忽略了几个领域

假设你不希望最终填充文档的 address 字段中的字段 houseNum 和 street，请使用 populate()，如下所示，

Person.findOne({_id: req.params.id})
    .populate('address', '-houseNum -street')  // note the `-` symbol
    .exec(function(err, person) {
        // do something.
        // variable `person` contains the final populated data
    });

要么

Person.findOne({_id: req.params.id}, function(err, person) {
    // do something
    // variable `person` contains the final populated data
})
.populate('address', '-houseNum -street');  // note the `-` symbol

这将生成以下最终填充的文档，

填充文件

 {
    "_id":"123abc",
    "fname":"John",
    "mname":"Kennedy",
    "lname":"Doe",
    "address":{
        "_id":"456def",
        "city":"City of the dead",
        "state":"AB",
        "country:"PH"
    }
}