Javascript 管道数据一次读取';在Node.js中准备好了吗
我有一个大的JSON文件,如下所示:Javascript 管道数据一次读取';在Node.js中准备好了吗,javascript,node.js,pipe,geocoding,jsonstream,Javascript,Node.js,Pipe,Geocoding,Jsonstream,我有一个大的JSON文件,如下所示: [ { "id": 2000, "city": "New York", "lat": "", "lon": "", }, ... ] 我在寻找每个物体的纬度和经度。我正在使用JSONStream模块来传输数据: var writeStream = fs.createWriteStream('data/stream.json'); var readStream = fs.createReadStream('data/dummy/insti
[
{
"id": 2000,
"city": "New York",
"lat": "",
"lon": "",
},
...
]
我在寻找每个物体的纬度和经度。我正在使用JSONStream模块来传输数据:
var writeStream = fs.createWriteStream('data/stream.json');
var readStream = fs.createReadStream('data/dummy/institucion_1_2000.json', {encoding: 'utf8'})
// Search for lat and lon
var search = es.mapSync(function(data){
if(data.lat == ""){
// Search for the lat and lon
geocoder.geocode({address: data.city, country: "US"})
.then(function(res) {
console.log("Searched for " + res[0].formattedAddress);
data.lat = res[0].latitude;
data.lon = res[0].longitude;
})
.catch(function(err) {
console.log("There was an error with element with id = " + data.id);
console.log("Here is the error: " + err);
if(err == 'Error: Status is OVER_QUERY_LIMIT. You have exceeded your rate-limit for this API.') {
process.exit();
}
});
return data;
}
})
// Pipe
readStream
.pipe(JSONStream.parse('*'))
.pipe(search)
.pipe(JSONStream.stringify()) // This doesent wait until the search is finish
.pipe(writeStream)
地理编码部分工作正常
我的问题是,JSONStream.stringify在搜索函数结束之前读取并通过管道传输数据。所以我得到的是相同的JSON文件,没有需要的修改。如果我尝试一下:
if(data.lat == ""){
lat = 1;
}
与需要更多时间的地理编码不同,它是有效的。我猜我的问题在于修改数据流所需的时间。那么,有没有一种方法可以在数据被修改后对其进行管道化处理
编辑
我在同步和异步之间搞得一团糟。多亏了
您正在使用mapSync,但在其中执行异步操作?我尝试使用map(),但结果相同。有什么想法吗?你在.then()中调用回调了吗?是的!真管用!谢谢!
var search = es.map(function (data, callback) {
if(data.lat == ""){
geocoder.geocode({address: data.city, country: "USA"}) // Choose between Comuna_Empresa and Comuna_Institucion
.then(function(res) {
console.log("Searched for " + res[0].formattedAddress);
data.lat = res[0].latitude;
data.lon = res[0].longitude;
callback(null,data);
})
.catch(function(err) {
console.log("There was an error with element at index = " + index);
console.log("Here is the error: " + err);
});
}
})