Add GraphQL ID conversion helpers

app/assets/javascripts/graphql_shared/utils.js

@@ -14,3 +14,41 @@ export const MutationOperationMode = {
   Remove: 'REMOVE',
   Replace: 'REPLACE',
 };
+
+/**
+ * Possible GraphQL entity types.
+ */
+export const TYPE_GROUP = 'Group';
+
+/**
+ * Ids generated by GraphQL endpoints are usually in the format
+ * gid://gitlab/Groups/123. This method takes a type and an id
+ * and interpolates the 2 values into the expected GraphQL ID format.
+ *
+ * @param {String} type The entity type
+ * @param {String|Number} id The id value
+ * @returns {String}
+ */
+export const convertToGraphQLId = (type, id) => {
+  if (typeof type !== 'string') {
+    throw new TypeError(`type must be a string; got ${typeof type}`);
+  }
+
+  if (!['number', 'string'].includes(typeof id)) {
+    throw new TypeError(`id must be a number or string; got ${typeof id}`);
+  }
+
+  return `gid://gitlab/${type}/${id}`;
+};
+
+/**
+ * Ids generated by GraphQL endpoints are usually in the format
+ * gid://gitlab/Groups/123. This method takes a type and an
+ * array of ids and tranforms the array values into the expected
+ * GraphQL ID format.
+ *
+ * @param {String} type The entity type
+ * @param {Array} ids An array of id values
+ * @returns {Array}
+ */
+export const convertToGraphQLIds = (type, ids) => ids.map(id => convertToGraphQLId(type, id));

spec/frontend/graphql_shared/utils_spec.js

-import { getIdFromGraphQLId } from '~/graphql_shared/utils';
+import {
+  getIdFromGraphQLId,
+  convertToGraphQLId,
+  convertToGraphQLIds,
+} from '~/graphql_shared/utils';
+
+const mockType = 'Group';
+const mockId = 12;
+const mockGid = `gid://gitlab/Group/12`;
 
 describe('getIdFromGraphQLId', () => {
   [
@@ -44,3 +52,32 @@ describe('getIdFromGraphQLId', () => {
     });
   });
 });
+
+describe('convertToGraphQLId', () => {
+  it('combines $type and $id into $result', () => {
+    expect(convertToGraphQLId(mockType, mockId)).toBe(mockGid);
+  });
+
+  it.each`
+    type        | id        | message
+    ${mockType} | ${null}   | ${'id must be a number or string; got object'}
+    ${null}     | ${mockId} | ${'type must be a string; got object'}
+  `('throws TypeError with "$message" if a param is missing', ({ type, id, message }) => {
+    expect(() => convertToGraphQLId(type, id)).toThrow(new TypeError(message));
+  });
+});
+
+describe('convertToGraphQLIds', () => {
+  it('combines $type and $id into $result', () => {
+    expect(convertToGraphQLIds(mockType, [mockId])).toStrictEqual([mockGid]);
+  });
+
+  it.each`
+    type        | ids               | message
+    ${mockType} | ${null}           | ${"Cannot read property 'map' of null"}
+    ${mockType} | ${[mockId, null]} | ${'id must be a number or string; got object'}
+    ${null}     | ${[mockId]}       | ${'type must be a string; got object'}
+  `('throws TypeError with "$message" if a param is missing', ({ type, ids, message }) => {
+    expect(() => convertToGraphQLIds(type, ids)).toThrow(new TypeError(message));
+  });
+});