How to understand includes in Rails with ajax-datatables-rails

I'm using ajax-datatables-rails and want to use an associated model in the datatable file, I want to use the include() method. However, it's not that simple. According to https://github.com/jbox-web/ajax-datatables-rails, their include() example is extremely complicated and goes far beyond what I'm trying to do.

I have a model called Page and one called Book for example, and I just simply want to use Pages.include(:book) so that I can call page.book in my view later on.

How can I accomplish that using their scenario? Here's what I tried, but it didn't work:

# app/datatables/example_datatable.rb
  # Allow the use of helpers in JSON response.
  def_delegators :@view, :link_to, :book_path

  def view_columns
    # Declare strings in this format: ModelName.column_name
    # or in aliased_join_table.column_name format
    @view_columns ||= {
      # id: { source: "User.id", cond: :eq},
      # name: { source: "User.name"}

      position: { source: "Page.position"},
      book_name: { source: "Page.book.book_name"},
    }
  end

  def data
    records.map do |record|
      {
        # example:
        # id: record.id,
        # name: record.name
        position: record.position,
        book_name: link_to("#{record.book.book_name}", book_path(record), remote: true),
      }
    end
  end

  private

  def get_raw_records
    # insert query here
    Page.includes(:book).references(:book).distinct
  end

If I just left it at Pages.includes(:book) then I get an error in my datatable only when I attempt to use the search/filter textbox. Otherwise, things are displayed just fine.

The error that I get states:

Unknown column 'pages.book' in 'where clause'

In their example, they stated that references(:related_model) is in here, but I'm not exactly sure how to swing it using my simple one-model-association.

Solution

According to the ajax-datatables-rails README it looks like you might need to:

put Book.name into your @view_columns instead of Page.book.name
use joins(:book) instead of include/references