[Python] How to Force WeasyPrint to Generate a Single-Page PDF with Dynamic Height for Large...

I’m using WeasyPrint with FastAPI and Jinja2 to generate a PDF resume from a JSON data structure. The resume is rendered as HTML using a Jinja2 template and converted to PDF with WeasyPrint. My goal is to ensure the PDF is always a single page with an A4 width (210mm) and a dynamic height that adjusts to the content, even if the content is large. However, when the content is extensive (e.g., many experience entries or long descriptions), the PDF splits into two pages, which I want to avoid.

What I’ve Tried Jinja2 Template (resume.html)

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>{{ resume.basicDetails.name }} - {{ resume.basicDetails.position }}</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Source+Sans+Pro:300,400,600">
<style>
@page {
size: 210mm auto;
margin: 5mm;
padding: 0;
}
html, body {
margin: 0;
padding: 0;
font-family: 'Source Sans Pro', sans-serif;
line-height: 1.4;
color: #333;
width: 210mm;
height: auto;
page-break-inside: avoid;
}
.container {
width: 100%;
max-width: 210mm;
height: auto;
padding: 10mm;
page-break-inside: avoid;
}
.section, .entry, .header, .achievements, .skills {
page-break-inside: avoid;
}
/* Additional styles for sections, entries, etc. */
</style>
</head>
<body>
<div class="container">
<div class="header">
<h1 class="name">{{ resume.basicDetails.name|upper }}</h1>
<div class="title">{{ resume.basicDetails.position }}</div>
<!-- Contact info, summary, experience, education, skills, etc. -->
</div>
<!-- Other sections -->
</div>
</body>
</html>


Python Code (generate_resume_from_json)

from weasyprint import HTML, CSS
from fastapi.templating import Jinja2Templates
import os
import uuid

async def generate_resume_from_json(resume_data):
templates = Jinja2Templates(directory="templates")
PDF_DIR = "generated_pdfs"
os.makedirs(PDF_DIR, exist_ok=True)
filename = f"resume_{uuid.uuid4().hex}.pdf"
pdf_path = os.path.join(PDF_DIR, filename)

# Format resume_data into structured format
formatted_data = {
"basicDetails": { /* Name, position, email, etc. */ },
"summary": resume_data.get("Professional Summary", "")[:150],
"experience": [ /* Limited to 2 entries with 2 bullets each */ ],
"education": [ /* Limited to 1 entry */ ],
"skills": resume_data.get("Skills", [])[:8],
"certifications": [ /* Limited to 2 entries */ ],
"projects": [ /* Limited to 1 entry */ ]
}

html_content = templates.get_template("resume/resume.html").render(resume=formatted_data)

try:
HTML(string=html_content, base_url=os.path.dirname(os.path.abspath(__file__))).write_pdf(
pdf_path,
stylesheets=[CSS(string='''
@page {
size: 210mm auto;
margin: 5mm;
padding: 0;
}
@media print {
html, body {
width: 210mm;
height: auto !important;
margin: 0;
padding: 0;
page-break-inside: avoid;
font-size: 12px;
}
.container, .section, .entry, .header, .achievements, .skills {
page-break-inside: avoid;
}
.section { margin-bottom: 5mm; }
.entry { margin-bottom: 3mm; }
}
''')]
)
return {"filename": filename, "pdf_path": pdf_path}
except Exception as e:
print(f"Error: {str(e)}")
return None


The Problem Despite using size: 210mm auto in @page and page-break-inside: avoid on html, body, and major containers, the PDF splits into two pages when the content is large (e.g., multiple experience entries with long descriptions). I want a single-page PDF with a dynamic height that grows to fit all content, even if it exceeds the standard A4 height (297mm).

What I’ve Tried

• Set size: 210mm auto in both the template and WeasyPrint CSS to allow dynamic height.
• Applied page-break-inside: avoid and break-inside: avoid to html, body, and all major containers.
• Reduced font sizes (e.g., 12px) and margins (e.g., 5mm) to make the content more compact.
• Ensured height: auto !important on html and body.

However, the PDF still breaks into two pages for large content. I suspect WeasyPrint is defaulting to an A4 height (297mm) for pagination, ignoring the auto height.

Questions

• How can I force WeasyPrint to generate a single-page PDF with a dynamic height that adjusts to the content?
• Are there specific CSS properties or WeasyPrint options to prevent page breaks entirely?
• Could the issue be related to how WeasyPrint interprets size: auto or my content layout (e.g., floated skills or block-level sections)?

Expected Outcome A single-page PDF with an A4 width (210mm) and a height that expands to fit all content, even if it’s longer than 297mm, without any page breaks.

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