◎ Improved handling of frames in v2tag! ◎

README.md

@@ -119,15 +119,12 @@ func main() {
        panic(err)
     }
 
-    if mp3tag.Header.Version == id3v2.V2_3 {
-        // get certain frame by identifier.
-        // Contents is []byte. CAN AND PROBABLY WILL
-        // CONTAIN NULL OR OTHER NON-PRINTABLE BYTES !!!
-        // Text encoding support is still not implemented. 
-        title := mp3tag.Frames["TIT2"].Contents
-        artist := mp3tag.Frames["TPE1"].Contents
-    }
-
+    // you can get some essential frames` contents from getters
+    title := tag.Title() // string
+    
+    // or get direct frame by id
+    commentFrame := tag.GetFrame("COMM") // *Frame 
+    // commentFrame.(Header.(...)|Contents)
 
     // etc.
 }

v2/frame_identifiers.go

@@ -2,7 +2,7 @@ package v2
 
 // from [https://id3.org/]
 
-var V2_2FrameIdentifiers  = map[string]string{
+var V2_2FrameIdentifiers = map[string]string{
 	"BUF": "Recommended buffer size",
 	"CNT": "Play counter",
 	"COM": "Comments",
@@ -232,3 +232,30 @@ var V2_4FrameIdentifiers = map[string]string{
 	"WPUB": "Publishers official webpage",
 	"WXXX": "User defined URL link frame",
 }
+
+// Searches for given ID3v2 frame identifier and returns its
+// description if found, else returns a ""
+func GetFIdentifierDescription(id string) string {
+	if len(id) == 3 {
+		// ID3v2.2.0 identifier
+		description, ok := V2_2FrameIdentifiers[id]
+		if !ok {
+			return ""
+		}
+		return description
+
+	} else if len(id) == 4 {
+		// ID3v2.(3|4).0 identifier
+		description, ok := V2_3FrameIdentifiers[id]
+		if !ok {
+			// not in v3, search in v4
+			description, ok = V2_4FrameIdentifiers[id]
+			if !ok {
+				return ""
+			}
+		}
+		return description
+	}
+
+	return ""
+}

v2/frame_identifiers_test.go

@@ -0,0 +1,24 @@
+package v2
+
+import "testing"
+
+func Test_GetFIdentifierDescription(t *testing.T) {
+	description := GetFIdentifierDescription("TIT2")
+
+	if description != "Title/songname/content description" {
+		t.Errorf("GetFIdentifierDescription failed: expected description for TIT2 to be %s, got %s",
+			"Title/songname/content description", description)
+	}
+
+	description = GetFIdentifierDescription("TBP")
+	if description != "BPM (Beats Per Minute)" {
+		t.Errorf("GetFIdentifierDescription failed: expected description for TBP to be %s, got %s",
+			"BPM (Beats Per Minute)", description)
+	}
+
+	description = GetFIdentifierDescription("SomeInvalidFrameIDName")
+	if description != "" {
+		t.Errorf("GetFIdentifierDescription failed: expected description for SomeInvalidFrameIDName to be \"\", got %s",
+			description)
+	}
+}

v2/read.go

@@ -34,14 +34,8 @@ func ReadV2Tag(rs io.ReadSeeker) (*ID3v2Tag, error) {
 		frames = append(frames, frame)
 	}
 
-	// create a map from collected frames
-	framesMp := make(map[string]Frame)
-	for _, frame := range frames {
-		framesMp[frame.Header.ID] = frame
-	}
-
 	return &ID3v2Tag{
 		Header: header,
-		Frames: framesMp,
+		Frames: frames,
 	}, nil
-}
+}

v2/read_test.go

@@ -19,10 +19,16 @@ func TestReadV2Tag(t *testing.T) {
 		t.Errorf("GetV2Tag failed: %s", err)
 	}
 
-	titleFrame := tag.Frames["TIT2"]
+	titleFrame := tag.GetFrame("TIT2")
 
 	if util.ToStringLossy(titleFrame.Contents) != "title" {
-		t.Errorf("ReadV2Tag failed: expected contents to be %s; got %s",
+		t.Errorf("ReadV2Tag failed: expected contents of the title frame to be %s; got %s",
 			"title", util.ToStringLossy(titleFrame.Contents))
 	}
+
+	album := tag.Album()
+	if album != "album" {
+		t.Errorf("ReadV2Tag failed: expected contents of the album to be %s; got %s",
+			"album", album)
+	}
 }

v2/v2tag.go

@@ -1,6 +1,69 @@
 package v2
 
+import "github.com/Unbewohnte/id3ed/util"
+
 type ID3v2Tag struct {
 	Header Header
-	Frames map[string]Frame
+	Frames []Frame
+}
+
+// Searches for frame with the same identifier as id in tag,
+// returns &it if found
+func (tag *ID3v2Tag) GetFrame(id string) *Frame {
+	for _, frame := range tag.Frames {
+		if frame.Header.ID == id {
+			return &frame
+		}
+	}
+	return nil
+}
+
+// Returns the contents for the title frame
+func (tag *ID3v2Tag) Title() string {
+	switch tag.Header.Version {
+	case V2_2:
+		return util.ToStringLossy(tag.GetFrame("TT2").Contents)
+	default:
+		return util.ToStringLossy(tag.GetFrame("TIT2").Contents)
+	}
+}
+
+// Returns the contents for the album frame
+func (tag *ID3v2Tag) Album() string {
+	switch tag.Header.Version {
+	case V2_2:
+		return util.ToStringLossy(tag.GetFrame("TAL").Contents)
+	default:
+		return util.ToStringLossy(tag.GetFrame("TALB").Contents)
+	}
+}
+
+// Returns the contents for the artist frame
+func (tag *ID3v2Tag) Artist() string {
+	switch tag.Header.Version {
+	case V2_2:
+		return util.ToStringLossy(tag.GetFrame("TP1").Contents)
+	default:
+		return util.ToStringLossy(tag.GetFrame("TPE1").Contents)
+	}
+}
+
+// Returns the contents for the year frame
+func (tag *ID3v2Tag) Year() string {
+	switch tag.Header.Version {
+	case V2_2:
+		return util.ToStringLossy(tag.GetFrame("TYE").Contents)
+	default:
+		return util.ToStringLossy(tag.GetFrame("TYER").Contents)
+	}
+}
+
+// Returns the contents for the comment frame
+func (tag *ID3v2Tag) Comment() string {
+	switch tag.Header.Version {
+	case V2_2:
+		return util.ToStringLossy(tag.GetFrame("COM").Contents)
+	default:
+		return util.ToStringLossy(tag.GetFrame("COMM").Contents)
+	}
 }