Why is the Service Unavailable Error using Lapply? - r

Question

I am using the spotifyr library where I want to find audio features for multiple tracks. For example I can do this in order to find the audio features of a specific song using it's id.
analysis2 <- get_track_audio_features("2xLMifQCjDGFmkHkpNLD9h",
authorization = get_spotify_access_token())
Yesterday, I wrote this function below that takes all the tracks in a dataframe and finds the audio features for all of them and stores them in a list and it was working fine.
get_analysis <- function(track_id)
{
analysis <- get_track_audio_features(track_id,
authorization = get_spotify_access_token())
}
tracks_list <- lapply(all_tracks$track.id, get_analysis)
Now I am getting an error saying Request failed [503] and Error in get_track_audio_features(track_id, authorization = get_spotify_access_token()) : Service Unavailable (HTTP 503).
I am still able to find the audio features of a specific song so I am not sure which service is unavailable.

Answer 1

I suspect you are reaching a song in your data for which the response is denied from spotify. You could try adding an error-catching mechanism to see which one it is:
get_analysis <- function(track_id){
tryCatch(
expr = {
get_track_audio_features(track_id, authorization = get_spotify_access_token())
},
error = function(e){
print(track_id)
}) -> analysis
return(analysis)
}
tracks_list <- lapply(all_tracks$track.id, get_analysis)
I looked at the source code for the package and didn't see any sneaky rate-limiting issues and the Web API page shows error 503 as a generic error that needs waiting to be resolved (https://developer.spotify.com/documentation/web-api/). Thus you could also try just adding a 10 minute wait (I couldn't find how long exactly it is on Spotify's website):
get_analysis <- function(track_id){
tryCatch(
expr = {
get_track_audio_features(track_id, authorization = get_spotify_access_token()) -> output
return(output)
},
error = function(e){
print(track_id)
return(e)
}) -> output
}
wait.function <- funciton(){
Sys.sleep(600)
}
get_analysis_master <- function(all_tracks){
k <- 1
tracks_list <- list()
for(track.id in all_tracks$track.id){
get_analysis(track.id) -> output
if(!inherits(output, "error")){
tracks_list[[k]] <- output
k <- k + 1
} else {
wait.function()
}
return(tracks_list)
}
get_analysis_master(all_tracks) -> tracks_list