Skip to content

Level 5 / Project 09 - Template Report Renderer

Home: README

Learn Your Way

Read Build Watch Test Review Visualize Try
— This project — — Flashcards — Browser

Quick Recall: This project uses string parsing and pattern matching to find placeholders in text. Before starting, make sure you can: split a string on a delimiter and use str.replace() to substitute values into a template string (Level 1, Project 04 - Log Line Parser).

Estimated time: 75 minutes

Focus

  • report generation by template blocks

Why this project exists

This project gives you level-appropriate practice in a realistic operations context. Goal: run the baseline, alter behavior, break one assumption, recover safely, and explain the fix.

Run (copy/paste)

Use <repo-root> as the folder containing this repository's README.md.

cd <repo-root>/projects/level-5/09-template-report-renderer
python project.py --template data/report_template.txt --data data/report_data.json --output data/rendered_report.txt
pytest -q

Expected terminal output

Report rendered: 25 lines written
7 passed

Expected artifacts

  • data/rendered_report.txt
  • Passing tests
  • Updated notes.md

Checkpoint: Baseline code runs and all tests pass. Commit your work before continuing.

Alter it (required) — Extension

  1. Add {{IF NOT condition}}...{{END IF}} blocks for negated conditionals.
  2. Add a {{DATE}} placeholder that inserts the current date.
  3. Support nested variable access like {{config.max_retries}}.
  4. Re-run script and tests.

Break it (required) — Core

  1. Use a template with {{variable}} that is not in the data JSON.
  2. Create an {{EACH items}} block where items is not a list.
  3. Capture the first failing test or visible bad output.

Fix it (required) — Core

  1. Replace missing variables with [MISSING: variable] instead of crashing.
  2. Skip EACH blocks when the data is not iterable, with a warning.
  3. Add tests for missing variables and non-iterable EACH data.
  4. Re-run until output and tests are deterministic.

Checkpoint: All modifications done, tests still pass. Good time to review your changes.

Explain it (teach-back)

  1. How does render_variables find and replace {{name}} placeholders?
  2. Why are EACH blocks processed before IF blocks?
  3. What regex pattern matches the {{EACH items}}...{{END EACH}} block?
  4. Where do you see template engines in production (Jinja2, Handlebars, Mustache)?

Mastery check

You can move on when you can: - run baseline without docs, - explain one core function line-by-line, - break and recover in one session, - keep tests passing after your change.

← Prev Home Next →