Merge pull request #5 from intelligentpos/feature/get-values-from-tag…

…-support

Add support for extracting values of specific tagged struct fields

README.md

@@ -48,7 +48,12 @@ go get github.com/intelligentpos/structextract
 	//NamesFromTag will return an array of the tag value for the given tag, map[string]interface{}
 	//["field_1_db","field_2_db","field_3_db"]
 	tagnames, _ := extract.NamesFromTag("db")
-
+
+
+    //ValuesFromTag will return an array of the values of the fields with the give tag
+    //["value 1", "value 2", true]
+    valuesFromTag, _ := extract.ValuesFromTag("db")
+
 
 	//FieldValueMap will return a map of field name to value, map[string]interface{}
 	//{"Field1":"value 1","Field2":"value 2","Field3":true,"Field4":123}

extract.go

@@ -78,6 +78,27 @@ func (e *Extractor) Values() (out []interface{}, err error) {
 	return
 }
 
+//ValuesFromTag returns an interface array with all the values of fields with the given tag
+func (e *Extractor) ValuesFromTag(tag string) (out []interface{}, err error) {
+
+	if err := e.isValidStruct(); err != nil {
+		return nil, err
+	}
+
+	s := reflect.ValueOf(e.StructAddr).Elem()
+	for i := 0; i < s.NumField(); i++ {
+		if isIgnored(s.Type().Field(i).Name, e.ignoredFields) {
+			continue
+		}
+		if _, ok := s.Type().Field(i).Tag.Lookup(tag); ok {
+			out = append(out, s.Field(i).Interface())
+		}
+
+	}
+
+	return
+}
+
 // FieldValueMap returns a string to interface map,
 // key: field as defined on the struct
 // value: the value of the field

extract_test.go

@@ -6,8 +6,8 @@ import (
 )
 
 type testStruct struct {
-	Field1 string      `json:"field_1"`
-	Field2 string      `json:"field_2"`
+	Field1 string      `json:"field_1" db:"field1"`
+	Field2 string      `json:"field_2" db:"field2"`
 	Field3 bool        `json:"field_3"`
 	Field4 interface{} `json:"field_4"`
 }
@@ -112,6 +112,34 @@ func TestExtractor_Values_Invalid_Struct(t *testing.T) {
 
 }
 
+func TestExtractor_ValuesFromTag(t *testing.T) {
+	ext := fakeData().IgnoreField("Field4")
+	exp := []interface{}{
+		"hello",
+		"world",
+	}
+	res, _ := ext.ValuesFromTag("db")
+
+	expectedLength := len(exp)
+	if len(res) != expectedLength {
+		t.Fatalf("Number of values do not match: expected:%d, got:%d", expectedLength, len(res))
+	}
+
+	if !reflect.DeepEqual(res, exp) {
+		t.FailNow()
+	}
+}
+
+func TestExtractor_ValuesFromTag_Invalid_Struct(t *testing.T) {
+	test := []string{"fail", "fail2"}
+	ext := New(&test)
+
+	_, err := ext.ValuesFromTag("json")
+	if err == nil {
+		t.Fatal("Passed value is not a valid struct")
+	}
+}
+
 func TestExtractor_FieldValueMap(t *testing.T) {
 	ext := fakeData()
 	exp := map[string]interface{}{