prawnto displaying tables that don't break when new page - ruby-on-rails

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 the next then continue on. I have put the table in a transaction so I can roll back then print it if the height will fit on curent page but how do I get the table height?
I have this code at the moment
pdf.transaction do
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.move_down 20
#pdf.rollback
end
Any help on this would be great. Or any other way to do this ?
Best Regards
Rick

Answer 1

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

Answer 2

#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 3

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 4

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'