Union

說明

將其他管道的文件與目前管道的文件合併。

範例

Node.js
  const results = await db.pipeline()
    .collection("cities/SF/restaurants")
    .where(eq("type", "chinese"))
    .union(db.pipeline()
      .collection("cities/NYC/restaurants")
      .where(eq("type", "italian")))
    .where(gte("rating", 4.5))
    .execute();

Web

const results = await execute(db.pipeline()
  .collection("cities/SF/restaurants")
  .where(field("type").equal("Chinese"))
  .union(db.pipeline()
    .collection("cities/NY/restaurants")
    .where(field("type").equal("Italian")))
  .where(field("rating").greaterThanOrEqual(4.5))
  .sort(field("__name__").descending())
);
Swift
let results = try await db.pipeline()
  .collection("cities/SF/restaurants")
  .where(Field("type").equal("Chinese"))
  .union(with: db.pipeline()
    .collection("cities/NY/restaurants")
    .where(Field("type").equal("Italian")))
  .where(Field("rating").greaterThanOrEqual(4.5))
  .sort([Field("__name__").descending()])
  .execute()

Kotlin

val results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute()

Java

Task<Pipeline.Snapshot> results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute();
Python
from google.cloud.firestore_v1.pipeline_expressions import Field

results = (
    client.pipeline()
    .collection("cities/SF/restaurants")
    .where(Field.of("type").equal("Chinese"))
    .union(
        client.pipeline()
        .collection("cities/NY/restaurants")
        .where(Field.of("type").equal("Italian"))
    )
    .where(Field.of("rating").greater_than_or_equal(4.5))
    .sort(Field.of("__name__").descending())
    .execute()
)
Java
Pipeline.Snapshot results =
    firestore
        .pipeline()
        .collection("cities/SF/restaurants")
        .where(field("type").equal("Chinese"))
        .union(
            firestore
                .pipeline()
                .collection("cities/NY/restaurants")
                .where(field("type").equal("Italian")))
        .where(field("rating").greaterThanOrEqual(4.5))
        .sort(descending(field("__name__")))
        .execute()
        .get();
Go
snapshot := client.Pipeline().
	Collection("cities/SF/restaurants").
	Where(firestore.FieldOf("type").Equal("Chinese")).
	Union(
		client.Pipeline().
			Collection("cities/NY/restaurants").
			Where(firestore.FieldOf("type").Equal("Italian")),
	).
	Where(firestore.FieldOf("rating").GreaterThanOrEqual(4.5)).
	Sort(firestore.Orders(firestore.Descending(firestore.FieldOf("__name__")))).
	Execute(ctx)

行為

這個階段會平行執行多個管道，並將結果串連在一起。

結果順序不確定

兩個管道之間合併結果的順序不確定。任何感知順序都不穩定，不應依此為準。 如果需要穩定的順序，可以新增後續的 sort(...) 階段。

Node.js
  const results = await db.pipeline()
    .collection("cities/SF/restaurants")
    .where(eq("type", "chinese"))
    .union(db.pipeline()
      .collection("cities/NYC/restaurants")
      .where(eq("type", "italian")))
    .where(gte("rating", 4.5))
    .sort(Field.of("__name__"))
    .execute();

Kotlin

val results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute()

Java

Task<Pipeline.Snapshot> results = db.pipeline()
    .collection("cities/SF/restaurants")
    .where(field("type").equal("Chinese"))
    .union(db.pipeline()
        .collection("cities/NY/restaurants")
        .where(field("type").equal("Italian")))
    .where(field("rating").greaterThanOrEqual(4.5))
    .sort(field("__name__").descending())
    .execute();
Python
from google.cloud.firestore_v1.pipeline_expressions import Field

results = (
    client.pipeline()
    .collection("cities/SF/restaurants")
    .where(Field.of("type").equal("Chinese"))
    .union(
        client.pipeline()
        .collection("cities/NY/restaurants")
        .where(Field.of("type").equal("Italian"))
    )
    .where(Field.of("rating").greater_than_or_equal(4.5))
    .sort(Field.of("__name__").descending())
    .execute()
)
Java
Pipeline.Snapshot results =
    firestore
        .pipeline()
        .collection("cities/SF/restaurants")
        .where(field("type").equal("Chinese"))
        .union(
            firestore
                .pipeline()
                .collection("cities/NY/restaurants")
                .where(field("type").equal("Italian")))
        .where(field("rating").greaterThanOrEqual(4.5))
        .sort(descending(field("__name__")))
        .execute()
        .get();
Go
snapshot := client.Pipeline().
	Collection("cities/SF/restaurants").
	Where(firestore.FieldOf("type").Equal("Chinese")).
	Union(
		client.Pipeline().
			Collection("cities/NY/restaurants").
			Where(firestore.FieldOf("type").Equal("Italian")),
	).
	Where(firestore.FieldOf("rating").GreaterThanOrEqual(4.5)).
	Sort(firestore.Orders(firestore.Descending(firestore.FieldOf("__name__")))).
	Execute(ctx)

重複結果

union(...) 階段不會重複資料。如果需要移除重複結果，可以新增後續的distinct(...)或aggregate(...)階段。