I am trying to set up a blog, where each post contains multiple paragraphs. I would simply like to count the number of paragraphs in a particular post. In the "Blog" collection, my documents (=posts) are as follow :
{ id : String
title : String
paragraphs : [ { position: Int, body: String } ] }
I would like a function returning an Integer. Maybe something close to :
var NumberParagraphs = Blog.find( {id: id} ).paragraphs.length
(obviously this doesn't work ! ) ... Could you advise me which way to investigate? while searching the net, I am getting confused between use case for .count()
, $size
, or .aggregate
The .find()
method does not return a single document. So you either want to loop those documents as an array:
Blog.find({ id: id }).fetch().forEach(function(doc) {
var NumParagraphs = doc.paragraphs.length;
// Then do something useful
})
Or just .findOne()
for a single document:
var doc = Blog.findOne({ id: id });
var NumParagraphs = doc.paragraphs.length;
The same principles apply to the raw methods for MongoDB, not just meteor.
And an example using the aggregate method and $size, in case you were wondering:
var numParagraphs = Blog.aggregate([
{
$match : {
"_id" : id
}
},
{
$project : {
"pCount" : {$size : '$paragraphs'}
}
}
]).pCount;
You should do
Blog.findOne({_id:id}).paragraphs.length
Thanks
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