Fix: Set correct branch when it's not specified in the config

jest.config.js

@@ -5,6 +5,9 @@ module.exports = {
     'netlify-cms-lib-util': '<rootDir>/packages/netlify-cms-lib-util/src/index.ts',
     'netlify-cms-ui-default': '<rootDir>/packages/netlify-cms-ui-default/src/index.js',
     'netlify-cms-backend-github': '<rootDir>/packages/netlify-cms-backend-github/src/index.ts',
+    'netlify-cms-backend-gitlab': '<rootDir>/packages/netlify-cms-backend-gitlab/src/index.ts',
+    'netlify-cms-backend-bitbucket':
+      '<rootDir>/packages/netlify-cms-backend-bitbucket/src/index.ts',
     'netlify-cms-lib-widgets': '<rootDir>/packages/netlify-cms-lib-widgets/src/index.ts',
     'netlify-cms-widget-object': '<rootDir>/packages/netlify-cms-widget-object/src/index.js',
     '\\.(css|less)$': '<rootDir>/__mocks__/styleMock.js',

packages/netlify-cms-backend-bitbucket/src/implementation.ts

@@ -25,6 +25,7 @@ import {
   allEntriesByFolder,
   AccessTokenError,
   branchFromContentKey,
+  getDefaultBranchName,
 } from 'netlify-cms-lib-util';
 import { NetlifyAuthenticator } from 'netlify-cms-lib-auth';
 
@@ -72,6 +73,7 @@ export default class BitbucketBackend implements Implementation {
     initialWorkflowStatus: string;
   };
   repo: string;
+  isBranchConfigured: boolean;
   branch: string;
   apiRoot: string;
   baseUrl: string;
@@ -111,6 +113,7 @@ export default class BitbucketBackend implements Implementation {
 
     this.repo = config.backend.repo || '';
     this.branch = config.backend.branch || 'master';
+    this.isBranchConfigured = config.backend.branch ? true : false;
     this.apiRoot = config.backend.api_root || 'https://api.bitbucket.org/2.0';
     this.baseUrl = config.base_url || '';
     this.siteId = config.site_id || '';
@@ -216,7 +219,16 @@ export default class BitbucketBackend implements Implementation {
     if (!isCollab) {
       throw new Error('Your BitBucket user account does not have access to this repo.');
     }
-
+    if (!this.isBranchConfigured) {
+      const defaultBranchName = await getDefaultBranchName({
+        backend: 'bitbucket',
+        repo: this.repo,
+        token: this.token,
+      });
+      if (defaultBranchName) {
+        this.branch = defaultBranchName;
+      }
+    }
     const user = await this.api.user();
 
     // Authorized user

packages/netlify-cms-backend-github/src/implementation.tsx

@@ -20,6 +20,7 @@ import {
   contentKeyFromBranch,
   unsentRequest,
   branchFromContentKey,
+  getDefaultBranchName,
 } from 'netlify-cms-lib-util';
 
 import AuthenticationPage from './AuthenticationPage';
@@ -69,6 +70,7 @@ export default class GitHub implements Implementation {
     initialWorkflowStatus: string;
   };
   originRepo: string;
+  isBranchConfigured: boolean;
   repo?: string;
   openAuthoringEnabled: boolean;
   useOpenAuthoring?: boolean;
@@ -103,7 +105,7 @@ export default class GitHub implements Implementation {
     }
 
     this.api = this.options.API || null;
-
+    this.isBranchConfigured = config.backend.branch ? true : false;
     this.openAuthoringEnabled = config.backend.open_authoring || false;
     if (this.openAuthoringEnabled) {
       if (!this.options.useWorkflow) {
@@ -332,6 +334,19 @@ export default class GitHub implements Implementation {
       throw new Error('Your GitHub user account does not have access to this repo.');
     }
 
