[FIX] Issue 176 (#199)

* fix(request): change the order of the resource data check to prioritise the type when unmarshalling
- fixes #176

* tests(request): update the TestUnmarshalPayload_ptrsAllNil test that broke

* Using %v instead of %s

* Added a test case to demonstrate that this library follows the spec: covered the case where the incoming request payload is missing the `type` field, an error is expected.

Co-authored-by: Aren Patel <git@arenpatel.com>

request.go

@@ -175,10 +175,6 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 		}
 
 		if annotation == annotationPrimary {
-			if data.ID == "" {
-				continue
-			}
-
 			// Check the JSON API Type
 			if data.Type != args[1] {
 				er = fmt.Errorf(
@@ -189,6 +185,10 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 				break
 			}
 
+			if data.ID == "" {
+				continue
+			}
+
 			// ID will have to be transmitted as astring per the JSON API spec
 			v := reflect.ValueOf(data.ID)
 

request_test.go

@@ -70,11 +70,20 @@ func TestUnmarshalToStructWithPointerAttr(t *testing.T) {
 	}
 }
 
+func TestUnmarshalPayload_missingTypeFieldShouldError(t *testing.T) {
+	if err := UnmarshalPayload(
+		strings.NewReader(`{"data":{"body":"hello world"}}`),
+		&Post{},
+	); err == nil {
+		t.Fatalf("Expected an error but did not get one")
+	}
+}
+
 func TestUnmarshalPayload_ptrsAllNil(t *testing.T) {
 	out := new(WithPointer)
 	if err := UnmarshalPayload(
-		strings.NewReader(`{"data": {}}`), out); err != nil {
-		t.Fatalf("Error unmarshalling to Foo")
+		strings.NewReader(`{"data":{"type":"with-pointers"}}`), out); err != nil {
+		t.Fatalf("Error unmarshalling to Foo: %v", err)
 	}
 
 	if out.ID != nil {