Hello,
I have found an error, and I created a minimal working example. The minimal
working example starts with the very first example from Platypus user guide:
from reportlab.platypus import SimpleDocTemplate, Paragraph, Spacer
from reportlab.lib.styles import getSampleStyleSheet
from reportlab.lib.pagesizes import A4
from reportlab.lib.units import inch
PAGE_HEIGHT = A4[1]
PAGE_WIDTH = A4[0]
styles = getSampleStyleSheet()
Title = "Hello world"
pageinfo = "platypus example"
def myFirstPage(canvas, doc):
canvas.saveState()
canvas.setFont('Times-Bold', 16)
canvas.drawCentredString(PAGE_WIDTH / 2.0, PAGE_HEIGHT - 108, Title)
canvas.setFont('Times-Roman', 9)
canvas.drawString(inch, 0.75 * inch, "First Page / %s" % pageinfo)
canvas.restoreState()
def myLaterPages(canvas, doc):
canvas.saveState()
canvas.setFont('Times-Roman', 9)
canvas.drawString(inch, 0.75 * inch, "Page %d %s" % (doc.page, pageinfo))
canvas.restoreState()
def go():
Story = [Spacer(1, 2 * inch)]
style = styles["Normal"]
for i in range(100):
bogustext = ("This is Paragraph number %s. " % i) * 20
p = Paragraph(bogustext, style)
Story.append(p)
Story.append(Spacer(1, 0.2 * inch))
doc = SimpleDocTemplate("phello.pdf")
doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages)
go()
If I change it to this (e.g. generate two identical files):
doc = SimpleDocTemplate("phello.pdf")
doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages)
doc = SimpleDocTemplate("phello2.pdf")
doc.build(Story, onFirstPage=myFirstPage, onLaterPages=myLaterPages)
then it builds phello.pdf correctly, but builds a totally empty phello2.pdf
(960 bytes, a single white empty page).
It is hard to explain as it is, but something even more interesting happens
if you try to make them totally independent, and create a copy of the story
as well:
import copy
doc = SimpleDocTemplate("phello.pdf")
doc.build(copy.copy(Story), onFirstPage=myFirstPage, onLaterPages=myLaterPages)
doc = SimpleDocTemplate("phello2.pdf")
doc.build(copy.copy(Story), onFirstPage=myFirstPage, onLaterPages=myLaterPages)
This will render phello.pdf correctly, and it will throw this error when
rendering phello2.pdf:
Traceback (most recent call last):
File "C:\Projects\test\test2.py", line 48, in
go()
File "C:\Projects\test\test2.py", line 45, in go
doc.build(copy.copy(Story), onFirstPage=myFirstPage,
onLaterPages=myLaterPages)
File
"C:\Users\nagyl\.virtualenvs\test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py",
line 1314, in build
BaseDocTemplate.build(self,flowables, canvasmaker=canvasmaker)
File "C:\Users\nagyl\.virtualenvs\
test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py", line
1079, in build
self.handle_flowable(flowables)
File "C:\Users\nagyl\.virtualenvs\
test-NC9-O-tN\lib\site-packages\reportlab\platypus\doctemplate.py", line
958, in handle_flowable
raise LayoutError(ident)
reportlab.platypus.doctemplate.LayoutError: Flowable This is Paragraph number 6. This is Paragraph
number 6. This(439.27559055118115 x 72) too large on page 1 in frame
'normal'(439.27559055118115 x 685.8897637795277) of template 'First'
And finally, here is the "solution" that solves all problems:
def go():
def create_story():
Story = [Spacer(1, 2 * inch)]
style = styles["Normal"]
for i in range(100):
bogustext = ("This is Paragraph number %s. " % i) * 20
p = Paragraph(bogustext, style)
Story.append(p)
Story.append(Spacer(1, 0.2 * inch))
return Story
doc = SimpleDocTemplate("phello.pdf")
doc.build(create_story(), onFirstPage=myFirstPage,
onLaterPages=myLaterPages)
doc = SimpleDocTemplate("phello2.pdf")
doc.build(create_story(), onFirstPage=myFirstPage,
onLaterPages=myLaterPages)
This does not throw an error, and it renders both files correctly. But I do
not see why this last version works, and the previous one (that uses
copy.copy) does not.
I was looking for an explanation in the user guide. I was looking for a
note, telling me that a story can be used for document generation only
once. But there is no such thing in the docs. Or maybe I just did not find
it. Can somebody please explain what is happening here?
Environment details: Python 3.10.1 amd64 on Windows, reportlab 3.6.6
Thanks,
Laszlo
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