Add user locale api-fetch middleware

packages/api-fetch/CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 2.1.0 (Unreleased)
 
 - Support `per_page=-1` paginated requests.
+- Added new middleware to append `?_locale=user` to API requests ([#10862](https://github.com/WordPress/gutenberg/pull/10862)).
 
 ## 2.0.0 (2018-09-05)
 

packages/api-fetch/src/index.js

@@ -12,6 +12,7 @@ import createPreloadingMiddleware from './middlewares/preloading';
 import fetchAllMiddleware from './middlewares/fetch-all-middleware';
 import namespaceEndpointMiddleware from './middlewares/namespace-endpoint';
 import httpV1Middleware from './middlewares/http-v1';
+import userLocaleMiddleware from './middlewares/user-locale';
 
 const middlewares = [];
 
@@ -109,6 +110,7 @@ function apiFetch( options ) {
 		fetchAllMiddleware,
 		httpV1Middleware,
 		namespaceEndpointMiddleware,
+		userLocaleMiddleware,
 		...middlewares,
 	].reverse();
 

packages/api-fetch/src/middlewares/test/user-locale.js

@@ -0,0 +1,126 @@
+/**
+ * Internal dependencies
+ */
+import userLocaleMiddleware from '../user-locale';
+
+describe( 'User locale middleware', () => {
+	it( 'should append the _locale parameter to the path', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			path: '/wp/v2/posts',
+		};
+
+		const callback = ( options ) => {
+			expect( options.path ).toBe( '/wp/v2/posts?_locale=user' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'should append the _locale parameter to path with existing query argument', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			path: '/wp/v2/posts?foo=bar',
+		};
+
+		const callback = ( options ) => {
+			expect( options.path ).toBe( '/wp/v2/posts?foo=bar&_locale=user' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'does not modify existing single _locale parameter in path', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			path: '/wp/v2/posts?_locale=foo',
+		};
+
+		const callback = ( options ) => {
+			expect( options.path ).toBe( '/wp/v2/posts?_locale=foo' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'does not modify existing _locale parameter in path', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			path: '/wp/v2/posts?foo=bar&_locale=foo',
+		};
+
+		const callback = ( options ) => {
+			expect( options.path ).toBe( '/wp/v2/posts?foo=bar&_locale=foo' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'should append the _locale parameter to the url', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			url: 'http://wp.org/wp-json/wp/v2/posts',
+		};
+
+		const callback = ( options ) => {
+			expect( options.url ).toBe( 'http://wp.org/wp-json/wp/v2/posts?_locale=user' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'should append the _locale parameter to url with existing query argument', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			url: 'http://wp.org/wp-json/wp/v2/posts?foo=bar',
+		};
+
+		const callback = ( options ) => {
+			expect( options.url ).toBe( 'http://wp.org/wp-json/wp/v2/posts?foo=bar&_locale=user' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'does not modify existing single _locale parameter in url', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			url: 'http://wp.org/wp-json/wp/v2/posts?_locale=foo',
+		};
+
+		const callback = ( options ) => {
+			expect( options.url ).toBe( 'http://wp.org/wp-json/wp/v2/posts?_locale=foo' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+
+	it( 'does not modify existing _locale parameter in url', () => {
+		expect.hasAssertions();
+
+		const requestOptions = {
+			method: 'GET',
+			url: 'http://wp.org/wp-json/wp/v2/posts?foo=bar&_locale=foo',
+		};
+
+		const callback = ( options ) => {
+			expect( options.url ).toBe( 'http://wp.org/wp-json/wp/v2/posts?foo=bar&_locale=foo' );
+		};
+
+		userLocaleMiddleware( requestOptions, callback );
+	} );
+} );

packages/api-fetch/src/middlewares/user-locale.js

@@ -0,0 +1,26 @@
+/**
+ * WordPress dependencies
+ */
+import { addQueryArgs } from '@wordpress/url';
+
+function userLocaleMiddleware( options, next ) {
+	if (
+		typeof options.url === 'string' &&
+		-1 === options.url.indexOf( '?_locale=' ) &&
+		-1 === options.url.indexOf( '&_locale=' )
+	) {
+		options.url = addQueryArgs( options.url, { _locale: 'user' } );
+	}
+
+	if (
+		typeof options.path === 'string' &&
+		-1 === options.path.indexOf( '?_locale=' ) &&
+		-1 === options.path.indexOf( '&_locale=' )
+	) {
+		options.path = addQueryArgs( options.path, { _locale: 'user' } );
+	}
+
+	return next( options, next );
+}
+
+export default userLocaleMiddleware;