Get Unique contents from Ruby Hash

Question

I have a Hash @estate:

    [#<Estate id: 1, Name: "Thane ", Address: "Thane St.", created_at: "2013-06-21 16:40:50", updated_at: "2013-06-21 16:40:50", user_id: 2, asset_file_name: "DSC02358.JPG", asset_content_type: "image/jpeg", asset_file_size: 5520613, asset_updated_at: "2013-06-21 16:40:49", Mgmt: "abc">,
    #<Estate id: 2, Name: "Mumbai", Address: "Mumbai St.", created_at: "2013-06-21 19:13:59", updated_at: "2013-06-21 19:14:28", user_id: 2, asset_file_name: "DSC02359.JPG", asset_content_type: "image/jpeg", asset_file_size: 5085580, asset_updated_at: "2013-06-21 19:13:57", Mgmt: "abc">] 

Is it possible to make new Hash with unique values according to the user_id: 2 , because currently 2 elements have the user_id same ie 2, I just want it once in the hash, what should I do ?

Answer 1

Here is an sample example to get you a good start:

h = [ { a: 2, b: 3}, { a: 2, c: 3 } ]
h.uniq { |i| i[:a] }
# => [{:a=>2, :b=>3}]

Answer 2

It seems to be something like a has_many relation between User model and Estate model, right? If I understood you correctly, than you need in fact to group your Estate by user_id :

PostgreSQL:

 Estate.select('DISTINCT ON (user_id) *').all

MySQL:

 Estate.group(:user_id).all

PS I'd not recommend to select all records from a database and then process them with Ruby as databases handle operations with data in much more efficient way.