Chapter 62 — Files and Data Processing

SmartNotes has a problem: every time the program stops, all notes vanish. Phase 5 gave your objects behavior, structure, and Pythonic integration. Phase 6 gives them survival.

This chapter teaches you to read, write, and transform data using Python's file I/O and data format libraries. You will export notes as Markdown, save entire notebooks as JSON, generate CSV spreadsheets, and build processing pipelines that chain these operations together.

You already learned databases in Part 2 (Chapters 21, 21A, 21B). This chapter focuses on the Python code that processes data before it reaches a database: the files, formats, and pipelines that form the first layer of persistence.

#	Lesson	Focus	SmartNotes Deliverable
1	Reading and Writing Text Files	pathlib.Path, open(), with statement	Export notes as Markdown files
2	Structured Data: JSON	json.loads(), json.dumps(), typed parsing	Save/load notebook as JSON
3	Tabular Data: CSV	csv.reader, csv.DictReader, encoding	Export/import notes as CSV
4	Processing Pipelines	Read, transform, write chains with error handling	Filter-and-export pipeline
5	SmartNotes File Manager Capstone	Full TDG cycle from scratch	FileManager with all formats

Prerequisites: Chapters 42-61 (all of Phases 1-5). You should be comfortable with dataclasses, classes, the TDG cycle, and the verification stack (ruff, pyright, pytest).