MongoDB - 在 ObjectId 上聚合 $match

Question

我有一个看起来像这样的模式:

var mongoose = require('mongoose');

module.exports = mongoose.model('Owner',{
    username: String,
    blocks: {type:mongoose.Schema.Types.ObjectId, ref: 'Block'},
});

我正在尝试运行查询以查看 Owner 是否引用了 Block 的 ID。所有者有一组 ObjectId。当我运行 db.owners.aggregate({$match: {username: 'example'}},{$unwind: "$blocks"},{$project: { _id : 1,blocks: 1}})它返回:

{ "_id" : ObjectId("550d9dc64d9dc3d026fadfc7"), "blocks" : ObjectId("550dc117dc9605ab27070af7") }
{ "_id" : ObjectId("550d9dc64d9dc3d026fadfc7"), "blocks" : ObjectId("550dc123dc9605ab27070af8") }
{ "_id" : ObjectId("550d9dc64d9dc3d026fadfc7"), "blocks" : ObjectId("550dc12edc9605ab27070af9") }
{ "_id" : ObjectId("550d9dc64d9dc3d026fadfc7"), "blocks" : ObjectId("550dc157dc9605ab27070afa") }

如何匹配区 block id？我试过了 db.publishers.aggregate({$match: {username: 'example'}},{$unwind: "$blocks"},{$project: { _id : 1,blocks: 1}},{$match : {"blocks._id" : '550dc157dc9605ab27070afa'}})但这不起作用。

Answer 1

我认为您不需要聚合，您可以使用简单的 find() 或 findOne() 查询:

var Mongoose = require('mongoose');
var ObjectId = Mongoose.Types.ObjectId;

Owner.findOne({ username: 'example', blocks: new ObjectId('550dc157dc9605ab27070afa') }, function (err, owner) {
   ...
});