Node.js "Callback is already called"。但是没有任何其他回调

Question

整天都在找论坛，还是解决不了我的问题。我正在使用 NodeJS 和 async.waterfall 发出一些 API 请求。相同的结构适用于我，但不适用；

    async.waterfall([
       function (callback) {
           callback(null, latitude, longitude, callback);
       },
       getGeoNames,   
   ],
   function (err, result) {
      console.log("ok");
   })

这里是函数 getGeoNames，错误

function getGeoNames(latitude, longitude, callback) {
    var countryKey = 'country';
    var stateKey = 'administrative_area_level_1';

    var url = "http://maps.googleapis.com/maps/api/geocode/json?latlng="+latitude+","+longitude;


    request({
        url: url,
        json: true
    }, function (error, response, body) {

            var adresses = body.results[0].address_components;
            var geo = {};
            for (var i = 0, len = adresses.length; i < len; i++) {
                var adress = adresses[i];
                //console.log(adress);
                if ( adress.types[0] == countryKey ) {
                    geo.country = adress.long_name;
                    if (geo.state !== undefined) break;
                }
                else if ( adress.types[0] == stateKey ) {
                    geo.state = adress.long_name;
                    if (geo.country !== undefined) break;
                }
            };
            return callback(null, geo); // ERROR HERE <-----------------
    })
}

可以请求函数运行 callback() 函数，所以它之前是运行ned 的？我试过没有“return”，但它是一样的。

        if (fn === null) throw new Error("Callback was already called.");
                         ^
Error: Callback was already called. at c:\Users\Serega\node_modules\async\dist\async.js:803:36 at Request._callback (c:\Users\Serega\WebstormProjects\untitled1\server.js:174:20) at Request.self.callback (c:\Users\Serega\node_modules\request\request.js:200:22) at emitTwo (events.js:87:13) at Request.emit (events.js:172:7) at Request. (c:\Users\Serega\node_modules\request\request.js:1067:10) at emitOne (events.js:82:20) at Request.emit (events.js:169:7) at IncomingMessage. (c:\Users\Serega\node_modules\request\request.js:988:12) at emitNone (events.js:72:20)

Process finished with exit code 1

PS: 其他瀑布函数可以根据我的要求使用。

感谢您的帮助！

Answer 1

错误在这里。

callback(null, latitude, longitude, callback);

您不应将回调作为参数传递。

Node.js "Callback is already called"。但是没有任何其他回调

Node.js "Callback is already called". But there are no any other callbacks

javascript

request

asynccallback

node.js