javascript - 无法 “skip” Mongoose 子文档

我正在使用 Mongoose 和节点，并且试图从子文档中分页数据。我可以限制子文档，但不能跳过它们。

我使用的版本是:

蒙戈3.0.0

节点0.10.33

Mongoose 3.9.7

数据

[{
    "name" : "Ranger Table",
    "_id" : ObjectId("550234d3d06039d507d238d8"),
    "body" : [
        {
            "name" : "Jason",
            "colour" : "Red",
            "animal" : "T-rex",
            "_id" : ObjectId("550234d3d06039d507d238de")
        },
        {
            "name" : "Billy",
            "colour" : "Blue",
            "animal" : "Triceratops",
            "_id" : ObjectId("550234d3d06039d507d238dd")
        },
        {
            "name" : "Zach",
            "colour" : "Black",
            "animal" : "Mastadon",
            "_id" : ObjectId("550234d3d06039d507d238dc")

        },
        {
            "name" : "Tommy",
            "colour" : "Green",
            "animal" : "Dragon"
            "_id" : ObjectId("550234d3d06039d507d238d9")
        }
    ]
},{
    "name" : "Bot Table",
    "_id" : ObjectId("5502d205184cd74033f64e6b"),
    "body" : [
        {
            "name" : "Optimus",
            "team" : "Autobots",
            "class" : "Leader",
            "_id" : ObjectId("550234d3d06039d507d238d9")
        },
        {
            "name" : "Bumblebee",
            "team" : "Autobots",
            "class" : "Scout",
            "_id" : ObjectId("550234d3d06039d507d238da")
        },
        {
            "name" : "Astrotrain",
            "team" : "Decepticons",
            "class" : "Transport",
            "_id" : ObjectId("550234d3d06039d507d238db")

        }
    ]
}]

代码

var BodySchema = new Schema({random: String},{strict:false});

var FeedSchema = new Schema({
  name: String,
  body:[BodySchema]
});

var feed = mongoose.model('Feed', FeedSchema);

feed.find({_id:'550234d3d06039d507d238d8'})
    .populate({
        "path":"body",
        "options":{
            limit:2, //This works fine
            skip:2  //This doesn't work
        }
    })
    .exec(function(err, result){

        if(err){return(res.send(500, err))}

        res.send(result);
    });

结果
上面的代码确实将“主体”子文档的数量限制为2，但是不跳过任何子文档。

上面的代码返回以下内容:

{
    "name" : "Ranger Table",
    "_id" : ObjectId("550234d3d06039d507d238d8"),
    "body" : [
        {
            "name" : "Jason",
            "colour" : "Red",
            "animal" : "T-rex",
            "_id" : ObjectId("550234d3d06039d507d238de")
        },
        {
            "name" : "Billy",
            "colour" : "Blue",
            "animal" : "Triceratops",
            "_id" : ObjectId("550234d3d06039d507d238dd")
        }
    ]
}

但是它应该返回以下内容:

{
    "name" : "Ranger Table",
    "_id" : ObjectId("550234d3d06039d507d238d8"),
    "body" : [
        {
            "name" : "Zach",
            "colour" : "Black",
            "animal" : "Mastadon",
            "_id" : ObjectId("550234d3d06039d507d238dc")

        },
        {
            "name" : "Tommy",
            "colour" : "Green",
            "animal" : "Dragon"
            "_id" : ObjectId("550234d3d06039d507d238d9")
        }
    ]
}

最佳答案

我发现的解决方案是使用聚合并使用$ unwind指定子文档的名称。

http://docs.mongodb.org/manual/reference/operator/aggregation/

feed.aggregate([
    {'$match':{_id:id('550234d3d06039d507d238d8')}},
    {'$unwind':'$body'},
    {'$skip':2},
    {'$limit':2},
], function(err, result){

    if(err){return(res.send(500, err))}

    res.send(result);

});

关于javascript - 无法 “skip” Mongoose 子文档，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/29032727/