return relevantPaths
     .map(path => {
       if (!checkExtension(path, options)) {
@@ -147,33 +151,8 @@ export function loadFilesSync<T = any>(
       const extension = extname(path);
 
       if (extension === formatExtension('js') || extension === formatExtension('ts') || execOptions.useRequire) {
-        const fileExports = (execOptions.requireMethod ? execOptions.requireMethod : require)(path);
-        const extractedExport = extractExports(fileExports, execOptions.exportNames);
-
-        if (extractedExport.typeDefs && extractedExport.resolvers) {
-          return extractedExport;
-        }
-
-        if (extractedExport.schema) {
-          return extractedExport.schema;
-        }
-
-        if (extractedExport.typeDef) {
-          return extractedExport.typeDef;
-        }
-
-        if (extractedExport.typeDefs) {
-          return extractedExport.typeDefs;
-        }
-
-        if (extractedExport.resolver) {
-          return extractedExport.resolver;
-        }
-
-        if (extractedExport.resolvers) {
-          return extractedExport.resolvers;
-        }
-
+        const fileExports = requireMethod(path);
+        const extractedExport = extractExports(fileExports);
         return extractedExport;
       } else {
         return readFileSync(path, { encoding: 'utf-8' });
@@ -232,7 +211,9 @@ export async function loadFiles(
     options.globOptions
   );
 
-  const require$ = (path: string) => import(path).catch(async () => require(path));
+  const extractExports = execOptions.extractExports || DEFAULT_EXTRACT_EXPORTS_FACTORY(execOptions.exportNames);
+  const defaultRequireMethod = (path: string) => import(path).catch(async () => require(path));
+  const requireMethod = execOptions.requireMethod || defaultRequireMethod;
 
   return Promise.all(
     relevantPaths
@@ -241,8 +222,8 @@ export async function loadFiles(
         const extension = extname(path);
 
         if (extension === formatExtension('js') || extension === formatExtension('ts') || execOptions.useRequire) {
-          const fileExports = await (execOptions.requireMethod ? execOptions.requireMethod : require$)(path);
-          const extractedExport = extractExports(fileExports, execOptions.exportNames);
+          const fileExports = await requireMethod(path);
+          const extractedExport = extractExports(fileExports);
 
           if (extractedExport.resolver) {
             return extractedExport.resolver;

packages/load-files/tests/file-scanner.spec.ts

@@ -1,5 +1,8 @@
 import { loadFilesSync, loadFiles, LoadFilesOptions } from '@graphql-tools/load-files';
 import { print } from 'graphql';
+import { join } from 'path';
+
+const syncAndAsync = Object.entries({ 'SYNC': loadFilesSync, 'ASYNC': loadFiles });
 
 function testSchemaDir({ path, expected, note, extensions, ignoreIndex }: TestDirOptions) {
   let options: LoadFilesOptions;
@@ -15,29 +18,22 @@ function testSchemaDir({ path, expected, note, extensions, ignoreIndex }: TestDi
     };
   });
 
-  it(`SYNC: should return the correct schema results for path: ${path} (${note})`, () => {
-    const result = loadFilesSync(path, options);
-
-    expect(result.length).toBe(expected.length);
-    expect(result.map(res => {
-      if (res.kind === 'Document') {
-        res = print(res);
-      }
-      return stripWhitespaces(res);
-    })).toEqual(expected.map(stripWhitespaces));
-  });
+  syncAndAsync.forEach(([type, loadFiles]) => {
+    describe(type, () => {
+      it(`should return the correct schema results for path: ${path} (${note})`, async () => {
+        const result = await loadFiles(path, options);
 
-  it(`ASYNC: should return the correct schema results for path: ${path} (${note})`, async () => {
-    const result = await loadFiles(path, options);
+        expect(result.length).toBe(expected.length);
+        expect(result.map(res => {
+          if (res.kind === 'Document') {
+            res = print(res);
+          }
+          return stripWhitespaces(res);
+        })).toEqual(expected.map(stripWhitespaces));
+      });
+    });
+  })
 
