在Firestore中使用DocumentReference和仅使用id有什么区别？

本文介绍了在Firestore中使用DocumentReference和仅使用id有什么区别？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 在Firestore中，您可以创建数据类型为Reference的对象。但这只是说文件的路径。使用这个和使用id作为字符串字段有什么区别？任何优点/缺点？

解决方案

参考文献一个文档，而一个简单的字符串ID没有上下文。当然，您可以将路径存储为一个字符串，但为了方便（在自定义对象）将整个 Reference引用对象存储是非常有用的。

引用的排序顺序也不同于 String 的排序顺序。从支持的数据类型文档：

• 引用排序顺序：按路径元素（集合，文档ID，集合，文档ID ...） b $ b
• 文本字符串排序顺序：UTF-8编码的字节顺序

您还可以在参考对象进行比较query-data / queriesrel =nofollow noreferrer>编写查询。 $ b

例如： document（1）; var query = db.collection（test）。orderBy（ref）。where（ref，>，reference）;

In Firestore you can create objects with data type Reference. But this is just the path to said document. What's the difference between using this and just using the id as a String field? Any advantages/disadvantages?

解决方案

A Reference contains the entire path to a document, whereas a simple string ID has no context. Granted, you could just store the path as a string instead, but for convenience (and ease of use in custom objects) it can be useful to have the entire Reference object stored.

The sort order of a Reference is also different to that of a String. From the Supported Data Types documentation:

• Reference sort order: By path elements (collection, document ID, collection, document ID...)
• Text string sort order: UTF-8 encoded byte order

This means that you can also filter on a Reference object in the database by comparing it to another when writing queries.

For example:

var reference = db.collection("test").document("1"); var query = db.collection("test").orderBy("ref").where("ref", ">", reference);