BackendSrv: support binary responseType like $http did (#29004)

packages/grafana-runtime/src/services/backendSrv.ts

@@ -62,6 +62,15 @@ export type BackendSrvRequest = {
   params?: Record<string, any>;
 
   /**
+   * Define how the response object should be parsed.  See:
+   *
+   * https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Sending_and_Receiving_Binary_Data
+   *
+   * By default values are json parsed from text
+   */
+  responseType?: 'json' | 'text' | 'arraybuffer' | 'blob';
+
+  /**
    * The credentials read-only property of the Request interface indicates whether the user agent should send cookies from the other domain in the case of cross-origin requests.
    */
   credentials?: RequestCredentials;

public/app/core/services/backend_srv.ts

@@ -11,7 +11,7 @@ import { DashboardSearchHit } from 'app/features/search/types';
 import { FolderDTO } from 'app/types';
 import { coreModule } from 'app/core/core_module';
 import { ContextSrv, contextSrv } from './context_srv';
-import { parseInitFromOptions, parseUrlFromOptions } from '../utils/fetch';
+import { parseInitFromOptions, parseResponseBody, parseUrlFromOptions } from '../utils/fetch';
 import { isDataQuery, isLocalUrl } from '../utils/query';
 import { FetchQueue } from './FetchQueue';
 import { ResponseQueue } from './ResponseQueue';
@@ -175,15 +175,8 @@ export class BackendSrv implements BackendService {
     return this.dependencies.fromFetch(url, init).pipe(
       mergeMap(async response => {
         const { status, statusText, ok, headers, url, type, redirected } = response;
-        const textData = await response.text(); // this could be just a string, prometheus requests for instance
-        let data: T;
-
-        try {
-          data = JSON.parse(textData); // majority of the requests this will be something that can be parsed
-        } catch {
-          data = textData as any;
-        }
 
+        const data = await parseResponseBody<T>(response, options.responseType);
         const fetchResponse: FetchResponse<T> = {
           status,
           statusText,

public/app/core/utils/fetch.test.ts

@@ -5,6 +5,7 @@ import {
   parseCredentials,
   parseHeaders,
   parseInitFromOptions,
+  parseResponseBody,
   parseUrlFromOptions,
 } from './fetch';
 
@@ -127,3 +128,48 @@ describe('parseCredentials', () => {
     }
   );
 });
+
+describe('parseResponseBody', () => {
+  const rsp = ({} as unknown) as Response;
+  it('parses json', async () => {
+    const value = { hello: 'world' };
+    const body = await parseResponseBody(
+      {
+        ...rsp,
+        json: jest.fn().mockImplementationOnce(() => value),
+      },
+      'json'
+    );
+    expect(body).toEqual(value);
+  });
+
+  it('parses text', async () => {
+    const value = 'RAW TEXT';
+    const body = await parseResponseBody(
+      {
+        ...rsp,
+        text: jest.fn().mockImplementationOnce(() => value),
+      },
+      'text'
+    );
+    expect(body).toEqual(value);
+  });
+
+  it('undefined text', async () => {
+    const value = 'RAW TEXT';
+    const body = await parseResponseBody({
+      ...rsp,
+      text: jest.fn().mockImplementationOnce(() => value),
+    });
+    expect(body).toEqual(value);
+  });
+
+  it('undefined as parsed json', async () => {
+    const value = { hello: 'world' };
+    const body = await parseResponseBody({
+      ...rsp,
+      text: jest.fn().mockImplementationOnce(() => JSON.stringify(value)),
+    });
+    expect(body).toEqual(value);
+  });
+});

public/app/core/utils/fetch.ts

@@ -91,6 +91,33 @@ export const parseBody = (options: BackendSrvRequest, isAppJson: boolean) => {
   return isAppJson ? JSON.stringify(options.data) : new URLSearchParams(options.data);
 };
 
+export async function parseResponseBody<T>(
+  response: Response,
+  responseType?: 'json' | 'text' | 'arraybuffer' | 'blob'
+): Promise<T> {
+  if (responseType) {
+    switch (responseType) {
+      case 'arraybuffer':
+        return response.arrayBuffer() as any;
+
+      case 'blob':
+        return response.blob() as any;
+
+      case 'json':
+        return response.json();
+
+      case 'text':
+        return response.text() as any;
+    }
+  }
+
+  const textData = await response.text(); // this could be just a string, prometheus requests for instance
+  try {
+    return JSON.parse(textData); // majority of the requests this will be something that can be parsed
+  } catch {}
+  return textData as any;
+}
+
 export function serializeParams(data: Record<string, any>): string {
   return Object.keys(data)
     .map(key => {