我正在尝试通过我拥有的“事件”数据库，并根据每个事件的位置，半径，开始时间和结束时间从Instagram API中提取照片。我在我的节点服务器上设置了以下代码，但它的行为并不像我期望的那样。
我运行此代码时看到的第一件事是为每个事件打印sending request to Instagram for [name] with min_timestamp: [timestamp]。我没想到这一点。我本来希望看到第一个事件记录这一行，然后一遍又一遍地更新新的时间戳，直到该事件到达结束时间。然后是事件2，遍历时间戳，依此类推。
我最终会为每个事件反复重复相同的照片。这就好像我的代码一次又一次地向Instagram发送一个请求（带有初始时间戳）然后停止。
关于我的timestamp变量的注释：对于每个事件，我将minTimestamp变量设置为最初等于我的数据库中的event.start。这是在发送给Instagram的请求中使用的。 Instagram向我返回最多20张照片。每张照片都有一个created_time变量。我抓住了最新的created_time变量，并将我的minTimestamp变量设置为等于它（minTimestamp = images[0].created_time;），以便我下次发送到Instagram的请求（以获取接下来的20张照片）。这一过程一直持续到minTimestamp不再小于endTimestamp（来自我的db的那个事件的event.end）。
server.js代码：
// modules =================================================
var express = require('express.io');
var app = express();
var port = process.env.PORT || 6060;
var io = require('socket.io').listen(app.listen(port));
var request = require('request');
var Instagram = require('instagram-node-lib');
var mongoose = require('mongoose');
var async = require('async');
var bodyParser = require('body-parser');
var methodOverride = require('method-override');
var db = require('./config/db');
var Event = require('./app/models/event');
// configuration ===========================================
mongoose.connect(db.url); // connect to our mongoDB database
// get all data/stuff of the body (POST) parameters
app.use(bodyParser.json()); // parse application/json
app.use(bodyParser.json({ type: 'application/vnd.api+json' })); // parse application/vnd.api+json as json
app.use(bodyParser.urlencoded({ extended: true })); // parse application/x-www-form- urlencoded
app.use(methodOverride('X-HTTP-Method-Override')); // override with the X-HTTP-Method- Override header in the request. simulate DELETE/PUT
app.use(express.static(__dirname + '/public')); // set the static files location /public/img will be /img for users
var baseUrl = 'https://api.instagram.com/v1/media/search?lat=';
var clientId = CLIENT-ID;
Event.find({}, function(err, events) {
async.eachSeries(events, function(event, callback) {
var name = event.event;
var latitude = event.latitude;
var longitude = event.longitude;
var distance = event.radius;
var minTimestamp = Math.floor(new Date(event.start).getTime()/1000);
var endTimestamp = Math.floor(new Date(event.end).getTime()/1000);
async.whilst(
function () { return minTimestamp < Math.floor(Date.now() / 1000) && minTimestamp < endTimestamp; },
function(callback) {
console.log('sending request to Instagram for ' + name + ' with min_timestamp: ' + minTimestamp);
request(baseUrl + latitude + '&lng=' + longitude + '&distance=' + distance + '&min_timestamp=' + minTimestamp + '&client_id=' + clientId,
function (error, response, body) {
if (error) {
console.log('error');
return;
}
//JSON object with all the info about the image
var imageJson = JSON.parse(body);
var images = imageJson.data;
var numImages = images.length;
console.log(numImages + ' images returned with starting time ' + images[(numImages - 1)].created_time + ' and ending time ' + images[0].created_time);
async.eachSeries(images, function(image, callback) {
//Save the new object to DB
Event.findOneAndUpdate( { $and: [{latitude: latitude}, {radius: distance}] }, { $push: {'photos':
{ img: image.images.standard_resolution.url,
link: image.link,
username: image.user.username,
profile: image.user.profile_picture,
text: image.caption ? image.caption.text : '',
longitude: image.location.longitude,
latitude: image.location.latitude
}}},
{ safe: true, upsert: false },
function(err, model) {
console.log(err);
}
);
console.log(numImages + ' images saved to db');
callback();
}, function(err){
// if any of the file processing produced an error, err would equal that error
if( err ) {
// One of the iterations produced an error.
// All processing will now stop.
console.log('Images failed to process');
} else {
console.log('All images have been processed successfully');
}
});
minTimestamp = images[0].created_time;
console.log('min_timestamp incremented to: ' + minTimestamp);
}
);
},
function (err) {
}
);
callback();
}, function(err){
// if any of the file processing produced an error, err would equal that error
if( err ) {
// One of the iterations produced an error.
