Reactjs 返回空json,即使它是';它不是空的
我试图将一个json返回给我的react客户端,其中包含一个歌曲(对象)列表。但它返回一个空数组作为json。这就是我检索数据的方式Reactjs 返回空json,即使它是';它不是空的,reactjs,express,sequelize.js,Reactjs,Express,Sequelize.js,我试图将一个json返回给我的react客户端,其中包含一个歌曲(对象)列表。但它返回一个空数组作为json。这就是我检索数据的方式 let songs = []; fetch("https://api.spotify.com/v1/me/tracks", { method: "GET", headers: { Authorization: "Bearer " + req.user.accessToken }, json: true })
let songs = [];
fetch("https://api.spotify.com/v1/me/tracks", {
method: "GET",
headers: {
Authorization: "Bearer " + req.user.accessToken
},
json: true
})
.then(res => res.json())
.then(apiResponse => {
let limit = apiResponse.limit;
for (let i = 0; i < limit; i++) {
Song.findOrCreate({
where: {
name: apiResponse.items[i].track.name,
song_spotify_id: apiResponse.items[i].track.id,
album: apiResponse.items[i].track.album.name,
popularity: apiResponse.items[i].track.popularity,
track_number: apiResponse.items[i].track.track_number,
uri: apiResponse.items[i].track.uri
}
}).then(song => {
songs.push(song);
});
}
})
.catch(function(error) {
return {
type: "ERROR ON FETCH",
api_response: { success: false }
};
});
console.log("songs: *********************" + songs);
res.status(200).json(songs);
});
奇怪的是,我有两个版本。其中一个版本就是这个版本,它只要求SpotifyAPI提供20首歌曲。我的另一个版本几乎完全相同,只是它循环并请求整个歌曲列表(获取50首、保存50首、请求spotify再获取50首,等等),而另一个版本可以工作。代码完全相同,但问题是加载需要很长时间,所以我试图简化它,但它不起作用
我感谢您提供的任何帮助。这是因为您必须等待所有承诺,然后才能发送回复 实际上,您发送了响应,但数据库中的查询过程尚未运行
let songs = [];
fetch("https://api.spotify.com/v1/me/tracks", {
method: "GET",
headers: {
Authorization: "Bearer " + req.user.accessToken
},
json: true
})
.then(results => results.json())
.then(apiResponse => {
let limit = apiResponse.limit;
let promises = [];
for (let i = 0; i < limit; i++) {
const myPromise = new Promise((resolve, reject) => {
Song.findOrCreate({
where: {
name: apiResponse.items[i].track.name,
song_spotify_id: apiResponse.items[i].track.id,
album: apiResponse.items[i].track.album.name,
popularity: apiResponse.items[i].track.popularity,
track_number: apiResponse.items[i].track.track_number,
uri: apiResponse.items[i].track.uri
}
}).then(song => {
songs.push(song);
resolve(true)
});
});
promises.push(myPromise);
}
Promise.all(promises)
.then(() => {
console.log("songs: *********************" + songs);
res.status(200).json(songs);
});
})
.catch(function(error) {
return {
type: "ERROR ON FETCH",
api_response: { success: false }
};
});
});
let songs=[];
取回(“https://api.spotify.com/v1/me/tracks", {
方法:“获取”,
标题:{
授权:“承载人”+req.user.accessToken
},
json:true
})
.then(results=>results.json())
。然后(apiResponse=>{
let limit=apiResponse.limit;
让承诺=[];
for(设i=0;i{
Song.findOrCreate({
其中:{
名称:apiResponse.items[i].track.name,
song_spotify_id:apiResponse.items[i].track.id,
唱片集:apiResponse.items[i].track.album.name,
流行度:apiResponse.items[i].track.popularity,
轨道号:apiResponse.items[i]。轨道号,
uri:apiResponse.items[i].track.uri
}
}).然后(歌曲=>{
歌曲。推(歌曲);
解析(真)
});
});
承诺。推动(我的承诺);
}
所有(承诺)
.然后(()=>{
console.log(“歌曲:****************”+歌曲);
res.status(200).json(歌曲);
});
})
.catch(函数(错误){
返回{
类型:“获取时出错”,
api_响应:{成功:错误}
};
});
});
[]
let songs = [];
fetch("https://api.spotify.com/v1/me/tracks", {
method: "GET",
headers: {
Authorization: "Bearer " + req.user.accessToken
},
json: true
})
.then(results => results.json())
.then(apiResponse => {
let limit = apiResponse.limit;
let promises = [];
for (let i = 0; i < limit; i++) {
const myPromise = new Promise((resolve, reject) => {
Song.findOrCreate({
where: {
name: apiResponse.items[i].track.name,
song_spotify_id: apiResponse.items[i].track.id,
album: apiResponse.items[i].track.album.name,
popularity: apiResponse.items[i].track.popularity,
track_number: apiResponse.items[i].track.track_number,
uri: apiResponse.items[i].track.uri
}
}).then(song => {
songs.push(song);
resolve(true)
});
});
promises.push(myPromise);
}
Promise.all(promises)
.then(() => {
console.log("songs: *********************" + songs);
res.status(200).json(songs);
});
})
.catch(function(error) {
return {
type: "ERROR ON FETCH",
api_response: { success: false }
};
});
});