Firebase匹配子字符串 [英] Firebase matching substring

问题描述

我上面有JSON结构

I have the JSON structure above

我想获取其ID以"123"结尾的车辆列表

I want to get the list of vehicles where their ids ends with "123"

我曾经尝试使用Query.endAt()方法，但是我不确定我是在正确使用它还是不应该提供所需的输出

I had tried to use Query.endAt() method but i'm not sure if i'm using it right or it shouldn't give the required output

Query vehiclesRef;
vehiclesRef = db.getReference("vehicles").orderByKey().endAt("\uf8ff123");

推荐答案

Firebase数据库查询只能执行前缀匹配，因此字符串以特定字符串开头或以字符串范围开头.无法查询具有特定值的字符串 ending 或以某个值范围结尾的字符串.

Firebase Database queries can only perform prefix matches, so strings starting with a specific string or starting with a range of string. It is not possible to query for strings ending with a specific value, nor those ending with a range of values.

如果您真的想在Firebase中执行此操作，请考虑将反向字符串也存储在数据库中:

If you really want to do this within Firebase, consider also storing the reversed strings in the database:

"321_1_0"
"321_3_0"
"654_52_0"

然后您可以使用

321查询以 321 开头的字符串

Then you can query for strings starting with 321 with

vehiclesQuery = db.getReference("vehicles").orderByKey().startAt("321").endAt("321\uf8ff");

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