gene_regulations.rb

# Note that this action responds to fracked up datatable parameters.
  # If you need to use this for some other reason (HTML, etc), you
  # might want to consider moving it into it's own method 
  # (datatable or something).
  def index
    # These are the columns, in the correct order, used by datatables
    cols = [:gene_name, :gene_symbol, :gene_id, :interaction, :chromosome]

    @gene_regulations = 
      if params[:kind] == 'up_regulated'
        @compound.gene_regulations.up_regulated
      else
        @compound.gene_regulations.down_regulated
      end.includes(:articles)

    # This needs to be here so we can only count the regulations by kind,
    # but we don't have any searches applied yet
    @total_count = @gene_regulations.count

    if params[:search][:value].present?
      query_cols = cols.map { |c| "`#{c}` LIKE :q" }
      @gene_regulations = \
        @gene_regulations.where(query_cols.join(" OR "), 
                                q: "%#{params[:search][:value]}%")
    end

    # This has to be here, it needs to be the count before any
    # pagination has been done and it needs to take into account 
    # search terms.
    @filter_count = @gene_regulations.count

    if params[:order].present?
      params[:order].each do |number, order_col|
        column = cols[order_col[:column].to_i]
        @gene_regulations = \
          @gene_regulations.order("`#{column}` #{order_col[:dir]}")
      end
    end

    if params[:start].present?
      @gene_regulations = @gene_regulations.offset(params[:start].to_i)
    end
    if params[:length].present?
      @gene_regulations = @gene_regulations.limit(params[:length].to_i)
    end
  end