如何在 Mongoose 中查询不同的值？

发布于 2024-11-08 15:29:52 字数 775 浏览 0 评论 0原文

我有一个问题，我希望能够获取集合中的所有唯一城市，我的代码如下所示：

var mongoose = require("mongoose"),
Schema = mongoose.Schema;

var PersonSchema = new Schema({
    name: String,
    born_in_city: String
});
var Person = mongoose.model('Person', PersonSchema);

在本机 MongoDb 中，我可以执行 db.person.distinct("born_in_city")，但似乎没有与 Mongoose 等效的东西。是我自己迭代所有文档来执行此操作的唯一选择，还是有更好的解决方案？

在尝试按照回答者的建议使用底层 node-mongodb-native 时，我尝试这样做：

mongoose.connection.db.collections(function(err, collections){
  collections[0].distinct('born_in_city', function( err, results ){
    console.log( err, results );
  });
});

但是 结果 是空的，并且没有错误。我还希望能够按名称仅获取所需的集合，而不必过滤 collections 返回的内容（如果可能的话）。

原文

I have a problem where I want to be able to get all the unique cities for a collection, and my code looks something like this:

var mongoose = require("mongoose"),
Schema = mongoose.Schema;

var PersonSchema = new Schema({
    name: String,
    born_in_city: String
});
var Person = mongoose.model('Person', PersonSchema);

In native MongoDb I could just do db.person.distinct("born_in_city"), but there doesn't seem to be anything equivalent for Mongoose. Is the only option to iterate over all of the documents myself to do this, or is there a better solution?

In an attempt to use the underlying node-mongodb-native as suggested by the answerer I attempted to do this:

mongoose.connection.db.collections(function(err, collections){
  collections[0].distinct('born_in_city', function( err, results ){
    console.log( err, results );
  });
});

However the results is empty and there's no error. I would also prefer to be able to fetch only the needed collection by name rather than have to filter what collections return if at all possible.

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冬天旳寂寞 2024-11-15 15:29:52

只是提供 Mongoose 3.x 的更新：

MyModel.find().distinct('_id', function(error, ids) {
    // ids is an array of all ObjectIds
});

Just to give an update for Mongoose 3.x:

MyModel.find().distinct('_id', function(error, ids) {
    // ids is an array of all ObjectIds
});

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我不咬妳我踢妳 2024-11-15 15:29:52

在我的程序中，这段代码有效。

Person.collection.distinct("born_in_city", function(error, results){
  console.log(results);
});

经过
节点.js v0.4.7,
猫鼬1.3.3

In my program, this code works.

Person.collection.distinct("born_in_city", function(error, results){
  console.log(results);
});

by
node.js v0.4.7,
mongoose 1.3.3

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濫情▎り 2024-11-15 15:29:52

const findBornCity = async() => {
    const bornCity = await Person.find().distinct("born_in_city")
    return bornCity
}

const findBornCity = async() => {
    const bornCity = await Person.find().distinct("born_in_city")
    return bornCity
}

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凉风有信 2024-11-15 15:29:52

我通读了源代码，node-mongodb-native 驱动程序为该类提供了动力。那么在连接对象上。因此，在完成 mongoose.connect(mongodb://) 之后，您可以尝试一下。

if(mongoose.connections.length > 0) {
  var nativeconn = mongoose.connections[0].conn;
  nativeconn.person.distinct('born_in_city', function(error, results){

  });
}

I read through the source code and the node-mongodb-native driver is what powers the class. So on the connection object. So after you have done mongoose.connect(mongodb://), you can give this a shot.

if(mongoose.connections.length > 0) {
  var nativeconn = mongoose.connections[0].conn;
  nativeconn.person.distinct('born_in_city', function(error, results){

  });
}

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~没有更多了~