Fix ID fields to accept both JSON strings and numbers

The Yandex Music API returns IDs as both JSON strings and numbers depending
on the endpoint. Added JSONID custom type in internal/models/base.go that
implements json.Unmarshaler to accept both formats and store as string.

Changed ID fields from string to JSONID:
- Track.ID, Major.ID, TrackLyricsInfo.ID (track.go)
- Album.ID, TrailerInfo.TrackID, TrailerInfo.AlbumID (album.go)

Updated example to convert JSONID to string when passing to client methods.

Co-Authored-By: Claude Code <noreply@anthropic.com>

internal/models/album.go

@@ -8,20 +8,20 @@ import (
 // Album represents a full album from the Yandex Music API.
 type Album struct {
 	BaseModel
-	ID          string     `json:"id"`
-	Title       string     `json:"title"`
-	CoverURI    string     `json:"cover_uri"`
-	Genre       string     `json:"genre"`
-	Year        int        `json:"year"`
-	TrackCount  int        `json:"track_count"`
-	Available   bool       `json:"available"`
-	ReleaseDate string     `json:"release_date"`
-	Artists     []Artist   `json:"artists"`
-	Labels      []Label    `json:"labels"`
-	Volumes     [][]Track  `json:"volumes"`
-	Description string     `json:"description"`
-	Meta        *AlbumMeta `json:"meta"`
-	Best        *Best      `json:"best"`
+	ID          JSONID      `json:"id"`
+	Title       string      `json:"title"`
+	CoverURI    string      `json:"cover_uri"`
+	Genre       string      `json:"genre"`
+	Year        int         `json:"year"`
+	TrackCount  int         `json:"track_count"`
+	Available   bool        `json:"available"`
+	ReleaseDate string      `json:"release_date"`
+	Artists     []Artist    `json:"artists"`
+	Labels      []Label     `json:"labels"`
+	Volumes     [][]Track   `json:"volumes"`
+	Description string      `json:"description"`
+	Meta        *AlbumMeta  `json:"meta"`
+	Best        *Best       `json:"best"`
 	// Additional fields
 	Region                       string          `json:"region"`
 	AvailableForPremiumUsers     bool            `json:"available_for_premium_users"`
@@ -226,8 +226,8 @@ type Best struct {
 type TrailerInfo struct {
 	BaseModel
 	PreviewURI string `json:"preview_uri"`
-	TrackID    string `json:"track_id"`
-	AlbumID    string `json:"album_id"`
+	TrackID    JSONID `json:"track_id"`
+	AlbumID    JSONID `json:"album_id"`
 	Duration   int    `json:"duration"`
 }
 

internal/models/base.go

@@ -4,6 +4,8 @@ package models
 
 import (
 	"encoding/json"
+	"fmt"
+	"strconv"
 
 	"gitea.mrixs.me/Mrixs/yandex-music-api-go/internal/utils"
 )
@@ -81,3 +83,30 @@ func (b *BaseModel) SetClient(c ClientInterface) {
 func (b *BaseModel) GetClient() ClientInterface {
 	return b.Client
 }
+
+// JSONID is an ID that can be represented as either a JSON string or a JSON number.
+// The Yandex Music API sometimes returns IDs as numbers (e.g., 12345) and sometimes
+// as strings (e.g., "12345"). JSONID accepts both and stores the value as a string.
+type JSONID string
+
+// UnmarshalJSON implements json.Unmarshaler, accepting both JSON strings and numbers.
+func (id *JSONID) UnmarshalJSON(data []byte) error {
+	// Try string first
+	var s string
+	if err := json.Unmarshal(data, &s); err == nil {
+		*id = JSONID(s)
+		return nil
+	}
+	// Try number (float64 is the default JSON number decoding)
+	var f float64
+	if err := json.Unmarshal(data, &f); err != nil {
+		return fmt.Errorf("cannot unmarshal %v into JSONID: %w", string(data), err)
+	}
+	*id = JSONID(strconv.FormatFloat(f, 'f', -1, 64))
+	return nil
+}
+
+// String returns the ID as a Go string.
+func (id JSONID) String() string {
+	return string(id)
+}

internal/models/track.go

@@ -8,7 +8,7 @@ import (
 // Track represents a full track from the Yandex Music API.
 type Track struct {
 	BaseModel
-	ID                       string           `json:"id"`
+	ID                       JSONID           `json:"id"`
 	Title                    string           `json:"title"`
 	DurationMs               int              `json:"duration_ms"`
 	StorageID                string           `json:"storage_id"`
@@ -149,14 +149,14 @@ func (t *Track) GetDownloadInfo(quality string) *DownloadInfo {
 
 // Major represents major label info for a track.
 type Major struct {
-	ID          string `json:"id"`
+	ID          JSONID `json:"id"`
 	Name        string `json:"name"`
 	Description string `json:"description"`
 }
 
 // TrackLyricsInfo represents minimal lyrics info for a track.
 type TrackLyricsInfo struct {
-	ID        string `json:"id"`
+	ID        JSONID `json:"id"`
 	Text      string `json:"text"`
 	Major     *Major `json:"major"`
 	Available bool   `json:"available"`