CODEWITHSUNDEEP
ruby-on-rails-3mongodbmongomapper
Shamoon
Shamoon

Reputation: 43589

Querying distinct with MongoMapper

How do I query distinct with MongoMapper? My query is:

subscribedToThread = Comment.where(:subscribe_thread => 1).all

But this will return many objects with the same user_id. I need to return just a distinct user_id. Is this possible?

Upvotes: 2

Views: 1563

Answers (4)

Jon Kern
Jon Kern

Reputation: 3235

For the original post, try this:

subscribedToThread = Comment.where(:subscribe_thread => 1).distinct(:user_id)

I wanted to count the number of distinct entries when the user chose type = "Other" from the list and entered a custom name (so that I could consider adding more common choices to the list).

InteriorInfo.where(type: 'Other').distinct(:name).sort.each{|i| puts "%3d %s" % [InteriorInfo.where(name: i).count, i]}

Resulting in (snippet)

  6 AED
  1 Alarm Panel
 16 Basement Access

Upvotes: 0

Tyler Brock
Tyler Brock

Reputation: 30156

I think you will need to drop down to the ruby driver in order to do this as I don't think you can do this with MongoMapper itself:

subscribedToThread = Comment.collection.distinct("user_id", {:subscribe_thread => 1})

Calling the collection method on a model returns the collection as would be provided by the Ruby driver directly so you can issue a distinct query using the syntax below:

collection.distinct(key, query = nil)

You can read more about it here

Upvotes: 7

Sandip Mondal
Sandip Mondal

Reputation: 921

Try this

subscribedToThread = Comment.where(:subscribe_thread => 1).fields(:user_id).collect(&:user_id).uniq

It will show you list of uniq user_id

Upvotes: 1

three
three

Reputation: 8478

Yes, you can do so:

subscribedToThread = Comment.where(:subscribe_thread => 1).fields(:user_id).all.compact!.unique!

This will nil every field but user_id which you then uniq!,ie you remove all doubles and then compact! all nil

http://mongomapper.com/documentation/plugins/querying.html#fields

Upvotes: 2

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