Mongo DB按字段名称查找任何值 [英] Mongo DB find by field name with any value

问题描述

我正在尝试查找所有具有此字段的文档，它包含的确切值无关紧要；我只对它的存在感兴趣.

I am trying to find all documents that have this field, it doesn't matter what exact value it contains; I am only interested in the existence of it.

这里是一个例子:

{  
   "payload":{  
      "products":{  
         ...
      },
      "discount":{  
         "type":"1%",
         "value":"1",
         "name":"New Year Discount 1%"
      }
   }
}

我需要定位任何具有名称为discount的字段的文档.如何编写查询以获取此类文档?

I need to target any document that has a field with the name discount. How can I write a query to get such documents?

推荐答案

有一个 $ exists 运算符:

db.collectionName.find({"payload.discount": {$exists: true}})

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