資料庫 (輸入階段)

資料庫 (輸入階段)

說明

傳回資料庫中不同集合和巢狀層級的所有文件。

範例

網頁

// Count all documents in the database
const results = await execute(db.pipeline()
  .database()
  .aggregate(countAll().as("total"))
  );
test.firestore.js

Swift

// Count all documents in the database
let results = try await db.pipeline()
  .database()
  .aggregate([CountAll().as("total")])
  .execute()
PipelineSnippets.swift

Kotlin
Android

// Count all documents in the database
val results = db.pipeline()
    .database()
    .aggregate(AggregateFunction.countAll().alias("total"))
    .execute()
DocSnippets.kt

Java
Android

      // Count all documents in the database
Task<Pipeline.Snapshot> results = db.pipeline()
    .database()
    .aggregate(AggregateFunction.countAll().alias("total"))
    .execute();
DocSnippets.java
    

Python

from google.cloud.firestore_v1.pipeline_expressions import Count

# Count all documents in the database
results = client.pipeline().database().aggregate(Count().as_("total")).execute()
firestore_pipelines.py

Java

// Count all documents in the database
Pipeline.Snapshot results =
    firestore.pipeline().database().aggregate(countAll().as("total")).execute().get();
PipelineSnippets.java

行為

如要使用 database(...) 階段，該階段必須是管道中的第一個階段。

從 database(...) 階段傳回的文件順序不穩定，因此不建議依此排序。後續的 sort(...) 階段可用於取得確定性排序。

舉例來說，下列文件：

Node.js

await db.collection("cities").doc("SF").set({name: "San Francsico", state: "California", population: 800000});
await db.collection("states").doc("CA").set({name: "California", population: 39000000});
await db.collection("countries").doc("USA").set({name: "United States of America", population: 340000000});

database(...) 階段可用於擷取資料庫中的所有文件。

Node.js

const results = await db.pipeline()
  .database()
  .sort(field("population").ascending())
  .execute();

這項查詢會產生下列文件：

  { name: "San Francsico", state: "California", population: 800000 }
  { name: "California", population: 39000000 }
  { name: "United States of America", population: 340000000 }