java - 如何获取 mongoDB 中数组的特定元素？

Question

我想获取数组的特定元素，并通过responsaveis.$ (daniela.morais@sofist.com.br) 但没有结果，我的语法有问题吗？

{
    "_id" : ObjectId("54fa059ce4b01b3e086c83e9"),
    "agencia" : "Abc",
    "instancia" : "dentsuaegis",
    "cliente" : "Samsung",
    "nomeCampanha" : "Serie A",
    "ativa" : true,
    "responsaveis" : [ 
        "daniela.morais@sofist.com.br", 
        "abc@sofist.com.br"
    ],
    "email" : "daniela.morais@sofist.com.br"
    }

语法1

mongoCollection.findAndModify("{'responsaveis.$' : #}", oldUser.get("email"))
                .with("{$set : {'responsaveis.$' : # }}", newUser.get("email"))
                .returnNew().as(BasicDBObject.class);

语法2

db.getCollection('validatag_campanhas').find({"responsaveis.$" : "daniela.morais@sofist.com.br"})

结果

Fetched 0 record(s) in 1ms

Answer 1

$ 位置运算符仅在 update(...) 或项目调用中使用，您不能使用它来返回数组中的位置。

正确的语法是:-

语法1

mongoCollection.findAndModify("{'responsaveis' : #}", oldUser.get("email"))
                .with("{$set : {'responsaveis.$' : # }}", newUser.get("email"))
                .returnNew().as(BasicDBObject.class);

语法2

db.getCollection('validatag_campanhas').find({"responsaveis" : "daniela.morais@sofist.com.br"})

如果只想投影特定元素，可以在投影中使用位置运算符$

{"responsaveis.$":1}

db.getCollection('validatag_campanhas').find({"responsaveis" : "daniela.morais@sofist.com.br"},{"responsaveis.$":1})