Persisted document custom hash function

.changeset/spicy-starfishes-press.md

@@ -0,0 +1,30 @@
+---
+"@graphql-codegen/client-preset": patch
+"website": patch
+---
+
+Added configuration to allow for custom hash functions for persisted documents in the client preset
+
+### Example
+```ts filename="codegen.ts" {10-12}
+import { type CodegenConfig } from '@graphql-codegen/cli'
+
+const config: CodegenConfig = {
+  schema: 'schema.graphql',
+  documents: ['src/**/*.tsx'],
+  generates: {
+    './src/gql/': {
+      preset: 'client',
+      presetConfig: {
+        persistedDocuments: {
+          hashAlgorithm: operation => {
+            const shasum = crypto.createHash('sha512')
+            shasum.update(operation)
+            return shasum.digest('hex')
+          }
+        }
+      }
+    }
+  }
+}
+```

packages/presets/client/src/index.ts

@@ -84,14 +84,16 @@ export type ClientPresetConfig = {
          */
         hashPropertyName?: string;
         /**
-         * @description Algorithm used to generate the hash, could be useful if your server expects something specific (e.g., Apollo Server expects `sha256`).
+         * @description Algorithm or function used to generate the hash, could be useful if your server expects something specific (e.g., Apollo Server expects `sha256`).
+         *
+         * A custom hash function can be provided to generate the hash if the preset algorithms don't fit your use case. The function receives the operation and should return the hash string.
          *
          * The algorithm parameter is typed with known algorithms and as a string rather than a union because it solely depends on Crypto's algorithms supported
          * by the version of OpenSSL on the platform.
          *
          * @default `sha1`
          */
-        hashAlgorithm?: 'sha1' | 'sha256' | (string & {});
+        hashAlgorithm?: 'sha1' | 'sha256' | (string & {}) | ((operation: string) => string);
       };
 };
 

packages/presets/client/src/persisted-documents.ts

@@ -1,11 +1,17 @@
-import * as crypto from 'crypto';
 import { printExecutableGraphQLDocument } from '@graphql-tools/documents';
-import { type DocumentNode, Kind, visit } from 'graphql';
+import * as crypto from 'crypto';
+import { Kind, visit, type DocumentNode } from 'graphql';
 
 /**
  * This function generates a hash from a document node.
  */
-export function generateDocumentHash(operation: string, algorithm: 'sha1' | 'sha256' | (string & {})): string {
+export function generateDocumentHash(
+  operation: string,
+  algorithm: 'sha1' | 'sha256' | (string & {}) | ((operation: string) => string)
+): string {
+  if (typeof algorithm === 'function') {
+    return algorithm(operation);
+  }
   const shasum = crypto.createHash(algorithm);
   shasum.update(operation);
   return shasum.digest('hex');