add feature nested pointer support(#21)

Author: zhlingbo

README.md

@@ -66,6 +66,83 @@ fmt.Println(example.Bar) //Prints: 0
 
 ```
 
+Pointer Set
+-------
+
+Pointer field struct is a tricky usage to avoid covering existed values. 
+
+Take the basic example in the above section and change it slightly:
+```go
+
+type ExamplePointer struct {
+    Foo *bool   `default:"true"` //<-- StructTag with a default key
+    Bar *string `default:"example"`
+    Qux *int    `default:"22"`
+    Oed *int64  `default:"64"`
+}
+
+...
+
+boolZero := false
+stringZero := ""
+intZero := 0
+example := &ExamplePointer{
+    Foo: &boolZero,
+    Bar: &stringZero,
+    Qux: &intZero,
+}
+defaults.SetDefaults(example)
+
+fmt.Println(*example.Foo) //Prints: false (zero value `false` for bool but not for bool ptr)
+fmt.Println(*example.Bar) //Prints: "" (print "" which set in advance, not "example" for default)
+fmt.Println(*example.Qux) //Prints: 0 (0 instead of 22)
+fmt.Println(*example.Oed) //Prints: 64 (64, because the ptr addr is nil when SetDefaults)
+
+```
+
+It's also a very useful feature for web application which default values are needed while binding request json.
+
+For example:
+```go
+type ExamplePostBody struct {
+    Foo *bool   `json:"foo" default:"true"` //<-- StructTag with a default key
+    Bar *string `json:"bar" default:"example"`
+    Qux *int    `json:"qux" default:"22"`
+    Oed *int64  `json:"oed" default:"64"`
+}
+```
+
+HTTP request seems like this:
+```bash
+curl --location --request POST ... \
+... \
+--header 'Content-Type: application/json' \
+--data-raw '{
+    "foo": false,
+    "bar": "",
+    "qux": 0
+}'
+```
+
+Request handler:
+```go
+func PostExampleHandler(c *gin.Context) {
+    var reqBody ExamplePostBody
+    if err := c.ShouldBindJSON(&reqBody); err != nil {
+        c.JSON(http.StatusBadRequest, nil)
+        return
+    }
+    defaults.SetDefaults(&reqBody)
+
+    fmt.Println(*reqBody.Foo) //Prints: false (zero value `false` for bool but not for bool ptr)
+    fmt.Println(*reqBody.Bar) //Prints: "" (print "" which set in advance, not "example" for default)
+    fmt.Println(*reqBody.Qux) //Prints: 0 (0 instead of 22, did not confused from whether zero value is in json or not)
+    fmt.Println(*reqBody.Oed) //Prints: 64 (In this case "oed" is not in req json, so set default 64)
+
+    ...
+}
+```
+
 License
 -------
 

defaults.go

@@ -12,15 +12,16 @@ import (
 // the StructTag with name "default" and the directed value.
 //
 // Usage
-//     type ExampleBasic struct {
-//         Foo bool   `default:"true"`
-//         Bar string `default:"33"`
-//         Qux int8
-//         Dur time.Duration `default:"2m3s"`
-//     }
 //
-//      foo := &ExampleBasic{}
-//      SetDefaults(foo)
+//	type ExampleBasic struct {
+//	    Foo bool   `default:"true"`
+//	    Bar string `default:"33"`
+//	    Qux int8
+//	    Dur time.Duration `default:"2m3s"`
+//	}
+//
+//	 foo := &ExampleBasic{}
+//	 SetDefaults(foo)
 func SetDefaults(variable interface{}) {
 	getDefaultFiller().Fill(variable)
 }
@@ -90,7 +91,11 @@ func newDefaultFiller() *Filler {
 	types := make(map[TypeHash]FillerFunc, 1)
 	types["time.Duration"] = func(field *FieldData) {
 		d, _ := time.ParseDuration(field.TagValue)
-		field.Value.Set(reflect.ValueOf(d))
+		if field.Value.Kind() == reflect.Ptr {
