Handle http method override with X-HTTP-Method-Override header. Fixes #8

endpoints-framework/src/main/java/com/google/api/server/spi/EndpointsServlet.java

@@ -28,6 +28,7 @@
 import com.google.common.collect.ImmutableList;
 
 import java.io.IOException;
+import java.util.Enumeration;
 import java.util.List;
 import java.util.Map.Entry;
 
@@ -61,19 +62,33 @@ public void init(ServletConfig config) throws ServletException {
 
   @Override
   public void service(HttpServletRequest request, HttpServletResponse response) throws IOException {
-    if ("OPTIONS".equals(request.getMethod())) {
+    String method = getRequestMethod(request);
+    if ("OPTIONS".equals(method)) {
       corsHandler.handle(request, response);
     } else {
       String path = Strings.stripSlash(
           request.getRequestURI().substring(request.getServletPath().length()));
-      EndpointsContext context = new EndpointsContext(request.getMethod(), path, request, response);
-      if (!dispatcher.dispatch(request.getMethod(), path, context)) {
+      EndpointsContext context = new EndpointsContext(method, path, request, response);
+      if (!dispatcher.dispatch(method, path, context)) {
         response.setStatus(HttpServletResponse.SC_NOT_FOUND);
         response.getWriter().append("Not Found");
       }
     }
   }
 
+  private String getRequestMethod(HttpServletRequest request) {
+    Enumeration headerNames = request.getHeaderNames();
+    String methodOverride = null;
+    while (headerNames.hasMoreElements()) {
+      String headerName = (String) headerNames.nextElement();
+      if (headerName.toLowerCase().equals("x-http-method-override")) {
+        methodOverride = request.getHeader(headerName);
+        break;
+      }
+    }
+    return methodOverride != null ? methodOverride.toUpperCase() : request.getMethod();
+  }
+
   private PathDispatcher<EndpointsContext> createDispatcher() {
     PathDispatcher.Builder<EndpointsContext> builder = PathDispatcher.builder();
     List<EndpointNode> endpoints = systemService.getEndpoints();

endpoints-framework/src/test/java/com/google/api/server/spi/EndpointsServletTest.java

@@ -113,6 +113,22 @@ public void echo() throws IOException {
     assertThat(actual.get("x").asInt()).isEqualTo(1);
   }
 
+  @Test
+  public void methodOverride() throws IOException {
+    req.setRequestURI("/_ah/api/test/v2/increment");
+    req.setMethod("POST");
+    req.addHeader("X-HTTP-Method-Override", "PATCH");
+    req.setParameter("x", "1");
+
+    servlet.service(req, resp);
+
+    assertThat(resp.getStatus()).isEqualTo(HttpServletResponse.SC_OK);
+    ObjectMapper mapper = ObjectMapperUtil.createStandardObjectMapper();
+    ObjectNode actual = mapper.readValue(resp.getContentAsString(), ObjectNode.class);
+    assertThat(actual.size()).isEqualTo(1);
+    assertThat(actual.get("x").asInt()).isEqualTo(2);
+  }
+
   @Test
   public void proxy() throws IOException {
     req.setRequestURI("/_ah/api/static/proxy.html");
@@ -157,5 +173,11 @@ public void empty() {}
     public TestResource echo(TestResource r) {
       return r;
     }
+
+    @ApiMethod(httpMethod = "PATCH")
+    public TestResource increment(TestResource r) {
+      r.x = r.x + 1;
+      return r;
+    }
   }
 }