检查request.resource.data是否是Firebase Firestore中的字符串列表 [英] Check if request.resource.data is a list of strings in Firebase Firestore

问题描述

如何检查Firestore规则中的字段是否为string[]类型?

我在文档中有一个tags字段，该字段应该是字符串列表，我想强制执行该操作.通常，如果我想查看该字段是否为int，我可以说request.resource.data is int，但是找不到与lists对应的字段.

谢谢！

解决方案

规则语言中没有显式类型检查(至少据我所知).因此，我能想到的最好的方法是尝试找到一种方法来区分 List (数组的类型)以及其他类型.

例如，列表具有join()方法，该方法可用于将列表中的值连接到单个字符串中.由于(据我所知)其他所有类型都没有该操作，因此此检查可以检测到数组:

allow write: if request.resource.data.categories.join(",") != "";

任何非空数组都将通过此测试，而空数组和其他类型将失败.在模拟器中，这给出了一个非常丑陋的错误消息，但是当暴露给客户端时，这转化为正常的，通用的拒绝权限".

供我将来参考:测试代码位于此处.

How do I check if a field is of type string[] in firestore rules?

I have a tags field in a document, which should be a list of strings, and I want to enforce that. Normally, I can say request.resource.data is int if I want to see if the field is an int, but I can't find an equivalent for lists.

Thanks!

解决方案

There is no explicit type check in the rules language (at least as far as I know). So the best I can come up with is trying to find a way to distinguish between a List (the type of an array), and other types.

For example, a list has a join() method, which can be used to concatenate the values from the list into a single string. Since (as far as I can see) none of the other types have that operation, this check can detect an array:

allow write: if request.resource.data.categories.join(",") != "";

Any non-empty array will pass this test, while empty arrays and other types will fail. In the simulator this gives a pretty ugly error message, but that translates to a normal, generic "permission denied" when exposed to clients.

For my own future reference: test code is here.

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