您的文档以斜体显示的原因是它当前不存在。在 Cloud Firestore 中，子集合可以存在而无需其父文档也存在。
如 Firebase 控制台所述，不存在的文档不会出现在客户端 SDK 的查询或快照中。
此文档不存在，不会出现在查询或快照中
如果您希望能够获得您的入境日期，您需要创建文档（可以为空）。
firebase.firestore()
.collection('WaterCanData')
.doc(EntryDate)
.set({}); // an empty document
要在创建文档的同时为其子集合中的条目创建文档，您可以像这样使用批量写入：
const db = firebase.firestore();
const batch = db.batch();
// get references to the relevant locations
const entryDateRef = db
.collection('WaterCanData')
.doc(EntryDate);
const customerRef = entryDateRef
.collection('Entries')
.doc(values.customerName);
// queue the data to write
batch.set(entryDateRef, {});
batch.set(customerRef, {
CustomerName: values.customerName,
CansOut: values.cansOut,
JarsOut: values.jarsOut,
EmptyCansIn: values.emptyCansIn,
JarsIn: values.jarsIn,
Bottles: values.bottles,
Ice: values.ice
})
// make changes to database
batch.commit()
.then(() => {
console.log('Entry added!!!!!!!!!');
});
这将允许您使用以下内容列出数据库中的所有条目日期：
firebase.firestore().collection('WaterCanData')
.get()
.then((querySnapshot) => {
querySnapshot.forEach(doc => {
const entryDate = doc.id;
// const customerEntriesRef = doc.ref.collection('Entries');
console.log('Entry date found: ' + entryDate);
}
});
如果（例如）您还想知道有多少条目链接到给定日期，您还需要查询每个子集合（这里的代码有点混乱）。
firebase.firestore().collection('WaterCanData')
.get()
.then((querySnapshot) => {
const fetchSizePromises = [];
// for each entry date, get the size of it's "Entries" subcollection
querySnapshot.forEach(doc => {
const entryDate = doc.id;
const customerEntriesRef = doc.ref.collection('Entries');
// if this get() fails, just store the error rather than throw it.
const thisEntrySizePromise = customerEntriesRef.get()
.then(
(entriesQuerySnapshot) => {
return { date: entryDate, size: entriesQuerySnapshot.size }
},
(error) => {
return { date: entryDate, size: -1, error }
}
);
// add this promise to the queue
fetchSizePromises.push(thisEntrySizePromise)
}
// wait for all fetch operations and return their results
return Promise.all(fetchSizePromises);
})
.then((entryInfoResults) => {
// for each entry, log the result
entryInfoResults.forEach((entryInfo) => {
if (entryInfo.error) {
// this entry failed
console.log(`${entryInfo.date} has an unknown number of customers in its Entries subcollection due to an error`, entryInfo.error);
} else {
// got size successfully
console.log(`${entryInfo.date} has ${entryInfo.size} customers in its Entries subcollection`);
}
}
});