z3c.rml - Alternative implementation of RML

5.0.1 verified Fri May 01 auth: no python

An alternative implementation of Report Markup Language (RML) for generating PDFs. Provides a Pythonic API to produce RML XML that can be rendered by ReportLab. Current version 5.0.1, requires Python >=3.9. Maintained by the Zope Foundation with a slow release cadence.

pip install z3c-rml

Common errors

error AttributeError: module 'z3c.rml' has no attribute 'story' ↓

cause Incorrect import. The library is structured so that `z3c.rml` is a namespace package; you must import submodules explicitly.

fix

Use from z3c.rml import story instead of import z3c.rml.story.

error ImportError: cannot import name 'RML2PDF' from 'z3c.rml' ↓

cause Trying to import the old class directly from the package root. In modern versions, use `from z3c.rml import rml2pdf`.

fix

Replace from z3c.rml import RML2PDF with from z3c.rml import rml2pdf.

error TypeError: go() takes at least 2 positional arguments (0 given) ↓

cause Calling `rml2pdf.go()` without arguments or with incorrect arguments. The function expects a doc and an output.

fix

Correct usage: rml2pdf.go(doc, output) where doc is a story.DocTemplate and output is a file path or BytesIO.

Warnings

gotcha z3c.rml uses a Pythonic object model, not raw RML XML. Do not try to pass raw RML strings; use the story objects. ↓

fix Use `z3c.rml.story` classes (DocTemplate, Paragraph, etc.) instead of manually constructing XML.

deprecated The old `z3c.rml.rml2pdf` module had different function signatures. In version 5.0, the preferred method is `rml2pdf.go(doc, output)`. The old direct class instantiation may still work but is not recommended. ↓

fix Use `from z3c.rml import rml2pdf; rml2pdf.go(doc, output)`.

gotcha The library expects a `BytesIO` or a file path for output. Passing a string path works, but avoid passing a file-like object that is not seekable. ↓

fix Ensure output is a writable bytes buffer or a string path to a file.

Imports

RML2PDF
wrong
```
from z3c.rml.rml2pdf import RML2PDF
```
correct
```
from z3c.rml import rml2pdf
```
RML2PDF is obtained via the module, not directly imported; use the module-level functions.
story
wrong
```
import z3c.rml.story
```
correct
```
from z3c.rml import story
```
Access story elements via attribute of the module, not submodule import.

Quickstart

Minimal example: create a document, add a paragraph, and render to PDF.

from z3c.rml import rml2pdf, story
from io import BytesIO

# Create a simple RML document (this is a Pythonic representation, not raw XML)
doc = story.DocTemplate(
    pagesize=(595.27, 841.89),  # A4
    title="Hello World"
)
story = doc.story
story.append(story.Paragraph("Hello, World!", style=story.ParagraphStyle(name='Normal')))

# Generate PDF
buf = BytesIO()
rml2pdf.go(doc, buf)
buf.seek(0)
print("PDF generated, size:", len(buf.read()))