+    // Only set default branch name when the `branch` property is missing
+    // in the config file
+    if (!this.isBranchConfigured) {
+      const defaultBranchName = await getDefaultBranchName({
+        backend: 'github',
+        repo: this.originRepo,
+        token: this.token,
+      });
+      if (defaultBranchName) {
+        this.branch = defaultBranchName;
+      }
+    }
+
     // Authorized user
     return { ...user, token: state.token as string, useOpenAuthoring: this.useOpenAuthoring };
   }

packages/netlify-cms-backend-gitlab/src/__tests__/gitlab.spec.js

@@ -109,6 +109,7 @@ const resp = {
           access_level: 30,
         },
       },
+      default_branch: 'main',
     },
     readOnly: {
       permissions: {
@@ -194,7 +195,16 @@ describe('gitlab backend', () => {
       .reply(200, userResponse || resp.user.success);
 
     api
+      // The `authenticate` method of the API class from netlify-cms-backend-gitlab
+      // calls the same endpoint twice for gettng a single project.
+      // First time through `this.api.hasWriteAccess()
+      // Second time through the method `getDefaultBranchName` from lib-util
+      // As a result, we need to repeat the same response twice.
+      // Otherwise, we'll get an error: "No match for request to
+      // https://gitlab.com/api/v4"
+
       .get(expectedRepoUrl)
+      .times(2)
       .query(true)
       .reply(200, projectResponse || resp.project.success);
   }

packages/netlify-cms-backend-gitlab/src/implementation.ts

@@ -21,6 +21,7 @@ import {
   allEntriesByFolder,
   filterByExtension,
   branchFromContentKey,
+  getDefaultBranchName,
 } from 'netlify-cms-lib-util';
 
 import AuthenticationPage from './AuthenticationPage';
@@ -53,6 +54,7 @@ export default class GitLab implements Implementation {
     initialWorkflowStatus: string;
   };
   repo: string;
+  isBranchConfigured: boolean;
   branch: string;
   apiRoot: string;
   token: string | null;
@@ -84,6 +86,7 @@ export default class GitLab implements Implementation {
 
     this.repo = config.backend.repo || '';
     this.branch = config.backend.branch || 'master';
+    this.isBranchConfigured = config.backend.branch ? true : false;
     this.apiRoot = config.backend.api_root || 'https://gitlab.com/api/v4';
     this.token = '';
     this.squashMerges = config.backend.squash_merges || false;
@@ -150,6 +153,16 @@ export default class GitLab implements Implementation {
       throw new Error('Your GitLab user account does not have access to this repo.');
     }
 
+    if (!this.isBranchConfigured) {
+      const defaultBranchName = await getDefaultBranchName({
+        backend: 'gitlab',
+        repo: this.repo,
+        token: this.token,
+      });
+      if (defaultBranchName) {
+        this.branch = defaultBranchName;
+      }
+    }
     // Authorized user
     return { ...user, login: user.username, token: state.token as string };
   }

packages/netlify-cms-lib-util/src/API.ts

@@ -40,6 +40,26 @@ class RateLimitError extends Error {
   }
 }
 
+async function parseJsonResponse(response: Response) {
+  const json = await response.json();
+  if (!response.ok) {
+    return Promise.reject(json);
+  }
+  return json;
+}
+
+export function parseResponse(response: Response) {
+  const contentType = response.headers.get('Content-Type');
+  if (contentType && contentType.match(/json/)) {
+    return parseJsonResponse(response);
+  }
+  const textPromise = response.text().then(text => {
+    if (!response.ok) return Promise.reject(text);
+    return text;
+  });
+  return textPromise;
+}
+
 export async function requestWithBackoff(
   api: API,
   req: ApiRequest,
@@ -96,6 +116,140 @@ export async function requestWithBackoff(
   }
 }
 
