如何在 Cloud Firestore 文檔中列出子集合

Question

假設我將這個最小的數據庫存儲在 Cloud Firestore 中。 如何檢索subCollection1和subCollection2的名稱？

rootCollection {
    aDocument: {
        someField: { value: 1 },
        anotherField: { value: 2 }
        subCollection1: ...,
        subCollection2: ...,
    }
}

我希望能夠從aDocument中讀取 id，但是當我get()文檔時只顯示字段。

rootRef.doc('aDocument').get()
  .then(doc =>

    // only logs [ "someField", "anotherField" ], no collections
    console.log( Object.keys(doc.data()) )
  )

Answer 1

在 Node.js 中，您將使用“ListCollectionIds”方法

var firestore = require('firestore.v1beta1');

var client = firestore.v1beta1({
  // optional auth parameters.
});

// Iterate over all elements.
var formattedParent = client.anyPathPath("[PROJECT]", "[DATABASE]", "[DOCUMENT]", "[ANY_PATH]");

client.listCollectionIds({parent: formattedParent}).then(function(responses) {
    var resources = responses[0];
    for (var i = 0; i < resources.length; ++i) {
        // doThingsWith(resources[i])
    }
})
.catch(function(err) {
    console.error(err);
});

客戶端 SDK（Web、iOS、Android）目前不支持此功能。

Answer 2

似乎他們在 Node.js 中添加了一個名為getCollections()的方法：

firestore.doc(`/myCollection/myDocument`).getCollections().then(collections => {
  for (let collection of collections) {
    console.log(`Found collection with id: ${collection.id}`);
  }
});

此示例打印出位於/myCollection/myDocument的文檔的所有子集合

Answer 3

文檔中沒有詳細說明嗎？

 /** * Delete a collection, in batches of batchSize. Note that this does * not recursively delete subcollections of documents in the collection */ function deleteCollection(db, collectionRef, batchSize) { var query = collectionRef.orderBy('__name__').limit(batchSize); return new Promise(function(resolve, reject) { deleteQueryBatch(db, query, batchSize, resolve, reject); }); } function deleteQueryBatch(db, query, batchSize, resolve, reject) { query.get() .then((snapshot) => { // When there are no documents left, we are done if (snapshot.size == 0) { return 0; } // Delete documents in a batch var batch = db.batch(); snapshot.docs.forEach(function(doc) { batch.delete(doc.ref); }); return batch.commit().then(function() { return snapshot.size; }); }).then(function(numDeleted) { if (numDeleted <= batchSize) { resolve(); return; } // Recurse on the next process tick, to avoid // exploding the stack. process.nextTick(function() { deleteQueryBatch(db, query, batchSize, resolve, reject); }); }) .catch(reject); }

Answer 4

這個答案在文檔中

遺憾的是，文檔並不清楚您導入的內容。

根據文檔，我的代碼最終看起來像這樣：

import admin, { firestore } from 'firebase-admin'

let collections: string[] = null
const adminRef: firestore.DocumentReference<any> = admin.firestore().doc(path)
const collectionRefs: firestore.CollectionReference[] = await adminRef.listCollections()
collections = collectionRefs.map((collectionRef: firestore.CollectionReference) => collectionRef.id)

這當然是 Node.js 服務器端代碼。 根據文檔，這不能在客戶端上完成。