Form method middleware

lib/http.dart

@@ -35,6 +35,7 @@ part 'src/http/middleware.dart';
 part 'src/http/middleware/csrf_middleware.dart';
 part 'src/http/middleware/input_middleware.dart';
 part 'src/http/middleware/static_files_middleware.dart';
+part 'src/http/middleware/form_method_middleware.dart';
 part 'src/http/router/route.dart';
 part 'src/http/router/route_group.dart';
 part 'src/http/router/router.dart';

lib/src/http/http_service_provider.dart

@@ -30,12 +30,14 @@ class HttpServiceProvider extends ServiceProvider {
        CsrfMiddleware csrfMiddleware,
        StaticFilesMiddleware staticFilesMiddleware,
        InputMiddleware inputMiddleware,
+       FormMethodMiddleware formMethodMiddleware,
        UrlGenerator urlGenerator) {
     _urlGenerator = urlGenerator;
 
     server.addMiddleware(sessionsMiddleware, highPriority: true);
     server.addMiddleware(staticFilesMiddleware);
     server.addMiddleware(inputMiddleware);
+    server.addMiddleware(formMethodMiddleware);
     server.addMiddleware(csrfMiddleware);
     server.onError = (e, s) {
       print('');

lib/src/http/middleware/form_method_middleware.dart

@@ -0,0 +1,29 @@
+part of bridge.http;
+
+class FormMethodMiddleware {
+  shelf.Handler innerHandler;
+
+  call(shelf.Handler innerHandler) {
+    this.innerHandler = innerHandler;
+    return _handleRequests;
+  }
+
+  _handleRequests(shelf.Request request) async {
+    shelf.Response response = await innerHandler(request);
+
+    return new shelf.Response(
+        response.statusCode,
+        body: _injectFormMethods(await response.readAsString()),
+        headers: response.headers,
+        context: response.context);
+  }
+
+  String _injectFormMethods(String body) {
+    const pattern = r'''(<form[^>]*?method=)(['"])(put|patch|update|delete)\2([^>]*>)''';
+    return body.replaceAllMapped(
+        new RegExp(pattern, caseSensitive: false), (m) {
+      return '${m[1]}${m[2]}POST${m[2]}${m[4]}'
+          "<input type='hidden' name='_method' value='${m[3].toUpperCase()}'>";
+    });
+  }
+}

test/http/request_test.dart

@@ -101,6 +101,28 @@ class RequestTest implements TestCase {
         equals("<form><input type='hidden' name='_token' value='id'></form>"));
   }
 
+  @test
+  it_injects_a_hidden_input_in_html_forms_with_http_method() async {
+    server.addMiddleware(new FormMethodMiddleware());
+    router.get('/', () => ""
+        "<form method='patch'></form>"
+        "<form method='delete'></form>"
+        "<form method='UPDATE'></form>"
+        "<form method='put'></form>");
+    var request = new shelf.Request('GET', new Uri.http('example.com', '/'));
+    shelf.Response response = await server.handle(request);
+    expect(await response.readAsString(),
+        equals(""
+            "<form method='POST'>"
+            "<input type='hidden' name='_method' value='PATCH'></form>"
+            "<form method='POST'>"
+            "<input type='hidden' name='_method' value='DELETE'></form>"
+            "<form method='POST'>"
+            "<input type='hidden' name='_method' value='UPDATE'></form>"
+            "<form method='POST'>"
+            "<input type='hidden' name='_method' value='PUT'></form>"));
+  }
+
   @test
   it_can_add_specific_middleware_for_a_route() async {
     router.post('/', () => 'response')