如何按升序对Firebase密钥进行排序? [英] How to sort Firebase Keys in ascending order?

问题描述

我的Firebase数据库中有一个产品列表.我的SKU看起来像这样 c08p10 .但是问题在于，百乘积显示在第十乘积之后.

I have a list of products in my Firebase Database. My SKU looks like this c08p10. But the problem is that Hundred product is shown after the tenth product.

请参阅屏幕截图以了解混乱的产品订单.

Please refer the screenshot for the jumbled product order.

我可以理解，产品按字母顺序排列.但是如何按以下顺序显示产品

I can understand that the products are arranging alphabetically. But how can i display the products in the below order

c08p10
c08p11
c08p12

注意

我可以在列表"视图或回收者"视图中填充数据.但是产品按Firebase DB顺序排列.如果我尝试颠倒顺序.它给出了以下结构.

I can populate the data in a List view or recycler View. But the products are arranged in the firebase DB order. If I try to reverse the order. It gives the below structure.

c08p118
c08p117
c08p116

推荐答案

Firebase密钥是字符串.当您订购字符串数据时，将按字典顺序对其进行排序.

Firebase keys are strings. And when you order string data, it is ordered lexicographically.

所以对于数字，这是正常的顺序:

So for numbers, this is the normal order:

• 1
• 9
• 10
• 11

但是对于字符串，这是正常的顺序:

But for strings, this is the normal order:

• "1"
• "11"
• "19"
• "9"

Firebase(大多数其他数据库中也没有)没有操作员可以更改此行为.相反，您将必须修改数据以获得所需的行为.因此:按字典顺序排序时，请按照您需要的顺序存储值.对于数字，您可以通过用零填充数字来实现:

There is no operator in Firebase (nor in most other databases) to change this behavior. Instead, you will have to modify the data to get the behavior you want. So: store values that are in the order you need them when sorted lexicographically. For numbers you can accomplish that by padding them with zeroes:

• "001"
• "009"
• "011"
• "019"

或者您的情况是 c09p010 等

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