defaults skip if defined

Author: mcuadros

.travis.yml

@@ -1,5 +1,10 @@
 language: go
 
+go:
+  - 1.1
+  - 1.2
+  - tip
+
 script:
-  - go get github.com/mcuadros/go-defaults
+  - go get launchpad.net/gocheck
   - go test

defaults.go

@@ -5,12 +5,12 @@ import (
 	"strconv"
 )
 
-type Field struct {
+type fieldData struct {
 	Field reflect.StructField
 	Value reflect.Value
 }
 
-// Apply the default values to the struct object, the struct type must have
+// Applies the default values to the struct object, the struct type must have
 // the StructTag with name "default" and the directed value.
 //
 // Usage
@@ -27,23 +27,23 @@ func SetDefaults(variable interface{}) {
 	setDefaultValues(fields)
 }
 
-func getFields(variable interface{}) []*Field {
+func getFields(variable interface{}) []*fieldData {
 	valueObject := reflect.ValueOf(variable).Elem()
 
 	return getFieldsFromValue(valueObject)
 }
 
-func getFieldsFromValue(valueObject reflect.Value) []*Field {
+func getFieldsFromValue(valueObject reflect.Value) []*fieldData {
 	typeObject := valueObject.Type()
 
 	count := valueObject.NumField()
-	results := make([]*Field, 0)
+	results := make([]*fieldData, 0)
 	for i := 0; i < count; i++ {
 		value := valueObject.Field(i)
 		field := typeObject.Field(i)
 
 		if value.CanSet() {
-			results = append(results, &Field{
+			results = append(results, &fieldData{
 				Value: value,
 				Field: field,
 			})
@@ -53,13 +53,13 @@ func getFieldsFromValue(valueObject reflect.Value) []*Field {
 	return results
 }
 
-func setDefaultValues(fields []*Field) {
+func setDefaultValues(fields []*fieldData) {
 	for _, field := range fields {
 		setDefaultValue(field)
 	}
 }
 
-func setDefaultValue(field *Field) {
+func setDefaultValue(field *fieldData) {
 	defaultValue := field.Field.Tag.Get("default")
 
 	switch field.Value.Kind() {
@@ -80,37 +80,61 @@ func setDefaultValue(field *Field) {
 	}
 }
 
-func setDefaultValueToBool(field *Field, defaultValue string) {
+func setDefaultValueToBool(field *fieldData, defaultValue string) {
+	if field.Value.Bool() != false {
+		return
+	}
+
 	value, _ := strconv.ParseBool(defaultValue)
 	field.Value.SetBool(value)
 }
 
-func setDefaultValueToInt(field *Field, defaultValue string) {
+func setDefaultValueToInt(field *fieldData, defaultValue string) {
+	if field.Value.Int() != 0 {
+		return
+	}
+
 	value, _ := strconv.ParseInt(defaultValue, 10, 64)
 	field.Value.SetInt(value)
 }
 
-func setDefaultValueToFloat(field *Field, defaultValue string) {
+func setDefaultValueToFloat(field *fieldData, defaultValue string) {
+	if field.Value.Float() != .0 {
+		return
+	}
+
 	value, _ := strconv.ParseFloat(defaultValue, 64)
 	field.Value.SetFloat(value)
 }
 
-func setDefaultValueToUint(field *Field, defaultValue string) {
+func setDefaultValueToUint(field *fieldData, defaultValue string) {
+	if field.Value.Uint() != 0 {
+		return
+	}
+
 	value, _ := strconv.ParseUint(defaultValue, 10, 64)
 	field.Value.SetUint(value)
 }
 
-func setDefaultValueToSlice(field *Field, defaultValue string) {
+func setDefaultValueToSlice(field *fieldData, defaultValue string) {
 	if field.Value.Type().Elem().Kind() == reflect.Uint8 {
+		if field.Value.Bytes() != nil {
+			return
+		}
+
 		field.Value.SetBytes([]byte(defaultValue))
 	}
 }
 
-func setDefaultValueToString(field *Field, defaultValue string) {
+func setDefaultValueToString(field *fieldData, defaultValue string) {
+	if field.Value.String() != "" {
+		return
+	}
+
 	field.Value.SetString(defaultValue)
 }
 
-func setDefaultValueToStruct(field *Field, defaultValue string) {
+func setDefaultValueToStruct(field *fieldData, defaultValue string) {
 	fields := getFieldsFromValue(field.Value)
 	setDefaultValues(fields)
 }

defaults_test.go

@@ -70,3 +70,21 @@ func (self *DefaultsSuite) assertTypes(c *C, foo *ExampleBasic) {
 	c.Assert(foo.Float64, Equals, 6.4)
 	c.Assert(foo.Struct.Bool, Equals, true)
 }
+
+func (self *DefaultsSuite) TestSetDefaultsWithValues(c *C) {
+	foo := &ExampleBasic{
+		Integer:  55,
+		UInteger: 22,
+		Float32:  9.9,
+		String:   "bar",
+		Bytes:    []byte("foo"),
+	}
+
+	SetDefaults(foo)
+
+	c.Assert(foo.Integer, Equals, 55)
+	c.Assert(foo.UInteger, Equals, uint(22))
+	c.Assert(foo.Float32, Equals, float32(9.9))
+	c.Assert(foo.String, Equals, "bar")
+	c.Assert(string(foo.Bytes), Equals, "foo")
+}