我有一个角度函数来从一个 firestore 集合中获取产品，然后循环该查询的结果以从另一个集合中查找价格。我怎样才能等到 forEach 的价格完成后再从外部承诺和外部函数本身返回？返回的结果包含一个产品数组，但每个产品的价格数组为空。 const products = await this.billingService.getProducts();async getProducts() { let result = []; let product = {}; return this.db.collection( 'products', ref => { ref let query: Query = ref; return query.where('active', '==', true) }) .ref .get() .then(function (querySnapshot) { querySnapshot.forEach(async function (doc) { product = doc.data(); product['prices'] = []; await doc.ref .collection('prices') .orderBy('unit_amount') .get() .then(function (docs) { // Prices dropdown docs.forEach(function (doc) { const priceId = doc.id; const priceData = doc.data(); product['prices'].push(priceData); }); }); }); result.push(product); return result; }); }我也尝试过这种方法，但不知道如何访问结果await this.billingService.getProducts().then(results =>getProducts() { const dbRef = this.db.collection( 'products', ref => { ref let query: Query = ref; return query.where('active', '==', true) }); const dbPromise = dbRef.ref.get(); return dbPromise .then(function(querySnapshot) { let results = []; let product = {}; querySnapshot.forEach(function(doc) { let docRef = doc.ref .collection('prices') .orderBy('unit_amount') results.push(docRef.get()) }); return Promise.all(results) }) .catch(function(error) { console.log("Error getting documents: ", error); }); }
3 回答
不负相思意
TA贡献1777条经验 获得超10个赞
让 getProducts() 函数成为一个承诺。因此，只有当您解决它（或拒绝它）时它才会返回。
getProducts() {
return new Promise((resolve,reject)=> {
let result = [];
let product = {};
this.db.collection(
'products',
ref => { ref
let query: Query = ref;
return query.where('active', '==', true)
})
.ref
.get()
.then(function (querySnapshot) {
querySnapshot.forEach(async function (doc) {
product = doc.data();
product['prices'] = [];
doc.ref
.collection('prices')
.orderBy('unit_amount')
.get()
.then(function (docs) {
// Prices dropdown
docs.forEach(function (doc) {
const priceId = doc.id;
const priceData = doc.data();
product['prices'].push(priceData);
});
resolve(result);// returns when it reaches here
});
});
result.push(product);
});
})
}
然后你可以使用 then 或await 来调用promise
this.billingService.getProducts().then( res => {
const products = res;
})
使用等待
const products = await this.billingService.getProducts();
守着一只汪
TA贡献1872条经验 获得超3个赞
此版本的代码有效：
getProducts(): Promise<any> {
return new Promise((resolve,reject)=> {
let result = [];
let product = {};
this.db.collection(
'products',
ref => { ref
let query: Query = ref;
return query.where('active', '==', true)
})
.ref
.get()
.then(async function (querySnapshot:firebase.firestore.QuerySnapshot) {
for(const doc of querySnapshot.docs) {
const priceSnap = await doc.ref
.collection('prices')
.orderBy('unit_amount')
.get()
product = doc.data();
product['prices'] = [];
// Prices dropdown
for(const doc of priceSnap.docs) {
const priceId = doc.id;
let priceData = doc.data();
priceData['price_id'] = priceId;
product['prices'].push(priceData);
resolve(result);// returns when it reaches here
};
result.push(product);
};
});
})
}
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