Support pointers as attrs (#40)

* add support to unmarshal attributes to struct field that are ptr types

* Spacing, addressed all the linter warnings, comments to describe errors, cleanup, left a TODO note to resolve the Error messaging.

request.go

@@ -12,16 +12,27 @@ import (
 	"time"
 )
 
-const unsuportedStructTagMsg = "Unsupported jsonapi tag annotation, %s"
-
-var (
-	ErrInvalidTime            = errors.New("Only numbers can be parsed as dates, unix timestamps")
-	ErrUnknownFieldNumberType = errors.New("The struct field was not of a known number type")
+const (
+	unsuportedStructTagMsg = "Unsupported jsonapi tag annotation, %s"
+	clientIDAnnotation     = "client-id"
 )
 
-// Convert an io into a struct instance using jsonapi tags on struct fields.
-// Method supports single request payloads only, at the moment. Bulk creates and updates
-// are not supported yet.
+var (
+	// ErrInvalidTime is returned when a struct has a time.Time type field, but
+	// the JSON value was not a unix timestamp integer.
+	ErrInvalidTime = errors.New("Only numbers can be parsed as dates, unix timestamps")
+	// ErrUnknownFieldNumberType is returned when the JSON value was a float
+	// (numeric) but the Struct field was a non numeric type (i.e. not int, uint,
+	// float, etc)
+	ErrUnknownFieldNumberType = errors.New("The struct field was not of a known number type")
+	// ErrUnsupportedPtrType is returned when the Struct field was a pointer but
+	// the JSON value was of a different type
+	ErrUnsupportedPtrType = errors.New("Pointer type in struct is not supported")
+)
+
+// UnmarshalPayload converts an io into a struct instance using jsonapi tags on
+// struct fields. This method supports single request payloads only, at the
+// moment. Bulk creates and updates are not supported yet.
 //
 // Will Unmarshal embedded and sideloaded payloads.  The latter is only possible if the
 // object graph is complete.  That is, in the "relationships" data there are type and id,
@@ -67,10 +78,8 @@ func UnmarshalPayload(in io.Reader, model interface{}) error {
 		}
 
 		return unmarshalNode(payload.Data, reflect.ValueOf(model), &includedMap)
-	} else {
-		return unmarshalNode(payload.Data, reflect.ValueOf(model), nil)
 	}
-
+	return unmarshalNode(payload.Data, reflect.ValueOf(model), nil)
 }
 
 func UnmarshalManyPayload(in io.Reader, t reflect.Type) ([]interface{}, error) {
@@ -98,7 +107,8 @@ func UnmarshalManyPayload(in io.Reader, t reflect.Type) ([]interface{}, error) {
 		}
 
 		return models, nil
-	} else {
+	}
+
 	var models []interface{}
 
 	for _, data := range payload.Data {
@@ -111,8 +121,6 @@ func UnmarshalManyPayload(in io.Reader, t reflect.Type) ([]interface{}, error) {
 	}
 
 	return models, nil
-	}
-
 }
 
 func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node) (err error) {
@@ -145,7 +153,8 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 
 		annotation := args[0]
 
-		if (annotation == "client-id" && len(args) != 1) || (annotation != "client-id" && len(args) < 2) {
+		if (annotation == clientIDAnnotation && len(args) != 1) ||
+			(annotation != clientIDAnnotation && len(args) < 2) {
 			er = ErrBadJSONAPIStructTag
 			break
 		}
@@ -173,7 +182,7 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 				er = ErrBadJSONAPIID
 				break
 			}
-		} else if annotation == "client-id" {
+		} else if annotation == clientIDAnnotation {
 			if data.ClientID == "" {
 				continue
 			}
@@ -194,6 +203,7 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 
 			v := reflect.ValueOf(val)
 
+			// Handle field of type time.Time
 			if fieldValue.Type() == reflect.TypeOf(time.Time{}) {
 				var at int64
 
