Recent Posts (Page 6)

Git: Rebase an old branch incrementally

You worked on a sizeable feature branch some time ago but left it to focus on other things. Now you’re ready to pick it up, so you want to rebase it onto your updated main branch. But when you try that, you’re presented with an overwhelming number of merge conflicts.

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Boost Your DX bundle deal

I released Boost Your Git DX nearly two weeks ago. It’s the second in my “Boost Your DX” series, following last year’s Boost Your Django DX. Both books aim to improve your development experience with their respective tool.

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“Boost Your Git DX” out now

My new book, Boost Your Git DX is out now, on my birthday 🥳. It’s taken nearly a year of work with four months in early access.

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Git: Show the initial (root) commit

To show the initial, or root, commit* of your repository, use:

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My fourth appearance on Django Chat

I’ve once more had the pleasure of joining Carlton and Will on the Django Chat podcast, in Episode #146. We spoke on Tuesday, just hours after Django 5.0 alpha 1 was released, on several topics:

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Git: Don’t create .gitkeep files, use .gitignore instead

Git only tracks files, not directories. It will only create a directory if it contains a tracked file. But sometimes you need to “track” a directory, to ensure it exists for fresh clones of a repository. For example, you might need an output directory called build.

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Django: Move a template tag library into builtins

Django’s template engine has an underappreciated builtins option that selects libraries to preload in every template. Making a library a builtin avoids the need for an explicit {% load %} tag whenever you use its tags or filters. Putting key libraries in builtins can shorten your templates and make development a little bit faster.

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Introducing flake8-logging

The Python standard library’s logging module is a go-to for adding observability to applications. Many tools also integrated with it or enhance its capabilities, such as structlog and Sentry.

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Git: Clear unreachable files from the .git directory

Every object you commit in Git is copied into its object store, within the .git directory. If you undo a commit, the commit object and associated file objects remain in Git’s object store, at least for a while. The normal garbage collection process will clean them out, by default in 30 days.

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Docker: Clean up unused stuff on your development machine

Docker keeps all objects (images, containers, volumes, etc.), with no automatic cleanup. It thus consumes disk space without bound, which can eventually fill up your development machine.

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Git: Output the top-level directory of the current repository

To output the root directory of the current repository, use:

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Git: Output just the current branch name

To print just the name of the current branch, use:

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Django: The perils of string_if_invalid in templates

Django’s template engine has a string_if_invalid option that replaces missing variable lookups with a string of your choice:

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Python: Profile a section of code with cProfile

When trying to improve a slow function or module, it’s always a good idea to profile it. Here’s a snippet for quickly profiling a section of code with Python’s cProfile module, in two flavours. It’s adapted from the cProfile documentation’s Profile example. I have used versions of this snippet over the years to narrow in on performance issues.

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Python type hints: How to pass Any for unused parameters in tests

When you create a function to match an interface, it often needs to accept parameters that it doesn’t use. Once you introduce type hints, testing such functions can become a little irksome as Mypy will require all arguments to have the correct types. Your tests can end up creating unused objects only to match the tested function’s signature. Here’s a technique to avoid that work.

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Django: Clean up unused code with Vulture

As projects evolve, old functionality gets removed. Often such deletions are incomplete, leaving in their wake unused functions, classes, and other code objects. Unused code is clutter that brings no joy: it hinders comprehension, taxes codebase-wide quality improvements, and can sometimes lead to errors if later used.

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Django: Flush out test flakiness by randomly ordering QuerySets

Sometimes code depends on the order of a QuerySet whilst not specifying an order. This can lead to random, flaky test failures because databases can return rows in any order when none is specified. The problem is made worse by some databases, notably PostgreSQL, which nearly always return rows in insert order, but occasionally use a different order when a table has had recent deletions.

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Django: A version of json_script for pre-serialized JSON strings

Django’s json_script template filter is a convenient and safe way to pass a larger amount of data to JavaScript. I covered it in my post last year How to Safely Pass Data to JavaScript in a Django Template.

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Python type hints: modernized error messages in Mypy 1.4.0

Mypy 1.4.0 was released last week (2023-06-20). I’m happy to see it includes three improvements that modernize error messages with newer type hint syntax:

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Django: A security improvement coming to format_html()

Can you spot the problem with this Django snippet?

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“Boost Your Git DX” available in early access

I’m happy to announce that my new book, Boost Your Git DX is available now, in “early access”.

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Git: Detect an in-progress cherry-pick, merge, rebase, or revert

To detect if a certain operation is in progress in a Git repository, use git rev-parse like so:

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Django: Avoid database queries in template context processors

Django’s template engine allows you to augment template contexts with context processors. These are functions that take the current request and return a dictionary to be merged into the context:

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Django: Parametrized tests for all model admin classes

Here’s an application of “test smarter, not harder”, as per Luke Plant’s post. I came up with this recently whilst working on my client Silvr’s project, and I’m pretty proud of it. It should apply to any project using Django’s admin.

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How to download a documentation website with Wget

Sometimes you want to download a whole website so you have a local copy that you can browse offline. When programming, this is often useful for documentation that sites that do not provide downloadable versions, and are not available in offline tools like DevDocs.

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