How to access an instance variable from a do block?

Question

The following code does not work. It says undefined method 'table_name' for nil:NilClass

@members = Members.all

table member_list_rows do      
  if @members.table_name == members
    row(0).background_color = '3498db'
  end
end

Full code

class MemberPdf < Prawn::Document
  def initialize(members, view, allcount)
    super(top_margin: 50)
    if members.size != allcount
      @warn = " (Not all members)"
    else
      @all = " All"
    end
    text "Showing#{@all} #{members.size} Members", size: 18, style: :bold, align: :center, color: "636363"
    text "#{@warn}", size: 11, align: :center, color: "858585"
    @members = members
    @view = view
    member_list
  end

  def member_list
    move_down 20
    table member_list_rows do
      self.row(0).align = :center
      if @members.table_name == "members"
        row(0).background_color = '3498db'
      else

      end

      row(0).text_color = "FFFFFF"
      self.row_colors = ["DDDDDD", "FFFFFF"]
      self.header = true
      #self.cell.text_color = "B3B3B3"
      row(0).columns(0).style size: 20
    end
  end

  def member_list_rows
    [["Name", "Awardunit", "Address", "Contact", "Level of Entry", "Current Award", "Disabled?"  ]] +
    @members.map do |member|
      [member.name, member.awardunit.name, member.address, member.name, member.entrylvl, member.currentaward, @view.yesno(member.disabled)]
    end
  end
end

Members controller

    if params[:commit] == "Clear"
        params[:q] = nil
    end

    respond_to do |format|
        format.html
        format.pdf do
            pdf = MemberPdf.new(Member.search(params[:q]).result.order( 'name ASC' ), view_context, Member.all.size)
            send_data pdf.render, filename: "Members_List.pdf", type: "application/pdf", disposition: "inline"
        end
    end

Maybe you can puts the initial text to the console instead of using text in your PDF-file, that might allow you to see how many members you have. However, I still fail to see where table_name should be defined. @members will just hold an Array which will not answer to your table_name even if it is not nil. Maybe you can add another puts @members.count inside member_list_rows to help with debugging? — Patru
– Patru, Commented Mar 25, 2014 at 9:46

Pavan · Accepted Answer · 2014-03-25 08:18:58Z

3

It is due to @members is nil.You are doing it wrong.

Change this

@members = Members.all #Wrong

to

@members = Member.all #Right

Always remember,the Model name should be singular.

Those are called Naming Conventions. For more information,read these Style guides(Ruby and Rails)

edited Mar 25, 2014 at 8:18

answered Mar 25, 2014 at 8:06

Pavan

33.6k8 gold badges53 silver badges78 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

THpubs Over a year ago

Sorry, its a mistake in the question. In the actual code its correct

Pavan Over a year ago

Can you Post the full code where that Snippet belongs to?

Pavan Over a year ago

Where do you have this line @members = Member.all? In your members_controller?

THpubs Over a year ago

Yes. Then it pass members to this class. This piece of code use that data to render a list of member. The member data is coming to this class and im sure of it because the list gets rendered.

Pavan Over a year ago

@EApubs Ok Can you please post your members_controller also?

|

rindek · Accepted Answer · 2014-03-25 11:48:07Z

1

Most likely table method is changing context, in which you don't have access to the @members instance variable anymore. This can be achieved easily by this sample code:

def do_stuff(&block)
  cls = Class.new
  cls.instance_eval(&block)
end

@test_var = "test_var"

do_stuff { puts @test_var }

You will receive nothing, because @test_var does not exist in the cls.

answered Mar 25, 2014 at 11:48

rindek

1265 bronze badges

1 Comment

toro2k Over a year ago

Reading the Prawn source code it seems you are quite right.

Shrutee · Accepted Answer · 2014-03-25 08:10:48Z

0

Am not sure what you are doing with "table member_list_rows". Didn't get that. In the third line though, it should be

if @members.table_name == "members"

answered Mar 25, 2014 at 8:10

Shrutee

1,9251 gold badge12 silver badges13 bronze badges

Collectives™ on Stack Overflow

How to access an instance variable from a do block?

3 Answers 3

7 Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

7 Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related