@@ -244,8 +254,8 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 				continue
 			}
 
+			// JSON value was a float (numeric)
 			if v.Kind() == reflect.Float64 {
-				// Handle JSON numeric case
 				floatValue := v.Interface().(float64)
 
 				// The field may or may not be a pointer to a numeric; the kind var
@@ -297,6 +307,8 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 					n := float64(floatValue)
 					numericValue = reflect.ValueOf(&n)
 				default:
+					// We had a JSON float (numeric), but our field was a non numeric
+					// type
 					er = ErrUnknownFieldNumberType
 					break
 				}
@@ -309,7 +321,40 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 
 				continue
 			}
+
+			// Field was a Pointer type
+			if fieldValue.Kind() == reflect.Ptr {
+				var concreteVal reflect.Value
+
+				switch cVal := val.(type) {
+				case string:
+					concreteVal = reflect.ValueOf(&cVal)
+				case bool:
+					concreteVal = reflect.ValueOf(&cVal)
+				case complex64:
+					concreteVal = reflect.ValueOf(&cVal)
+				case complex128:
+					concreteVal = reflect.ValueOf(&cVal)
+				case uintptr:
+					concreteVal = reflect.ValueOf(&cVal)
+				default:
+					er = ErrUnsupportedPtrType
+					break
+				}
+
+				if fieldValue.Type() != concreteVal.Type() {
+					// TODO: use fmt.Errorf so that you can have a more informative
+					// message that reports the attempted type that was not supported.
+					er = ErrUnsupportedPtrType
+					break
+				}
+
+				fieldValue.Set(concreteVal)
+				continue
+			}
+
 			fieldValue.Set(reflect.ValueOf(val))
+
 		} else if annotation == "relation" {
 			isSlice := fieldValue.Type().Kind() == reflect.Slice
 
@@ -331,7 +376,11 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 				for _, n := range data {
 					m := reflect.New(fieldValue.Type().Elem().Elem())
 
-					if err := unmarshalNode(fullNode(n, included), m, included); err != nil {
+					if err := unmarshalNode(
+						fullNode(n, included),
+						m,
+						included,
+					); err != nil {
 						er = err
 						break
 					}
@@ -345,12 +394,18 @@ func unmarshalNode(data *Node, model reflect.Value, included *map[string]*Node)
 
 				buf := bytes.NewBuffer(nil)
 
-				json.NewEncoder(buf).Encode(data.Relationships[args[1]])
+				json.NewEncoder(buf).Encode(
+					data.Relationships[args[1]],
+				)
 				json.NewDecoder(buf).Decode(relationship)
 
 				m := reflect.New(fieldValue.Type().Elem())
 
-				if err := unmarshalNode(fullNode(relationship.Data, included), m, included); err != nil {
+				if err := unmarshalNode(
+					fullNode(relationship.Data, included),
+					m,
+					included,
+				); err != nil {
 					er = err
 					break
 				}

