Merge pull request #4 from intelligentpos/feature/get-name-from-tags-…

…with-prefix

add NamesFromTagWithPrefix method

README.md

@@ -31,7 +31,7 @@ go get github.com/intelligentpos/structextract
 		Field4: 123,
 	}
 
-    // Create a new extractor,we have to pass a pointer to a struct
+       //Create a new extractor,we have to pass a pointer to a struct
 	extract := New(&ss)
 
 
@@ -40,19 +40,25 @@ go get github.com/intelligentpos/structextract
 	values, _ := extract.Values()
 
 
-	//Names will return an array of the field names, []string
+	//Names will return a slice of the field names, []string
 	//["Field1","Field2","Field3","Field4"]
 	names, _ := extract.Names()
 
 
-	//NamesFromTag will return an array of the tag value for the given tag, map[string]interface{}
+	//NamesFromTag will return a slice of the tag value for the given tag, []string
 	//["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")
+        //ValuesFromTag will return a slice of the values of the fields with the give tag
+        //["value 1", "value 2", true]
+        valuesFromTag, _ := extract.ValuesFromTag("db")
+
+
+	//NamesFromTagWithPrefix will return a slice of the tag value for the given tag
+	//including the provided prefix, []string
+	//["default_field_1_db","default_field_2_db","default_field_3_db"]
+	tagwithprefix,_ := extract.NamesFromTagWithPrefix("db","default_")
 
 
 	//FieldValueMap will return a map of field name to value, map[string]interface{}

extract.go

@@ -3,6 +3,7 @@ package structextract
 import (
 	"errors"
 	"reflect"
+	"strings"
 )
 
 // Extractor holds the struct that we want to extract data from
@@ -59,6 +60,29 @@ func (e *Extractor) NamesFromTag(tag string) (out []string, err error) {
 	return
 }
 
+//NamesFromTagWithPrefix returns an array with all the tag names for each field including the given prefix
+func (e *Extractor) NamesFromTagWithPrefix(tag string, prefix string) (out []string, 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
+		}
+		val, ok := s.Type().Field(i).Tag.Lookup(tag)
+		if !ok {
+			continue
+		}
+		out = append(out, strings.TrimSpace(prefix+val))
+	}
+
+	return
+}
+
 //Values returns an interface array with all the values
 func (e *Extractor) Values() (out []interface{}, err error) {
 

extract_test.go

@@ -2,6 +2,7 @@ package structextract
 
 import (
 	"reflect"
+	"strings"
 	"testing"
 )
 
@@ -86,6 +87,59 @@ func TestExtractor_NamesFromTag_Invalid_Struct(t *testing.T) {
 
 }
 
+func TestExtractor_NamesFromTagWithPrefix(t *testing.T) {
+	ext := fakeData()
+	prefix := "default_"
+	res, err := ext.NamesFromTagWithPrefix("json", prefix)
+	if err != nil {
+		t.Fatalf("unexpected error")
+	}
+
+	if !strings.Contains(res[1], prefix) {
+		t.Fatalf("prefix was not applied")
+	}
+
+}
+
+func TestExtractor_NamesFromTagWithPrefix_Empty_Tag(t *testing.T) {
+
+	ext := fakeData()
+	prefix := "default_"
+	out, err := ext.NamesFromTagWithPrefix("", prefix)
+	if err != nil {
+		t.Fatalf("error should be null")
+	}
+	if len(out) != 0 {
+		t.Fatalf("no objects was expected")
+	}
+
+}
+func TestExtractor_NamesFromTagWithPrefix_No_Prefix(t *testing.T) {
+	ext := fakeData()
+	resWith, err := ext.NamesFromTagWithPrefix("json", "")
+	if err != nil {
+		t.Fatalf("unexpected error")
+	}
+	resWithOut, err := ext.NamesFromTag("json")
+	if err != nil {
+		t.Fatalf("unexpected error")
+	}
+
+	if !reflect.DeepEqual(resWith, resWithOut) {
+		t.Fatalf("slices micmatch")
+	}
+
+}
+
+func TestExtractor_NamesFromTagWithPrefix_InvalidStruct(t *testing.T) {
+	test := []string{"fail", "fail2"}
+	ext := New(&test)
+
+	_, err := ext.NamesFromTagWithPrefix("json", "default-")
+	if err == nil {
+		t.Fatal("Passed value is not a valid struct")
+	}
+}
 func TestExtractor_Values(t *testing.T) {
 	ext := fakeData()
 	exp := []interface{}{
@@ -243,6 +297,18 @@ func TestExtractor_GetFieldNamesFromTagIgnore(t *testing.T) {
 		t.FailNow()
 	}
 }
+func TestExtractor_GetFieldNamesFromTagWithPrefixIgnore(t *testing.T) {
+	ext := fakeIgnoredData()
+	exp := []string{
+		"default_field_1",
+		"default_field_3",
+	}
+	res, _ := ext.NamesFromTagWithPrefix("json", "default_")
+
+	if !reflect.DeepEqual(res, exp) {
+		t.FailNow()
+	}
+}
 
 func TestExtractor_ValuesIgnore(t *testing.T) {
 	ext := fakeIgnoredData()