Mongoose/Mongodb:从填充的查询数据中排除字段

Question

我在MEAN环境中使用以下mongoose查询来查找和输出特定作者及其相应的书籍.

Author
.findOne({personcode: code})
.select('-_id')
.select('-__v')
.populate('bookids') //referencing to book documents in another collection (->array of bookids)
.select('-_id') //this doens't affect the data coming from the bookids-documents
.select('-__v') //this doens't affect the data coming from the bookids-documents
.exec(function (err, data) {
   //foo
});

我还想从来自外部文档的填充数据中排除"_id"和"__v"字段.怎么能实现呢？

Answer 1

第二个参数populate是字段选择字符串,因此您可以这样做:

Author
  .findOne({personcode: code})
  .select('-_id -__v')
  .populate('bookids', '-_id -__v')
  .exec(function (err, data) {
    //foo
});

请注意,您应该将字段选择组合为单个字符串.

Answer 2

单独排除

User.findOne({_id: userId}).select("-password")

排除使用架构

var userSchema = mongoose.Schema({
  email: {
    type: String,
    required: true,
    unique: true,
  },
  password: {
    type: String,
    required: true,
    select: false,
  },
});

或者这也行

db.collection.find({},{"field_req" : 1,"field_exclude":0});

Answer 3

感谢 JohnnyHK，对于对象参数，这有效：

Entity.populate({
    path: 'bookids',

    // some other properties
    match: {
        active: true
    },
    // some other properties

    select: '-_id -__v' // <-- this is the way
}).then(...) // etc