[英]Trying to resolve a promise chain from ES6 class functions
因此,我有一个名为Events的类,并且试图从服务器中调用异步函数。 我试图了解我哪里出了错/如何在另一个异步调用中解决承诺。 任何提示或技巧将不胜感激。
这是我正在调用的事件函数:
Event.prototype.getCost = function(name_of_place){
return new Promise( function(){
var placeID;
var GooglePlaces = require("node-googleplaces");
const places = new GooglePlaces(API_KEY);
const params = {
location: '40.689247,-123.102192',
radius: 1000
};
var query =
{
query: name_of_place
};
// ASYNC call
places.textSearch(query).then((res) => {
console.log("FIRST ASYNC CALL");
console.log(res.body.results[0].place_id);
placeID = res.body.results[0].place_id;
var request_place_details={
placeid : placeID
};
console.log(request_place_details);
return request_place_details;
}).then((request_place_details) => {
console.log("SECOND ASYNC CALL");
places.details(request_place_details).then((res) => {
console.log(res.body.result.price_level + " S");
var cost = res.body.result.price_level;
//trying to resolve getCost promise
//resolve(this.cost);
return cost;
}).then((cost) => {
console.log("ATTEMPT TO RESOLVE ORIGINAL");
this.cost = cost;
console.log(cost + " F");
//WANT TO RETURN THIS VALUE IN THE END
resolve(this.cost);
});
});
})};
这是我从以下位置调用的地方:
//Server is currently serving on port 8420
app.listen(8420,function startServer(){
console.log("Listening on :: " + 8420);
var Event1 = new events(7,10,'New York');
// console.log(Event1.getCost('Sushi'));
Event1.getCost('Sushi').then(res => {
console.log(res);
})
});
您的整个结构很复杂。 删除注释时,可以将代码简化为:
Event.prototype.getCost = function(name_of_place){
var GooglePlaces = require("node-googleplaces");
const places = new GooglePlaces(API_KEY);
//const params = {
// location: '40.689247,-123.102192',
// radius: 1000
//};
return places.textSearch({ query: name_of_place })
.then(res => res.body.results[0].place_id)
.then(placeID => places.details({ placeid : placeID }))
.then(res => res.body.result.price_level)
}
您没有正确声明承诺,请return new Promise( function(resolve, reject){}
然后可以像这样使用
places.details(request_place_details).then((res) => {
console.log(res.body.result.price_level + " S");
var cost = res.body.result.price_level;
// Just resolve it here.
resolve(cost);
});
// And here, res == cost.
Event1.getCost('Thai Moon').then(res=> {
console.log(res);
})
另请参阅Promise 文档 ,以供参考。
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