按日期字符串查询Firebase [英] Firebase query by date string

问题描述

我知道可以按照上一个问题中的时间戳查询，不过，如果日期格式如下：

  {
lambeosaurus：{
 date：2012-20-03，
length：12.5，
weight：5000 
}，
stegosaurus：{
 date：2015-25-13，
length：9，
weight：2500 
} 
} 
  
 
解决方案
  / div> 
您已将日期存储为字符串。当Firebase订单字符串使用词典排序。按照该顺序，2012-20-03出现在2012-25-01之前。
 
 
 
这就是为什么您链接到的问题（以及Firebase文档）通常将日期存储为时间戳。那些拥有关于日期的所有信息，保证以正确的顺序排列。
 
 
 
或者，您可以将日期存储为字符串。但在这种情况下，您必须确保日期格式按照字典顺序排列。对于你的示例：2012-01-25和2012-03-20。
 
 
 
所以在这种情况下，唯一的选择是将数据结构更改为原始问题（和文档）或者按照您的顺序排序的字符串格式想要。
 
I know that it's possible to query by timestamp as seen in previous question, However, what if the date is in the following format:
{
  "lambeosaurus": {
     "date" : "2012-20-03",
     "length" : 12.5,
     "weight": 5000
  },
 "stegosaurus": {
     "date" : "2015-25-13",
     "length" : 9,
     "weight" : 2500
  }
}
How would I go about and query this by date?
解决方案
You've stored your dates as strings. When Firebase order strings it uses lexicographic ordering. In that order, "2012-20-03" comes before "2012-25-01".

This is the reason why the question you linked to (and the Firebase documentation) usually store dates as timestamps. Those have all the information about the date, in a single number that is guaranteed to be ordered correctly.

Alternatively, you can store the date as a string. But in that case you have to make sure the date is in a format that will lexicographically order correctly too. For your sample that would be: "2012-01-25" and "2012-03-20".

So in this case your only option is to change the data structure to either what was in the original question (and documentation) or to a string format that orders in the order you want.

                        
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