Feb 27, 2019

Creating dynamic headers in Reportlab

When writing code to make a report, you never truly know what you are going to get into. In a recent Python project, I was using the excellent ReportLab libraryand things were going smoothly. But then I needed make a header that would appear on every page. This isn’t took bad – you just create a function that goes on the document when you build it. But the API doesn’t support that terribly well – the function that you give to the Document object takes the Document and the Canvas as the only parameters… but I have content to put in there!

In the dusty part of my brain I remembered currying functions from reading several years ago. They are also called “partial functions”. As a surprise to no one, Python 3 has a standard library function for this. As I combined that with how I knew the header had to be made, I was impressed how simple it seemed to be. The code isn’t complicated at all!

Here is a Gist with how I set this up. Some understanding of ReportLab is assumed, but I think it works well. You can do something similar for a footer as well. Actually you can have both render in the same function.

About the Author

Mike Hostetler profile.

Mike Hostetler

Principal Technologist

Mike has almost 20 years of experience in technology. He started in networking and Unix administration, and grew into technical support and QA testing. But he has always done some development on the side and decided a few years ago to pursue it full-time. His history of working with users gives Mike a unique perspective on writing software.

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