+			field.Value.Set(reflect.ValueOf(&d))
+		} else {
+			field.Value.Set(reflect.ValueOf(d))
+		}
 	}
 
 	funcs[reflect.Slice] = func(field *FieldData) {
@@ -107,6 +112,16 @@ func newDefaultFiller() *Filler {
 				fields := getDefaultFiller().GetFieldsFromValue(field.Value.Index(i), nil)
 				getDefaultFiller().SetDefaultValues(fields)
 			}
+		case reflect.Ptr:
+			count := field.Value.Len()
+			for i := 0; i < count; i++ {
+				if field.Value.Index(i).IsZero() {
+					newValue := reflect.New(field.Value.Index(i).Type().Elem())
+					field.Value.Index(i).Set(newValue)
+				}
+				fields := getDefaultFiller().GetFieldsFromValue(field.Value.Index(i).Elem(), nil)
+				getDefaultFiller().SetDefaultValues(fields)
+			}
 		default:
 			//处理形如 [1,2,3,4]
 			reg := regexp.MustCompile(`^\[(.*)\]$`)
@@ -134,6 +149,27 @@ func newDefaultFiller() *Filler {
 		}
 	}
 
+	funcs[reflect.Ptr] = func(field *FieldData) {
+		k := field.Value.Type().Elem().Kind()
+		if k != reflect.Struct && field.TagValue == "" {
+			return
+		}
+		if field.Value.IsNil() {
+			v := reflect.New(field.Value.Type().Elem())
+			field.Value.Set(v)
+		}
+		elemField := &FieldData{
+			Value: field.Value.Elem(),
+			Field: reflect.StructField{
+				Type: field.Field.Type.Elem(),
+				Tag:  field.Field.Tag,
+			},
+			TagValue: field.TagValue,
+			Parent:   nil,
+		}
+		funcs[field.Value.Elem().Kind()](elemField)
+	}
+
 	return &Filler{FuncByKind: funcs, FuncByType: types, Tag: "default"}
 }
 
@@ -159,13 +195,11 @@ func parseDateTimeString(data string) string {
 				case "date":
 					str := time.Now().AddDate(values[0], values[1], values[2]).Format("2006-01-02")
 					data = strings.Replace(data, match[0], str, -1)
-					break
 				case "time":
 					str := time.Now().Add((time.Duration(values[0]) * time.Hour) +
 						(time.Duration(values[1]) * time.Minute) +
 						(time.Duration(values[2]) * time.Second)).Format("15:04:05")
 					data = strings.Replace(data, match[0], str, -1)
-					break
 				}
 			}
 		}

defaults_test.go

@@ -32,6 +32,11 @@ type Child struct {
 	Age  int `default:"10"`
 }
 
+type ChildPtr struct {
+	Name *string
+	Age  *int `default:"10"`
+}
+
 type ExampleBasic struct {
 	Bool       bool    `default:"true"`
 	Integer    int     `default:"33"`
@@ -61,6 +66,27 @@ type ExampleBasic struct {
 	StringSliceSlice [][]string    `default:"[[1],[]]"`
 
 	DateTime string `default:"{{date:1,-10,0}} {{time:1,-5,10}}"`
+
+	BoolPtr     *bool          `default:"false"`
+	IntPtr      *int           `default:"33"`
+	Int8Ptr     *int8          `default:"8"`
+	Int16Ptr    *int16         `default:"16"`
+	Int32Ptr    *int32         `default:"32"`
+	Int64Ptr    *int64         `default:"64"`
+	UIntPtr     *uint          `default:"11"`
+	UInt8Ptr    *uint8         `default:"18"`
+	UInt16Ptr   *uint16        `default:"116"`
+	UInt32Ptr   *uint32        `default:"132"`
+	UInt64Ptr   *uint64        `default:"164"`
+	Float32Ptr  *float32       `default:"3.2"`
+	Float64Ptr  *float64       `default:"6.4"`
+	DurationPtr *time.Duration `default:"1s"`
+	SecondPtr   *time.Duration `default:"1s"`
+	StructPtr   *struct {
+		Bool    bool `default:"true"`
+		Integer *int `default:"33"`
+	}
+	ChildrenPtr []*ChildPtr
 }
 
 func (s *DefaultsSuite) TestSetDefaultsBasic(c *C) {
@@ -106,6 +132,24 @@ func (s *DefaultsSuite) assertTypes(c *C, foo *ExampleBasic) {
