ruby on rails - id nil when select model without no relation -

i have model no relation.

class gridconfig < activerecord::base end 

my question why result of query appended id:nil columns?

gridconfig.select(:fontsize) 

result is

#<gridconfig id: nil, fontsize: "12px"> 

is there options this?

thank you.

---

i want find records , pick columns. , send client.

user_key = params[:user_key] grid_id = params[:grid_id]  @config = gridconfig.where(['user_key = ? , grid_id = ?', user_key, grid_id])     .select(:model_id, :fontsize, :displaycount, :columnmodel)  # checked @config variables @ point , found nil:id...  @config = @config.index_by(&:model_id)  # , want makes indexed model_id [{"model":{...}},{"model2" : {...}}, {}]  respond_to |format|     format.json { render json: @config } end 

you can use pluck method select columns array, index first column.

@config = gridconfig.where(user_key: params[:user_key], grid_id: params[:grid_id])    .pluck(:model_id, :fontsize, :displaycount, :columnmodel)  @config = @config.index_by{ |x| x[0] }