-    expect(result.length).toBe(expected.length);
-    expect(result.map(res => {
-      if (res.kind === 'Document') {
-        res = print(res);
-      }
-      return stripWhitespaces(res);
-    })).toEqual(expected.map(stripWhitespaces));
-  });
 }
 
 function testResolversDir({ path, expected, note, extensions, compareValue, ignoreIndex, ignoredExtensions }: TestDirOptions) {
@@ -58,24 +54,18 @@ function testResolversDir({ path, expected, note, extensions, compareValue, igno
     };
   });
 
-  it(`SYNC: should return the correct resolvers results for path: ${path} (${note})`, () => {
-    const result = loadFilesSync(path, options);
-
-    expect(result.length).toBe(expected.length);
-
-    if (compareValue) {
-      expect(result).toEqual(expected);
-    }
-  });
-
-  it(`ASYNC: should return the correct resolvers results for path: ${path} (${note})`, async () => {
-    const result = await loadFiles(path, options);
+  syncAndAsync.forEach(([type, loadFiles]) => {
+    describe(type, () => {
+      it(`should return the correct resolvers results for path: ${path} (${note})`, async () => {
+        const result = await loadFiles(path, options);
 
-    expect(result.length).toBe(expected.length);
+        expect(result.length).toBe(expected.length);
 
-    if (compareValue) {
-      expect(result).toEqual(expected);
-    }
+        if (compareValue) {
+          expect(result).toEqual(expected);
+        }
+      });
+    })
   });
 }
 
@@ -228,6 +218,24 @@ describe('file scanner', function() {
       note: 'extensions and ignored extensions works with a trailing dot',
     });
   });
+  syncAndAsync.forEach(([type, loadFiles]) => {
+    it(`${type}: should process custom extractExports properly`, async () => {
+      const customQueryTypeName = 'root_query';
+      const customExtractExports = (fileExport: any) => {
+        fileExport = fileExport.default || fileExport;
+        // Incoming exported value is function
+        return fileExport(customQueryTypeName);
+      };
+      const loadedFiles = await loadFiles(join(__dirname, './test-assets/custom-extractor/factory-func.js'), {
+        extractExports: customExtractExports
+      });
+      expect(loadedFiles).toHaveLength(1);
+      expect(customQueryTypeName in loadedFiles[0]).toBeTruthy();
+      expect('foo' in loadedFiles[0][customQueryTypeName]).toBeTruthy();
+      expect(typeof loadedFiles[0][customQueryTypeName]['foo']).toBe('function');
+      expect(loadedFiles[0][customQueryTypeName]['foo']()).toBe('FOO');
+    });
+  })
 });
 
 interface TestDirOptions {

packages/load-files/tests/test-assets/custom-extractor/factory-func.js

@@ -0,0 +1,5 @@
+module.exports = QueryTypeName => ({
+  [QueryTypeName]: {
+    foo: () => 'FOO'
+  }
+});

website/docs/schema-merging.md

@@ -414,3 +414,31 @@ Or by **type**...
 |   |   |   +-- ...
 |   |   +-- index.ts <<< Merges all `*.resolvers.*` files
 ```
+
+**Custom extraction from exports**
+
+By default, `loadFiles` checks export names `typeDefs`, `resolvers` and `schema`. But you can change the way it extracts the content from the exported values.
+
+Let's say you have a factory function inside your resolvers like below;
+
+```js
+module.exports = customQueryTypeName = ({
+  [customQueryTypeName]: {
+    foo: () => 'FOO',
+  }
+})
+```
+
+And you can define custom `extractExports` like below;
+```js
+const { loadFilesSync } = require('@graphql-tools/load-files');
+
+const resolvers = loadFilesSync(join(__dirname, './resolvers/**/*.js'), {
+  extractExports: fileExport => {
+    if (typeof fileExport === 'function') {
+      return fileExport('query_root');
+    }
+    return fileExport;
+  }
+})
+```