Helpful pre commit hooks for Python and Django

Helpful pre commit hooks for Python and Django

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  Thomas Aglassinger https://roskakori.at Helpful pre-commit hooksfor Python and Django
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  What is pre-commit? ● Aframework to manage git pre-commit hooks. ● To perform quality check on code before accepting a commit. ● Many handy hooks available through it. ● Helps you catch many (often minor issues) before they make it into the repository.
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  How to getpre-commit ● Visit https://pre-commit.com/ ● Various methods to install: – Plain Python: pip install pre-commit – Anaconda: conda install -c conda-forge pre-commit – Ubuntu: sudo apt-get install pre-commit – MacOS: brew install pre-commit
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  Configuration ● Add a file“.pre-commit-config” ● Add the github repositories and hooks you want to run before each commit. ● Example: ● Run “pre-commit install” ● Hooks are checked on “git commit ...” and commit in IDE ● Manually run hooks using “pre-commit run --all-files” exclude: "^.idea" repos: - repo: git://github.com/pre-commit/pre-commit-hooks rev: v3.2.0 hooks: - id: trailing-whitespace - id: end-of-file-fixer - id: mixed-line-ending args: ["--fix=auto"]
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  Configuration ● Add a file“.pre-commit-config” ● Add the github repositories and hooks you want to run before each commit. ● Example: exclude: "^.idea" repos: - repo: git://github.com/pre-commit/pre-commit-hooks rev: v3.2.0 hooks: - id: trailing-whitespace - id: end-of-file-fixer - id: mixed-line-ending args: ["--fix=auto"] Regex for files and folders not to check Source code repository and version of hooks to use Hooks to use Parameters for a specific hook
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  Standard hooks –Text files ● - repo: git://github.com/pre-commit/pre-commit-hooks rev: v3.2.0 ● trailing-whitespace: remove white space at end of line in text files ● mixed-line-ending: detect or fix mixed line endings (e.g developers on Windows and Unix working on same code) ● end-of-file-fixer: Ensures that text files end with a newline character.
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  Example hooks
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  Standard hooks –Unwanted files ● check-byte-order-marker: rejects text files starting with UTF-8 BOM (as created by various Microsoft tools like Notepad, causing many Unix tools to fail) ● check-added-large-files: rejects large files; possibly specify what is large: args: ["--maxkb=768"] ● Check-merge-conflict: refuse to commit before all merge conflicts are resolved
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  Standard hooks -Python ● check-ast: check Python syntax ● requirements-txt-fixer: sorts entries in requirements.txt ● debug-statements: refuse to commit calls to breakpoints() and imports of debugger
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  Standard hooks –Syntax checks ● check-json ● check-toml ● check-xml ● check-yaml
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  Pretty print Python ● Usingblack (opinionated): https://github.com/psf/black ● Configure using pyproject.toml - repo: https://github.com/ambv/black rev: stable hooks: - id: black [tool.black] line-length = 120 include = '.pyi?$' exclude = ''' /( .eggs | .git | venv | build | dist )/ '''
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  Sort imports consistently ● Usingisort: https://github.com/timothycrosley/isort ● Configure using setup.cfg ● Can be tricky to work with black → see example to the right - repo: https://github.com/timothycrosley/isort rev: 5.4.2 hooks: - id: isort [tool:isort] # Use project line length. line_length = 120 # Packages from own projetc default_section = THIRDPARTY known_first_party = mytool, niftysite # Use same style as black. force_grid_wrap=0 include_trailing_comma = True multi_line_output=3 use_parentheses=True # Skip virtual environments. skip_glob = venv
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  Flake8 – SemanticPython check ● Find unused imports, shadowed variables, string formatting, unreachable code, … ● Configure using setup.cfg - repo: https://gitlab.com/pycqa/flake8 rev: 3.8.3 hooks: - id: flake8 [flake8] max-line-length = 120 ignore = E203, W503 exclude = .git build dist venv docs/conf.py
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  Prettier – Prettyprint various formats for web development ● Supports JavaScript, CSS, Markdown, HTML, GraphQL, YAML and others by means of plugins ● Does not work with Django HTML templates → exclude using “.prettierignore” (uses same format as .gitignore) - repo: https://github.com/prettier/prettier rev: 2.0.5 hooks: - id: prettier **/coverage.xml **/templates/**/*.html
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  Summary ● Pre-commit is easyto install and configure. ● Solves minor minor issues arising when multiple developers work on the same code. ● Plenty of available hooks.