Merge pull request #193 from zmb3/get-playlist-items-fix-local-tracks

Fix local tracks in GetPlaylistItems

.gitignore

@@ -15,3 +15,4 @@
 # vendor/
 
 .idea/
+.vscode/

README.md

@@ -90,3 +90,14 @@ Examples of the API can be found in the [examples](examples) directory.
 You may find tools such as [Spotify's Web API Console](https://developer.spotify.com/web-api/console/)
 or [Rapid API](https://rapidapi.com/package/SpotifyPublicAPI/functions?utm_source=SpotifyGitHub&utm_medium=button&utm_content=Vendor_GitHub)
 valuable for experimenting with the API.
+
+### Missing data in responses
+
+It's extremely common that when there is no market information available in your
+request, that the Spotify API will simply return null for details about a track
+or episode.
+
+This typically occurs when you are just using an application's auth token, and
+aren't impersonating a user via oauth. As when you are using a token associated
+with a user, the user's market seems to be extracted from their profile and
+used when producing the response.

examples/paging/page.go

@@ -2,11 +2,12 @@ package main
 
 import (
 	"context"
+	"log"
+	"os"
+
 	"github.com/zmb3/spotify/v2"
 	spotifyauth "github.com/zmb3/spotify/v2/auth"
 	"golang.org/x/oauth2/clientcredentials"
-	"log"
-	"os"
 )
 
 func main() {
@@ -24,14 +25,24 @@ func main() {
 	httpClient := spotifyauth.New().Client(ctx, token)
 	client := spotify.New(httpClient)
 
-	tracks, err := client.GetPlaylistTracks(ctx, "57qttz6pK881sjxj2TAEEo")
+	// Public playlist owned by noah.stride:
+	// "Long playlist for testing pagination"
+	playlistID := "1ckDytqUi4BUYzs6HIhcAN"
+	if id := os.Getenv("SPOTIFY_PLAYLIST"); id != "" {
+		playlistID = id
+	}
+
+	tracks, err := client.GetPlaylistItems(
+		ctx,
+		spotify.ID(playlistID),
+	)
 	if err != nil {
 		log.Fatal(err)
 	}
 
 	log.Printf("Playlist has %d total tracks", tracks.Total)
 	for page := 1; ; page++ {
-		log.Printf("  Page %d has %d tracks", page, len(tracks.Tracks))
+		log.Printf("  Page %d has %d tracks", page, len(tracks.Items))
 		err = client.NextPage(ctx, tracks)
 		if err == spotify.ErrNoMorePages {
 			break

playlist.go

@@ -209,36 +209,45 @@ type PlaylistItem struct {
 	Track PlaylistItemTrack `json:"track"`
 }
 
-// PlaylistItemTrack is a union type for both tracks and episodes.
+// PlaylistItemTrack is a union type for both tracks and episodes. If both
+// values are null, it's likely that the piece of content is not available in
+// the configured market.
 type PlaylistItemTrack struct {
 	Track   *FullTrack
 	Episode *EpisodePage
 }
 
 // UnmarshalJSON customises the unmarshalling based on the type flags set.
 func (t *PlaylistItemTrack) UnmarshalJSON(b []byte) error {
-	is := struct {
-		Episode bool `json:"episode"`
-		Track   bool `json:"track"`
+	// Spotify API will return `track: null`` where the content is not available
+	// in the specified market. We should respect this and just pass the null
+	// up...
+	if bytes.Equal(b, []byte("null")) {
+		return nil
+	}
+
+	itemType := struct {
+		Type string `json:"type"`
 	}{}
 
-	err := json.Unmarshal(b, &is)
+	err := json.Unmarshal(b, &itemType)
 	if err != nil {
 		return err
 	}
 
-	if is.Episode {
+	switch itemType.Type {
+	case "episode":
 		err := json.Unmarshal(b, &t.Episode)
 		if err != nil {
 			return err
 		}
-	}
-
-	if is.Track {
+	case "track":
 		err := json.Unmarshal(b, &t.Track)
 		if err != nil {
 			return err
 		}
+	default:
+		return fmt.Errorf("unrecognized item type: %s", itemType.Type)
 	}
 
 	return nil
@@ -470,17 +479,17 @@ func (c *Client) RemoveTracksFromPlaylistOpt(
 	ctx context.Context,
 	playlistID ID,
 	tracks []TrackToRemove,
-	snapshotID string) (newSnapshotID string, err error) {
-
+	snapshotID string,
+) (newSnapshotID string, err error) {
 	return c.removeTracksFromPlaylist(ctx, playlistID, tracks, snapshotID)
 }
 
 func (c *Client) removeTracksFromPlaylist(
 	ctx context.Context,
 	playlistID ID,
 	tracks interface{},
-	snapshotID string) (newSnapshotID string, err error) {
-
+	snapshotID string,
+) (newSnapshotID string, err error) {
 	m := make(map[string]interface{})
 	m["tracks"] = tracks
 	if snapshotID != "" {