如何使用 MongoMapper 查询 distinct?我的查询是:
subscribedToThread = Comment.where(:subscribe_thread => 1).all
但这将返回许多具有相同user_id 的对象.我只需要返回一个不同的 user_id.这可能吗?
我认为你需要下拉到 ruby 驱动程序才能做到这一点，因为我认为你不能用 MongoMapper 本身做到这一点:
>
subscribedToThread = Comment.collection.distinct("user_id", {:subscribe_thread => 1})在模型上调用集合方法会返回由 Ruby 驱动程序直接提供的集合，因此您可以使用以下语法发出不同的查询:
collection.distinct(key, query = nil)
您可以在此处
How do I query distinct with MongoMapper? My query is:
subscribedToThread = Comment.where(:subscribe_thread => 1).all
But this will return many objects with the same user_id. I need to return just a distinct user_id. Is this possible?
I think you will need to drop down to the ruby driver in order to do this as I don't think you can do this with MongoMapper itself:
subscribedToThread = Comment.collection.distinct("user_id", {:subscribe_thread => 1})
Calling the collection method on a model returns the collection as would be provided by the Ruby driver directly so you can issue a distinct query using the syntax below:
collection.distinct(key, query = nil)
You can read more about it here
这篇关于使用 MongoMapper 查询不同的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！