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Dear Diary, an Encrypted Command-Line Diary with Python
In my last post, I wrote about how to work with encrypted SQLite databases with Python. As an example application of these libraries, I showed some code fragments for a fictional diary program. Because I was thinking the examples directory of the peewee repo was looking a little thin, I decided to flesh out the diary program and include it as an example.
In this post, I'll go over the diary code in the hopes that you may find it interesting or useful. The code shows how to use the peewee SQLCipher extension. I've also implemented a simple command-line menu loop. All told, the code is less than 100 lines!
Saturday morning hacks: Building an Analytics App with Flask
A couple years back I wrote about building an Analytics service with Cassandra. As fun as that project was to build, the reality was that Cassandra was completely unsuitable for my actual needs, so I decided to switch to something simpler. I'm happy to say the replacement app has been running without a hitch for the past 5 months taking up only about 20 MB of RAM! In this post I'll show how to build a lightweight Analytics service using Flask.
Encrypted SQLite Databases with Python and SQLCipher
SQLCipher, created by Zetetic, is an open-source library that provides transparent 256-bit AES encryption for your SQLite databases. SQLCipher is used by a large number of organizations, including Nasa, SalesForce, Xerox and more. The project is open-source and BSD licensed, and there are open-source python bindings.
A GitHub user known as The Dod was kind enough to contribute a sqlcipher playhouse module, making it a snap to use Peewee with SQLCipher.
In this post, I'll show how to compile SQLCipher and the sqlcipher3 python bindings, then use peewee ORM to work with an encrypted SQLite database.
Saturday morning hacks: Adding full-text search to the flask note-taking app
In preparation for the fourth and final installment in the "Flask Note-taking app" series, I found it necessary to improve the search feature of the note-taking app. In this post we will use SQLite's full-text search extension to improve the search feature.
To recap, the note-taking app provides a lightweight interface for storing markdown-formatted notes. Because I frequently find myself wanting to take notes on the spur of the moment, the note-taking app needed to be very mobile-friendly. By using twitter bootstrap and a hefty dose of JavaScript, we made an app that matches our spec and manages to look good doing it!
In part 2, we added email reminders and check-able task lists to the note-taking app. We also converted the backend to use flask-peewee's REST API extension, which made it easy to add pagination and search. And that is how I've left it for the last three months or so.
Below is a screenshot of the latest version of the notes app. The UI is much cleaner thanks to a stylesheet from bootswatch. The bootswatch stylesheet works as a drop-in replacement for the default bootstrap CSS file.
All together, the note-taking app has the following features:
- Flexible pinterest-style tiled layout that looks great on a variety of screen sizes.
- Easy to create notes and reminders from the phone.
- Notes support markdown and there is also a simple WYSIWYM markdown editing toolbar.
- Links are converted to rich media objects where possible (e.g. a YouTube URL becomes an embedded player).
- To-do lists (or task lists) can be embedded in notes.
- Email reminders can be scheduled for a given note.
- Simple full-text search.
- Pagination.
You can browse or download the finished code from part 2 in this gist. If you're in a hurry, you can find all the code from this post in this gist.
In case you were curious, I've been using the notes app for things like:
- Bookmarking interesting sites to read later.
- Creating short to-do lists or writing down particular items to get from the store, etc.
- Writing down interesting dreams or ideas I get in the middle of the night.
- Appointment reminders, reminders to call people, etc.
- Saving funny cat pics.
- Writing down ideas for programming projects.
- Saving code snippets or useful commands.
SQLite: Small. Fast. Reliable. Choose any three.
SQLite is a fantastic database and in this post I'd like to explain why I think that, for many scenarios, SQLite is actually a great choice. I hope to also clear up some common misconceptions about SQLite.
JavaScript Canvas Fun: Pong
Earlier this week I rediscovered some old games I'd written, and I realized that I had not yet done a JavaScript version of Pong. I did versions of Tetris and Snake, perennial favorites of mine to implement, but somehow I'd forgotten about Pong. I think Pong was probably the first game I ever tried to copy, and it has a special place in my early-programmer's memory.
So I set out last night to put together a JavaScript canvas version of Pong. You can find a playable version in the post.
Completely un-scientific benchmarks of some embedded databases with Python
I've spent some time over the past couple weeks playing with the embedded NoSQL databases Vedis and UnQLite. Vedis, as its name might indicate, is an embedded data-structure database modeled after Redis. UnQLite is a JSON document store (like MongoDB, I guess??). Beneath the higher-level APIs, both Vedis and UnQLite are key/value stores, which puts them in the same category as BerkeleyDB, KyotoCabinet and LevelDB. The Python standard library also includes some dbm-style databases, including gdbm.
