排序Firestore文件 [英] Sorting Firestore Documents

问题描述

有什么可能的方法可以根据特定字段值上的数字对集合的Cloud Firestore文档进行排序.例如，在 ids 集合中有文档，在每个文档中都有一个名为 idNumber 的字段.该idNumber的值为0，然后在下一个文档中为1，然后为2，以此类推.

Is there any possible way I can order the Cloud Firestore documents of a collection based on a number at a value of a specific field. For example in the collection ids there are documents and in each one there is a field called idNumber. The value of that idNumber is 0 then in the next document is 1 then 2 etc. Is it possible?

提前谢谢！

推荐答案

有可能吗?

是的！要通过特定的数字属性对集合中的文档进行排序，请使用以下查询:

Yes it is! To order the documents within a collection by a specific numeric property, please use the following query:

FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
CollectionReference idsRef = rootRef.collection("ids");
Query query = idsRef.orderBy("idNumber", Query.Direction.ASCENDING);

此查询将根据 idNumber 属性的升序对文档进行排序.如果您想要相反的顺序，只需将方向更改为 DESCENDING .就是这样！

This query will order your documents according to the idNumber property ascending. If you want a reverse order just change the direction to DESCENDING. That's it!

根据Query的

According to the official documentation of Query's orderBy(String field) method:

创建并返回一个新的查询，该查询还会按指定的字段进行排序.

Creates and returns a new Query that's additionally sorted by the specified field.

并根据Query的

And according to Query's orderBy(String field, Query.Direction direction) method:

创建并返回一个新的查询，该查询还会根据指定的字段进行排序，可以选择以降序而不是升序进行排序.

Creates and returns a new Query that's additionally sorted by the specified field, optionally in descending order instead of ascending.

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