CODEWITHSUNDEEP
mongodbmeteor
Marten Sytema
Marten Sytema

Reputation: 1926

Meteor/Mongodb find related records based on document's tags

I'm quite new to Meteor and its Mongo DB, and I'm wondering how I could find 'related documents'.

I have a collection of posts, that has tags, like this:

[{ title : 'title', tags: [{name : 'tag1'}, {name : 'tag2'}]}]

Now I want to query my database, to find posts that have an intersection on these tag set, where I want to order the results by size of the intersection descending.

How should this be encoded into a find() query, where the query is given an array of tags to check against as input?

Upvotes: 1

Views: 890

Answers (2)

Hubert OG
Hubert OG

Reputation: 19544

It's easy with this structure: 

[{
    title: 'title',
    tags: ['tag1', 'tag2'],
}]

Then you use:

Documents.find({
    tags: {$all: [ "alpha", "beta", "gamma" ]}
});

See here: http://docs.mongodb.org/manual/reference/operator/all/#op._S_all

Now, it may or may not work with complex objects as you have, I'm not sure. Try this:

Documents.find({
    tags: {$all: [{name: "alpha"}, {name: "beta"}]}
});

If you need the specified structure and the above query does not work, you're left with the $where query. It is very flexible, but not recommended as it's much slower than the others. See here:

http://docs.mongodb.org/manual/reference/operator/where/#op._S_where

 

 

EDIT: this one should do the job:

Documents.find({
    'tags.name': {$all: ["alpha", "beta"]}
});

Upvotes: 0

sohel khalifa
sohel khalifa

Reputation: 5578

You can also find simply as: 

Collection.find({"tags.name" : "tag1"})

This will give all matching documents that have 'tag1' in the tags array.

Upvotes: 1

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