For fun, I thought I would put together a completely un-scientific benchmark showing the relative speeds of these various databases for storing and retrieving simple keys and values.
Here are the databases and drivers that I used for the test:
- UnQLite: unqlite-python (ctypes)
- Vedis: vedis-python (ctypes)
- GDBM: standard library (C)
- BerkeleyDB (b-tree and hash-table): bsddb3 (C)
- KyotoCabinet (b-tree and hash-table): kyotocabinet (C++)
- LevelDB: plyvel (Cython)
- RocksDB: pyrocksdb (Cython)
- SQLite: standard library (C and Python)
- Redis: redis-py (Python) -- this one is just for fun!
I'm running these tests with:
- Linux 3.14.4
- Python 2.7.7 (Py2K 4 lyfe!)
- SSD
For the test, I simply recorded the time it took to store 100K simple key/value pairs (no collisions). Then I recorded the time it took to read back all these values. The results are in seconds elapsed:
Saturday morning hacks: Revisiting the notes app
My post from last month, Saturday Morning Hack, a Little Note-Taking App with Flask, was pretty well-received. Since I've made a number of improvements to the app, I thought I would write one more post to share some of the updates I've made to this project, in the hopes that they may be of interest to you.
A live demo is up and running on Python Anywhere, so feel free to check that out before continuing on with the post: http://beetlejuicer.pythonanywhere.com/
To briefly recap the previous post, I discussed how I built a lightweight note-taking app which I could use from my phone or desktop. It has a nice ajax-ey interface and some simple markdown helpers written with javascript. In addition to supporting markdown, it also supports oembed for automatically embedding YouTube videos and the like. Here is what it looked like when we left off a few weeks ago:
And this is how it looks now!
So what's new? Well, I've made a couple changes under-the-hood, and added some entirely new features to the UI.
- Allow creation of Task Lists with checkbox inputs.
- Create reminders that will send me an email at the appointed time.
- Built a RESTful API to interact with the
Notemodel. Thanks to flask-peewee everything comes "for free". - Added search.
- Added pagination (using Ajax).
This was super fun to hack on so I thought I'd share the new code and describe how I added these features. Honestly, I didn't really end up adding much in terms of implementation. Huey handles scheduling and sending the email reminders, even automatically retrying messages that fail to send. Similarly, Flask-Peewee's REST API provides search and pagination out-of-the-box, so all I had to do was write the JavaScript to communicate with it. Thanks to these libraries, I was able to focus on the things that made this project unique, and hopefully you enjoy reading about the code.
Read the rest of the post for the details.
Using SQLite Full-Text Search with Python
In this post I will show how to use SQLite full-text search with Python (and a lot of help from peewee ORM). We will see how to index content for searching, and how to order search results using two ranking algorithms.
Last week I migrated my site from Postgresql to SQLite. I had been using Redis to power my site's search, but since SQLite has an awesome full-text search extension, I decided to give it a try. I am really pleased with the results, and being able to specify boolean search queries is an added plus. Here is a brief overview of the types of search queries SQLite supports:
- Simple phrase: peewee would return all docs containing the word peewee.
- Prefix queries: py* would return docs containing Python, pypi, etc.
- Quoted phrases: "sqlite extension"
NEAR: peewee NEAR sqlite would return docs containing the words peewee and sqlite with no more than10intervening words. You can also specify the max number of intervening words, e.g. peewee NEAR/3 sqlite.AND,OR,NOT: sqlite OR postgresql AND NOT mysql would return docs about high-quality databases (just trollin).
Check out the full post for details on adding full-text search to your project.
Saturday morning hack: personalized news digest with boolean query parser
Because I had so much fun writing my last Saturday morning hack, I thought I would share another little hack. I was thinking that I really enjoy my subscription to Python weekly and wouldn't it be great if I had a personal email digest containing just the types of things that interest me? I regularly cruise reddit and hacker hater news but in my opinion there's a pretty low signal-to-noise ratio. Occasionally I stumble on fascinating content and that's what keeps me coming back.
I wanted to write an app that would search the sites I read and automatically create an email digest based on search terms that I specified. I recently swapped my blog over to SQLite and I love that the SQLite full-text search extension lets you specify boolean queries. With that in mind, I decided that I would have a curated list of boolean search queries which would be used to filter content from the various sites I read. Any articles that match my search would then be emailed to me.
Here are some of my search terms, which I am viewing in the flask-peewee admin interface:
If you're interested in learning how to build your own version of this project, check out the rest of the post.