// All processing will now stop.
console.log('An event failed to process');
} else {
console.log('All events have been processed successfully');
}
});
});
// routes ==================================================
require('./app/routes')(app); // configure our routes
// start app ===============================================
console.log('Magic happens on port ' + port); // shoutout to the user
exports = module.exports = app; // expose app
答案 0 :(得分：1)
答案是你错过了对while位的回调（）。
以下是一些代码来说明：
var async = require('async');
var minTimestamp = 1;
var endTimestamp = 10;
async.whilst(
function () { minTimestamp < endTimestamp; },
function(callback) {
console.log('sending request to Instagram for name with min_timestamp: ' + minTimestamp);
minTimestamp = minTimestamp + 1;
console.log('min_timestamp incremented to: ' + minTimestamp);
callback();
},
function (err) {
if(err){
throw err;
}
}
);
如果我在没有callback()的情况下运行它，我会得到以下输出：
sending request to Instagram for name with min_timestamp: 1
min_timestamp incremented to: 2
如果我放回callback()，我会得到这个：
sending request to Instagram for name with min_timestamp: 1
min_timestamp incremented to: 2
sending request to Instagram for name with min_timestamp: 2
min_timestamp incremented to: 3
sending request to Instagram for name with min_timestamp: 3
min_timestamp incremented to: 4
sending request to Instagram for name with min_timestamp: 4
min_timestamp incremented to: 5
sending request to Instagram for name with min_timestamp: 5
min_timestamp incremented to: 6
sending request to Instagram for name with min_timestamp: 6
min_timestamp incremented to: 7
sending request to Instagram for name with min_timestamp: 7
min_timestamp incremented to: 8
sending request to Instagram for name with min_timestamp: 8
min_timestamp incremented to: 9
sending request to Instagram for name with min_timestamp: 9
min_timestamp incremented to: 10
因此在这里放一个callback（）：
minTimestamp = images[0].created_time;
console.log('min_timestamp incremented to: ' + minTimestamp);
callback(); //missing callback
}
);
},
答案 1 :(得分：0)
// modules =================================================
var express = require('express.io');
var app = express();
var port = process.env.PORT || 6060;
var io = require('socket.io').listen(app.listen(port));
var request = require('request');
var Instagram = require('instagram-node-lib');
var mongoose = require('mongoose');
var async = require('async');
var bodyParser = require('body-parser');
var methodOverride = require('method-override');
var db = require('./config/db');
var Event = require('./app/models/event');
// configuration ===========================================
mongoose.connect(db.url); // connect to our mongoDB database
// get all data/stuff of the body (POST) parameters
app.use(bodyParser.json()); // parse application/json
app.use(bodyParser.json({ type: 'application/vnd.api+json' })); // parse application/vnd.api+json as json
app.use(bodyParser.urlencoded({ extended: true })); // parse application/x-www-form- urlencoded
app.use(methodOverride('X-HTTP-Method-Override')); // override with the X-HTTP-Method- Override header in the request. simulate DELETE/PUT
app.use(express.static(__dirname + '/public')); // set the static files location /public/img will be /img for users
var baseUrl = 'https://api.instagram.com/v1/media/search?lat=';
var clientId = CLIENT-ID;
Event.find({}, function(err, events) {
async.eachSeries(events, function(event, seriesCallback) {
var name = event.event;
var latitude = event.latitude;
var longitude = event.longitude;
var distance = event.radius;
var minTimestamp = Math.floor(new Date(event.start).getTime()/1000);
var endTimestamp = Math.floor(new Date(event.end).getTime()/1000);
async.whilst(
function () { return minTimestamp < Math.floor(Date.now() / 1000) && minTimestamp < endTimestamp; },
function(requestFinishedCallback) {
console.log('sending request to Instagram for ' + name + ' with min_timestamp: ' + minTimestamp);
request(baseUrl + latitude + '&lng=' + longitude + '&distance=' + distance + '&min_timestamp=' + minTimestamp + '&client_id=' + clientId,
function (error, response, body) {
if (error) {
console.log('error');
return;
}
//JSON object with all the info about the image
var imageJson = JSON.parse(body);
var images = imageJson.data;
var numImages = images.length;
console.log(numImages + ' images returned with starting time ' + images[(numImages - 1)].created_time + ' and ending time ' + images[0].created_time);
async.eachSeries(images, function(image, imageFinishedCallback) {
//Save the new object to DB
Event.findOneAndUpdate( { $and: [{latitude: latitude}, {radius: distance}] }, { $push: {'photos':
{ img: image.images.standard_resolution.url,
link: image.link,
username: image.user.username,
profile: image.user.profile_picture,
text: image.caption ? image.caption.text : '',
longitude: image.location.longitude,
latitude: image.location.latitude
}}},
{ safe: true, upsert: false },
function(err, model) {
console.log(err);
console.log('Image processed');
imageFinishedCallback();
}
);
}, function(err){
// if any of the image processing produced an error, err would equal that error
if( err ) {
// One of the iterations produced an error.
// All processing will now stop.
console.log('Images failed to process');
} else {
minTimestamp = images[0].created_time;
console.log(numImages + ' images have been processed successfully and min_timestamp has been incremented to: ' + minTimestamp);
requestFinishedCallback();
}
});
}
);
}, function(err){
// if any of the image processing produced an error, err would equal that error
if( err ) {
// One of the iterations produced an error.
// All processing will now stop.
console.log('Event failed to process');
} else {
console.log(name + ' has been fully processed successfully with final min_timestamp of: ' + minTimestamp);
}
seriesCallback();
});
}, function(err){
// if any of the image processing produced an error, err would equal that error
if( err ) {
// One of the iterations produced an error.
// All processing will now stop.
console.log('Something failed to process');
} else {
console.log('All events have been processed successfully');
}
});
});
// routes ==================================================
require('./app/routes')(app); // configure our routes
// start app ===============================================
console.log('Magic happens on port ' + port); // shoutout to the user
exports = module.exports = app;