如何通过_id检索文档? [英] How can I retrieve a document by _id?

问题描述

当我有对象ID时，我正在尝试检索文档-但是，该查询无法正常工作.

I'm trying to retrieve a document when I have an object id - however, the query does not work.

@collection = @db.collection('Mylist')
@result = @collection.find({"_id" => params[:id]})

我尝试过查询的变体-它总是产生空的-但是，当我尝试对如下所示的集合进行查询时，那会起作用.

I've tried variations of the query - it always yields empty - however when I try a query on the collection such as below, that would work.

@result = @collection.find({"Exist" => "True"}) 

为什么?奇怪的是，复杂的查询有效，但是通过_id进行的简单查询却什么也没有返回.

Why? It is strange that complex queries work but a simple query by _id returns nothing.

如果可能的话，我不想使用MongoMapper.

If possible, I don't want to use MongoMapper.

谢谢

推荐答案

找到它-您需要像这样包装它-

Found it - you need to wrap it like this -

find({"_id" => Mongo::ObjectId(params[:id])}) 

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