![]() Moz_bookmarks = Table('moz_bookmarks', metadata, If the table doesn’t have a primary key, then you can do this to hack it: If it’s a proper database with a primary key, this will work great. This tells SqlAlchemy to attempt to load the “moz_bookmarks” table automatically. For our purposes, the most interesting line is as follows: I would recommend setting it to False when you put your code in production. This causes SqlAlchemy to send all the SQL it generates to stdout, which is quite handy for debugging purposes. In the create_engine call, we set echo to True. If you try to use it in place and you have Firefox open, you may have issues as your code may interrupt Firefox or vice-versa. Just copy that file into the location that you’ll be using for the scripts in this article. On my Windows XP machine, it’s in the following location: “C:\Documents and Settings\Mike\Application Data\Mozilla\Firefox\Profiles\fault”. If you have it installed, go looking for it as it makes an excellent testbed for this sort of thing. This database comes from Mozilla Firefox. Note that we have a “places.sqlite” file. In this snippet, we import a few handy classes and utilities from sqlalchemy that allow us to define such things as an engine (a type of connection/interface to the database), metadata (a table catalog) and a session (a “handle” to the database that allows us to query it). Moz_bookmarks = Table('moz_bookmarks', metadata, autoload=True) Let’s start out with the long version and then do it “declaratively”.įrom sqlalchemy import create_engine, MetaData, Tableįrom sqlalchemy.orm import mapper, sessionmakerĮngine = create_engine('sqlite:///%s' % dbPath, echo=True) We’ll start off with the autoload method and then show the long way in the next section.īefore we begin though, it needs to be noted that there are two methods for configuring SqlAlchemy: a long-hand way and a declarative (or “shorthand” way. The easy (or short) way is to use SqlAlchemy’s autoload functionality, which will introspect the table and pull out the field names in a rather magical way. The first way is the long way, in which you define each and every field along with its type. SqlAlchemy has two ways to define a databases columns. ![]() This article will show you how to connect to them. If my experience is any indication, you’ll probably be spending more time working with databases that you didn’t create than with ones that you did. In this article, we’re going to look at how to use SqlAlchemy to connect to pre-existing databases. ![]() In this case, you end up using Python syntax to execute SQL rather than straight SQL and you can use the same code to access multiple database backends (if you’re careful). SqlAlchemy is an object-relational mapper (ORM), which means that it takes SQL constructs and makes them more like the target language. My favorite way to access databases with Python is to use the 3rd party package, SqlAlchemy. Python even provides a sqlite database library that’s built into the main distribution (since 2.5). Accessing databases with Python is a simple process. ![]()
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