node.js 函数调用顺序，Spotify Web API

Posted 2023-04-15

【中文标题】node.js 函数调用顺序，Spotify Web API

【英文标题】：node.js function call order, Spotify Web API

【发布时间】：2021-03-11 05:47:29

【问题描述】：

我正在尝试将 Spotify Web API 与 node.js 的包装器一起使用。在执行任何 API 调用之前，我需要设置访问令牌。在我的脚本中，我先调用setAccessToken 函数，然后在下面调用一些API 请求。但是，由于 node.js 的异步特性，我的 setAccessToken 方法在我的 API 请求之后被调用，这导致 API 请求失败。在调用下面的 API 请求之前，如何确保我的 setAccessToken 函数返回（API 请求行以 spotifyApi.getMySavedTracks 调用开头）

app.get('/callback', (req, res) => 
  var code = req.query.code || null;
  if (code === null) 
      console.log("code is null");
  

  async function authorize() 
    const data = await spotifyApi.authorizationCodeGrant(code);
    // console.log('The token expires in ' + data.body['expires_in']);
    // console.log('The access token is ' + data.body['access_token']);
    // console.log('The refresh token is ' + data.body['refresh_token']);
    // Set the access token on the API object to use it in later calls
    accesToken = data.body['access_token'];
    refreshToken = data.body['refresh_token'];
    spotifyApi.setAccessToken(accesToken);
    spotifyApi.setRefreshToken(refreshToken);
  

  try 
    authorize();
   catch (err) 
    console.log('Something went wrong!', err);
  

  spotifyApi.getMySavedTracks(
    limit : lim,
    offset: 1
  )
  .then(function(data) 
    return data.body.items;
  , function(err) 
    console.log('Something went wrong!', err);
  )
  .then(function(items) 
    let ids = [];
    items.forEach(function(item) 
      ids.push(item.track.id);
    )
    return spotifyApi.getAudioFeaturesForTracks(ids); //2xc8WSkjAp4xRGV6I1Aktb
  )
  .then(function(data) 
    let songs = data.body.audio_features;
    //console.log(songs);
    let filteredSongURIs = [];
    songs.forEach(function(song) 
      if ((song.energy >= moodScore-offset) && (song.energy <= moodScore+offset)) 
        filteredSongURIs.push(song.uri);
      
    )

    //Create Playlist with filtered songs
    spotifyApi.createPlaylist('Mooder Playlist',  'description': 'My description', 'public': true )
    .then(function(data) 
      return data.body.id;
    , function(err) 
      console.log('Something went wrong!', err);
    )
    .then(function(playlist) 
      spotifyApi.addTracksToPlaylist(playlist, filteredSongURIs)
    )
    .then(function(data) 
      console.log('Added tracks to playlist!');
    , function(err) 
      console.log('Something went wrong!', err);
    );
    
  , function(err) 
    console.log(err);
  );


  res.redirect('/testAPI');
);

【参考方案1】：

您可以将setAccessToken 之后的所有代码包装到另一个then 中，或者您可以将await 以Promise 结束：

// Add `async` here
app.get('/callback', async (req, res) => 
  var code = req.query.code || null;
  if (code === null) 
      console.log("code is null");
  
  try 
    const data = await spotifyApi.authorizationCodeGrant(code);
    // console.log('The token expires in ' + data.body['expires_in']);
    // console.log('The access token is ' + data.body['access_token']);
    // console.log('The refresh token is ' + data.body['refresh_token']);
    // Set the access token on the API object to use it in later calls
    accesToken = data.body['access_token'];
    refreshToken = data.body['refresh_token'];
    spotifyApi.setAccessToken(accesToken);
    spotifyApi.setRefreshToken(refreshToken);
   catch (err) 
    console.log('Something went wrong!', err);
  

  // The rest of your code

【讨论】：

原来spotifyApi.authorizationCodeGrant 不是异步函数。因为我得到了“SyntaxError: await is only valid in async function”@emi

问题不在于spotifyApi.authorizationCodeGrant，而在于调用它的函数需要声明为async才能被允许使用await。

我将所有代码放在异步函数中的 try 块中，并在 try 中调用它。但是我遇到了同样的问题

@Khashhogi 抱歉，我无法理解最后的评论。

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