I am using mongoose and node and I am trying to paginate data from sub-documents. I am able to limit subdocuments, but not skip them.
The versions I am using are:
Mongo 3.0.0
Node 0.10.33
Mongoose 3.9.7
The Data
[{
"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")
}
]
}]
The Code
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);
});
The Result The above code DOES limit the number of "body" sub-documents to 2, but doesn't skip any.
The code above returns this:
{
"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")
}
]
}
But it should return this:
{
"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")
}
]
}
The solution that I found was to use aggregate and specify the name of the subdocument with $unwind.
http://docs.mongodb.org/manual/reference/operator/aggregation/
feed.aggregate([
{'$match':{_id:id('550234d3d06039d507d238d8')}},
{'$unwind':'$body'},
{'$skip':2},
{'$limit':2},
], function(err, result){
if(err){return(res.send(500, err))}
res.send(result);
});
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