The latest articles on DEV Community by SAMUELVANUNU (@samuelvanunu). https://dev.to/samuelvanunu https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4013434%2F6fc36036-30dd-430f-a40e-f5c6c20e5a60.png https://dev.to/samuelvanunu en SAMUELVANUNU Fri, 03 Jul 2026 10:46:43 +0000 https://dev.to/samuelvanunu/i-built-a-file-analyzer-during-my-summer-break-heres-what-i-learned-5di7 https://dev.to/samuelvanunu/i-built-a-file-analyzer-during-my-summer-break-heres-what-i-learned-5di7 <h2> The Idea </h2> <p>I wanted a summer break project that wasn't just another to-do app. Something that would touch a few different skills: backend API design, error handling, PDF generation, and a bit of frontend — without getting too ambitious to finish.</p> <p>The result: a <strong>File Analysis &amp; Report System</strong> built with FastAPI. You upload a file (or several), it detects the type, runs a type-specific analyzer, and hands back a structured report — either as JSON or as a downloadable PDF.</p> <h2> What It Does </h2> <ul> <li>Supports 7 file types: <code>.py</code>, <code>.js</code>, <code>.json</code>, <code>.csv</code>, <code>.xml</code>, <code>.yaml</code>, <code>.md</code> </li> <li>Each type gets its own analyzer: <ul> <li>Python → <code>ast</code> module for syntax checking and import detection</li> <li>JSON/YAML → parses and reports validity + top-level keys</li> <li>CSV → column consistency checks</li> <li>XML → element tree parsing</li> <li>Markdown → heading/link/code-block counting</li> </ul> </li> <li>Single or batch upload, with a live web UI</li> <li>PDF export (single file or combined batch report)</li> <li>Dockerized — <code>docker run</code> and you're up</li> </ul> <h2> A Few Things I'd Do Differently </h2> <p><strong>1. Design for compactness from the start.</strong><br> My first PDF export put each file on its own page. For 10 files, that's 11 pages, mostly blank. I only noticed how wasteful it looked once I actually printed a preview — the fix was switching from forced page breaks to a flowing layout, which cut page count by ~70%.</p> <p><strong>2. Error handling isn't optional, it's the whole point.</strong><br> The one thing that broke the app the most during testing was assuming a file would parse cleanly. A single malformed JSON or an unclosed parenthesis in Python would 500 the whole request if I didn't wrap the parsing in try/except. Once I made <em>every</em> analyzer fail gracefully into the report format instead of throwing, the whole system got a lot more trustworthy.</p> <p><strong>3. .gitignore matters more than I thought.</strong><br> Early on I accidentally committed my entire <code>venv/</code> folder — 3,500+ files. Lesson learned: set up <code>.gitignore</code> before your first commit, not after.</p> <h2> Tech Stack </h2> <ul> <li> <strong>Backend:</strong> FastAPI, Python's <code>ast</code>/<code>csv</code>/<code>xml</code>/<code>json</code> stdlib modules, PyYAML</li> <li> <strong>PDF generation:</strong> ReportLab, with a Unicode font for proper character support</li> <li> <strong>Frontend:</strong> Vanilla HTML/CSS/JS (no framework — kept it simple), localStorage for history</li> <li> <strong>Containerization:</strong> Docker + docker-compose</li> </ul> <h2> Try It </h2> <p>Repo's here if you want to poke around or use it: <a href="https://github.com/SamulVanunu/dosya-analiz-sistemi" rel="noopener noreferrer">github.com/SamulVanunu/dosya-analiz-sistemi</a></p> <p>Happy to hear feedback, especially on the analyzer architecture — I tried to keep it modular (a <code>BaseAnalyzer</code> interface) so adding new file types is just a few lines of code, but I'm curious if there's a cleaner pattern.</p> python fastapi webdev showdev