request_test.go

@@ -13,6 +13,94 @@ type BadModel struct {
 	ID int `jsonapi:"primary"`
 }
 
+type WithPointer struct {
+	ID       string   `jsonapi:"primary,with-pointers"`
+	Name     *string  `jsonapi:"attr,name"`
+	IsActive *bool    `jsonapi:"attr,is-active"`
+	IntVal   *int     `jsonapi:"attr,int-val"`
+	FloatVal *float32 `jsonapi:"attr,float-val"`
+}
+
+func TestUnmarshalToStructWithPointerAttr(t *testing.T) {
+	out := new(WithPointer)
+	in := map[string]interface{}{
+		"name":      "The name",
+		"is-active": true,
+		"int-val":   8,
+		"float-val": 1.1,
+	}
+	if err := UnmarshalPayload(sampleWithPointerPayload(in), out); err != nil {
+		t.Fatal(err)
+	}
+	if *out.Name != "The name" {
+		t.Fatalf("Error unmarshalling to string ptr")
+	}
+	if *out.IsActive != true {
+		t.Fatalf("Error unmarshalling to bool ptr")
+	}
+	if *out.IntVal != 8 {
+		t.Fatalf("Error unmarshalling to int ptr")
+	}
+	if *out.FloatVal != 1.1 {
+		t.Fatalf("Error unmarshalling to float ptr")
+	}
+}
+
+func TestUnmarshalToStructWithPointerAttr_AbsentVal(t *testing.T) {
+	out := new(WithPointer)
+	in := map[string]interface{}{
+		"name":      "The name",
+		"is-active": true,
+	}
+
+	if err := UnmarshalPayload(sampleWithPointerPayload(in), out); err != nil {
+		t.Fatalf("Error unmarshalling to Foo")
+	}
+
+	// these were present in the payload -- expect val to be not nil
+	if out.Name == nil || out.IsActive == nil {
+		t.Fatalf("Error unmarshalling; expected ptr to be not nil")
+	}
+
+	// these were absent in the payload -- expect val to be nil
+	if out.IntVal != nil || out.FloatVal != nil {
+		t.Fatalf("Error unmarshalling; expected ptr to be nil")
+	}
+}
+
+func TestStringPointerField(t *testing.T) {
+	// Build Book payload
+	description := "Hello World!"
+	data := map[string]interface{}{
+		"data": map[string]interface{}{
+			"type": "books",
+			"id":   "5",
+			"attributes": map[string]interface{}{
+				"author":      "aren55555",
+				"description": description,
+				"isbn":        "",
+			},
+		},
+	}
+	payload, err := json.Marshal(data)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Parse JSON API payload
+	book := new(Book)
+	if err := UnmarshalPayload(bytes.NewReader(payload), book); err != nil {
+		t.Fatal(err)
+	}
+
+	if book.Description == nil {
+		t.Fatal("Was not expecting a nil pointer for book.Description")
+	}
+	if expected, actual := description, *book.Description; expected != actual {
+		t.Fatalf("Was expecting descript to be `%s`, got `%s`", expected, actual)
+	}
+}
+
 func TestMalformedTag(t *testing.T) {
 	out := new(BadModel)
 	err := UnmarshalPayload(samplePayload(), out)
@@ -264,6 +352,7 @@ func samplePayloadWithoutIncluded() (result []byte, err error) {
 			},
 		},
 	}
+
 	result, err = json.Marshal(data)
 	return
 }
@@ -333,7 +422,6 @@ func samplePayload() io.Reader {
 	}
 
 	out := bytes.NewBuffer(nil)
-
 	json.NewEncoder(out).Encode(payload)
 
 	return out
@@ -352,7 +440,21 @@ func samplePayloadWithID() io.Reader {
 	}
 
 	out := bytes.NewBuffer(nil)
+	json.NewEncoder(out).Encode(payload)
 
+	return out
+}
+
+func sampleWithPointerPayload(m map[string]interface{}) io.Reader {
+	payload := &OnePayload{
+		Data: &Node{
+			ID:         "2",
+			Type:       "with-pointers",
+			Attributes: m,
+		},
+	}
+
+	out := bytes.NewBuffer(nil)
 	json.NewEncoder(out).Encode(payload)
 
 	return out
@@ -440,7 +542,6 @@ func sampleSerializedEmbeddedTestModel() *Blog {
 	MarshalOnePayloadEmbedded(out, testModel())
 
 	blog := new(Blog)
-
 	UnmarshalPayload(out, blog)
 
 	return blog

response_test.go

@@ -41,6 +41,7 @@ type Book struct {
 	Author      string  `jsonapi:"attr,author"`
 	ISBN        string  `jsonapi:"attr,isbn"`
 	Title       string  `jsonapi:"attr,title,omitempty"`
+	Description *string `jsonapi:"attr,description"`
 	Pages       *uint   `jsonapi:"attr,pages,omitempty"`
 	PublishedAt time.Time
 }