 	c.Assert(foo.IntSliceSlice, DeepEquals, [][]int{[]int{1}, []int{2}, []int{3}, []int{4}})
 	c.Assert(foo.StringSliceSlice, DeepEquals, [][]string{[]string{"1"}, []string{}})
 	c.Assert(foo.DateTime, Equals, "2020-08-10 12:55:10")
+	c.Assert(*foo.BoolPtr, Equals, false)
+	c.Assert(*foo.IntPtr, Equals, 33)
+	c.Assert(*foo.Int8Ptr, Equals, int8(8))
+	c.Assert(*foo.Int16Ptr, Equals, int16(16))
+	c.Assert(*foo.Int32Ptr, Equals, int32(32))
+	c.Assert(*foo.Int64Ptr, Equals, int64(64))
+	c.Assert(*foo.UIntPtr, Equals, uint(11))
+	c.Assert(*foo.UInt8Ptr, Equals, uint8(18))
+	c.Assert(*foo.UInt16Ptr, Equals, uint16(116))
+	c.Assert(*foo.UInt32Ptr, Equals, uint32(132))
+	c.Assert(*foo.UInt64Ptr, Equals, uint64(164))
+	c.Assert(*foo.Float32Ptr, Equals, float32(3.2))
+	c.Assert(*foo.Float64Ptr, Equals, 6.4)
+	c.Assert(*foo.DurationPtr, Equals, time.Second)
+	c.Assert(*foo.SecondPtr, Equals, time.Second)
+	c.Assert(foo.StructPtr.Bool, Equals, true)
+	c.Assert(*foo.StructPtr.Integer, Equals, 33)
+	c.Assert(foo.ChildrenPtr, IsNil)
 }
 
 func (s *DefaultsSuite) TestSetDefaultsWithValues(c *C) {
@@ -118,6 +162,13 @@ func (s *DefaultsSuite) TestSetDefaultsWithValues(c *C) {
 		Children: []Child{{Name: "alice"}, {Name: "bob", Age: 2}},
 	}
 
+	intzero := 0
+	foo.IntPtr = &intzero
+
+	ageZero := 0
+	childPtr := &ChildPtr{Age: &ageZero}
+	foo.ChildrenPtr = append(foo.ChildrenPtr, childPtr)
+
 	SetDefaults(foo)
 
 	c.Assert(foo.Integer, Equals, 55)
@@ -127,6 +178,10 @@ func (s *DefaultsSuite) TestSetDefaultsWithValues(c *C) {
 	c.Assert(string(foo.Bytes), Equals, "foo")
 	c.Assert(foo.Children[0].Age, Equals, 10)
 	c.Assert(foo.Children[1].Age, Equals, 2)
+	c.Assert(*foo.ChildrenPtr[0].Age, Equals, 0)
+	c.Assert(foo.ChildrenPtr[0].Name, IsNil)
+
+	c.Assert(*foo.IntPtr, Equals, 0)
 }
 
 func (s *DefaultsSuite) BenchmarkLogic(c *C) {

filler.go

@@ -82,11 +82,23 @@ func (f *Filler) isEmpty(field *FieldData) bool {
 			// always assume the structs in the slice is empty and can be filled
 			// the actually struct filling logic should take care of the rest
 			return true
+		case reflect.Ptr:
+			switch field.Value.Type().Elem().Elem().Kind() {
+			case reflect.Struct:
+				return true
+			default:
+				return field.Value.Len() == 0
+			}
 		default:
 			return field.Value.Len() == 0
 		}
 	case reflect.String:
 		return field.Value.String() == ""
+	case reflect.Ptr:
+		if field.Value.Type().Elem().Kind() == reflect.Struct {
+			return true
+		}
+		return field.Value.IsNil()
 	}
 	return true
 }
@@ -105,28 +117,26 @@ func (f *Filler) SetDefaultValue(field *FieldData) {
 			return
 		}
 	}
-
-	return
 }
 
 func (f *Filler) getFunctionByName(field *FieldData) FillerFunc {
-	if f, ok := f.FuncByName[field.Field.Name]; ok == true {
+	if f, ok := f.FuncByName[field.Field.Name]; ok {
 		return f
 	}
 
 	return nil
 }
 
 func (f *Filler) getFunctionByType(field *FieldData) FillerFunc {
-	if f, ok := f.FuncByType[GetTypeHash(field.Field.Type)]; ok == true {
+	if f, ok := f.FuncByType[GetTypeHash(field.Field.Type)]; ok {
 		return f
 	}
 
 	return nil
 }
 
 func (f *Filler) getFunctionByKind(field *FieldData) FillerFunc {
-	if f, ok := f.FuncByKind[field.Field.Type.Kind()]; ok == true {
+	if f, ok := f.FuncByKind[field.Field.Type.Kind()]; ok {
 		return f
 	}