prawnto displaying tables that don't break when new page

Question

I have a variable number of tables with variable number of rows and I want to have them displaying one after the other but if a table doesn\'t fit on the current page put it on

Answer 1

I'm a Prawn beginner, so this might not be the best solution, but it should work.

You can get the table height if you consider the font size and vertical padding and the number of records you have in @data and you can get the current cursor position by calling Prawn::Document.cursor method.

Having these two numbers you should be able to check whether the table fits on this page or not. If not, just start a new one (by calling Prawn::Document.start_new_page method).

Otherwise the table will break automatically and will continue on the next page.

Answer 2

Thanks Igor

I am currently setting the current page and then in the transaction after the new table has been rendered and before the roll back setting new_page variable. Then i can roll back and chek if the new page var > current page var and if it is start new page and print the table. See code below.

The problem is now the pdf.start_new_page says error but if i just take the pdf.rollback line out it works. See error below.

Any ideas any one or any easier ways, there must be one!!

thanks rick

@current_page = pdf.page_count

pdf.transaction do 
  pdf.move_down 20

  pdf.table @data,
    :font_size  => 12, 
    :border_style => :grid,
    :horizontal_padding => 10,
    :vertical_padding   => 3,
    :border_width       => 2,
    :position           => :left,
    :row_colors => ["FFFFFF","DDDDDD"]

  @the_next_page = pdf.page_count
  pdf.rollback

end 

if @the_next_page > @current_page

  pdf.start_new_page

  pdf.table @data,
    :font_size  => 12, 
    :border_style => :grid,
    :horizontal_padding => 10,
    :vertical_padding   => 3,
    :border_width       => 2,
    :position           => :left,
    :row_colors => ["FFFFFF","DDDDDD"]
end 

The error

> You have a nil object when you didn't expect it!
The error occurred while evaluating nil.identifier

Extracted source (around line #158): 

155: end



RAILS_ROOT: C:/InstantRails/rails_apps/Macrotec-Application

Application Trace | Framework Trace | Full Trace 
c:/InstantRails/ruby/lib/ruby/gems/1.8/gems/prawn-core-0.7.1/lib/prawn/document.rb:302:in `go_to_page'
c:/InstantRails/ruby/lib/ruby/gems/1.8/gems/prawn-core-0.7.1/lib/prawn/document/internals.rb:128:in `finalize_all_page_contents'
c:/InstantRails/ruby/lib/ruby/gems/1.8/gems/prawn-core-0.7.1/lib/prawn/document/internals.rb:127:in `each'
c:/InstantRails/ruby/lib/ruby/gems/1.8/gems/prawn-core-0.7.1/lib/prawn/document/internals.rb:127:in `finalize_all_page_contents'
c:/InstantRails/ruby/lib/ruby/gems/1.8/gems/prawn-core-0.7.1/lib/prawn/document.rb:344:in `render'
C:/InstantRails/rails_apps/Macrotec-Application/app/views/quotations/show.pdf.prawn:158:in `_run_prawn_app47views47quotations47show46pdf46prawn'

Answer 3

@current_page = pdf.page_count

@roll = pdf.transaction do 
  pdf.move_down 20

  pdf.table @data,
    :font_size  => 12, 
    :border_style => :grid,
    :horizontal_padding => 10,
    :vertical_padding   => 3,
    :border_width       => 2,
    :position           => :left,
    :row_colors => ["FFFFFF","DDDDDD"]

  pdf.rollback if pdf.page_count > @current_page

end 

if @roll == false

  pdf.start_new_page

  pdf.table @data,
    :font_size  => 12, 
    :border_style => :grid,
    :horizontal_padding => 10,
    :vertical_padding   => 3,
    :border_width       => 2,
    :position           => :left,
    :row_colors => ["FFFFFF","DDDDDD"]
end

I hope this works for you as for me :-)

Answer 4

4 years later... :)

As @m-x wrote it, rollback was disabled for security reason, like "group", and is still not implemented. So, here how I deal with break pages for tables :

Big and simple table (one row per data)

Just use header option

pdf.table @data,
  header: true, # You can use 'header: 2' if your header take two rows
  font_size: 12, 
  border_style: :grid,
  horizontal_padding: 10,
  vertical_padding: 3,
  border_width: 2,
  position: :left,
  row_colors: ["FFFFFF","DDDDDD"]

Small table or complexe table

• make table
• check if you need break page
• draw table

With your example :

t = pdf.make_table @data,
  font_size: 12, 
  border_style: :grid,
  horizontal_padding: 10,
  vertical_padding: 3,
  border_width: 2,
  position: :left,
  row_colors: ["FFFFFF","DDDDDD"]

if cursor - t.height < 0
  start_new_page
end

t.draw

Hope that helps