python-csv-quality-checker

A small but real-world Python CLI that checks a CSV file for common data-quality issues and produces a report.

What it does

• Validates required columns
• Checks missing values
• Validates types (int/float/date/string)
• Checks duplicates on a chosen key
• Outputs a JSON report and a human-friendly summary

Tech

• Python 3.10+
• Typer (CLI)
• Pydantic (schema)
• Pytest (tests)

Quick start

cd python-csv-quality-checker
python -m venv .venv
# Windows: .venv\Scripts\activate
source .venv/bin/activate

pip install -r requirements.txt

# Run against the sample file
python -m dqcheck check sample/customers.csv --schema sample/schema.json --key id --out report.json

Example output

• Console summary with counts and top problems
• report.json with full details

Commands

python -m dqcheck --help
python -m dqcheck check --help

Running tests

pytest -q

Project layout

• dqcheck/ – application code
• tests/ – unit tests
• sample/ – sample CSV + schema JSON

Notes

• This is intentionally small, but structured like a production CLI project.
• Great place to add enhancements: rules engine, HTML report, Great Expectations integration, etc.