+// Options is an object which contains all the standard network request properties
+// for modifying HTTP requests and may contains `params` property
+
+type Param = string | number;
+
+type ParamObject = Record<string, Param>;
+
+type HeaderObj = Record<string, string>;
+
+type HeaderConfig = {
+  headers?: HeaderObj;
+  token?: string | undefined;
+};
+
+type Backend = 'github' | 'gitlab' | 'bitbucket';
+
+// RequestConfig contains all the standard properties of a Request object and
+// several custom properties:
+// - "headers" property is an object whose properties and values are string types
+// - `token` property to allow passing tokens for users using a private repo.
+// - `params` property for customizing response
+// - `backend`(compulsory) to specify which backend to be used: Github, Gitlab etc.
+
+type RequestConfig = Omit<RequestInit, 'headers'> &
+  HeaderConfig & {
+    backend: Backend;
+    params?: ParamObject;
+  };
+
+export const apiRoots = {
+  github: 'https://api.github.com',
+  gitlab: 'https://gitlab.com/api/v4',
+  bitbucket: 'https://api.bitbucket.org/2.0',
+};
+
+export const endpointConstants = {
+  singleRepo: {
+    bitbucket: '/repositories',
+    github: '/repos',
+    gitlab: '/projects',
+  },
+};
+
+const api = {
+  buildRequest(req: ApiRequest) {
+    return req;
+  },
+};
+
+function constructUrlWithParams(url: string, params?: ParamObject) {
+  if (params) {
+    const paramList = [];
+    for (const key in params) {
+      paramList.push(`${key}=${encodeURIComponent(params[key])}`);
+    }
+    if (paramList.length) {
+      url += `?${paramList.join('&')}`;
+    }
+  }
+  return url;
+}
+
+async function constructRequestHeaders(headerConfig: HeaderConfig) {
+  const { token, headers } = headerConfig;
+  const baseHeaders: HeaderObj = { 'Content-Type': 'application/json; charset=utf-8', ...headers };
+  if (token) {
+    baseHeaders['Authorization'] = `token ${token}`;
+  }
+  return Promise.resolve(baseHeaders);
+}
+
+function handleRequestError(error: FetchError, responseStatus: number, backend: Backend) {
+  throw new APIError(error.message, responseStatus, backend);
+}
+
+export async function apiRequest(
+  path: string,
+  config: RequestConfig,
+  parser = (response: Response) => parseResponse(response),
+) {
+  const { token, backend, ...props } = config;
+  const options = { cache: 'no-cache', ...props };
+  const headers = await constructRequestHeaders({ headers: options.headers || {}, token });
+  const baseUrl = apiRoots[backend];
+  const url = constructUrlWithParams(`${baseUrl}${path}`, options.params);
+  let responseStatus = 500;
+  try {
+    const req = unsentRequest.fromFetchArguments(url, {
+      ...options,
+      headers,
+    }) as unknown as ApiRequest;
+    const response = await requestWithBackoff(api, req);
+    responseStatus = response.status;
+    const parsedResponse = await parser(response);
+    return parsedResponse;
+  } catch (error) {
+    return handleRequestError(error, responseStatus, backend);
+  }
+}
+
+export async function getDefaultBranchName(configs: {
+  backend: Backend;
+  repo: string;
+  token?: string;
+}) {
+  let apiPath;
+  const { token, backend, repo } = configs;
+  switch (backend) {
+    case 'gitlab': {
+      apiPath = `/projects/${encodeURIComponent(repo)}`;
+      break;
+    }
+    case 'bitbucket': {
+      apiPath = `/repositories/${repo}`;
+      break;
+    }
+    default: {
+      apiPath = `/repos/${repo}`;
+    }
+  }
+  const repoInfo = await apiRequest(apiPath, { token, backend });
+  let defaultBranchName;
+  if (backend === 'bitbucket') {
+    const {
+      mainbranch: { name },
+    } = repoInfo;
+    defaultBranchName = name;
+  } else {
+    const { default_branch } = repoInfo;
+    defaultBranchName = default_branch;
+  }
+  return defaultBranchName;
+}
+
 export async function readFile(
   id: string | null | undefined,
   fetchContent: () => Promise<string | Blob>,