visaplan.zope.reldb 1.0.0.dev2

Configure a Data source name for Zope

visaplan.zope.reldb

This package simply provides the configuration of a Data source name (DSN), e.g. for use with SQLAlchemy.

For the heavy lifting of integration of database transactions of your relational database (like PostgreSQL or whatever) with the ZODB, you’ll likely want to use something like zope.sqlalchemy, which in turn requires sqlalchemy to talk to the database. However, zope.sqlalchemy doesn’t offer a configuration method for the DSN. This packages offers to store this DSN in the Zope configuration file (parts/clientN/etc/zope.conf).

The idea is: You might have several instances of your Zope (for production, testing, development …), and every now and then you replicate the productive data. With the DSN stored in the ZODB, you’d have this information replicated as well, which might not work for you; you might have different databases on the same database server, or the production server connects to the database by socket which is not possible in your development instance, or whatever.

Features

• Stores a DSN string in the Zope configuration and provides a get_dsn function.

• With SQLAlchemy installed,

  • creates an Engine and a DBSession, and

  • provides an optional .legacy.SQLWrapper context manager class which sports a few simple insert, update, delete, select and query methods

• With zope.sqlalchemy installed as well, registers that DBSession for the transaction machinery integration.

Installation

Add the package to your product requirements somehow; since we’ll need to add a product configuration as well, you’ll most likely add it to your eggs value in your buildout script (buildout.cfg):

[buildout]

...

eggs =
    your.fancy.product
    visaplan.zope.reldb

Add a product configuration there as well, containing your data source name:

[buildout]

...

[instance_base]
...
zope-conf-additional =
    <product-config reldb>
    dsn postgresql+psycopg2://localhost/mydb
    </product-config>

(We follow the convention used by the UnifiedInstaller here; your section(s) might be named differently.)

After running bin/buildout and restarting your Zope instance, the product configuration should have been added to your zope.conf file(s), and your.fancy.product can read the DSN string by calling visaplan.zope.reldb.get_dsn (or, if you have SQLAlchemy, directly use visaplan.zope.reldb.engine.engine).

Remark

“But, can’t my product simply do all this by itself?!”

Sure. Having this as a package helps / helped us to switch a whole bunch of packages from usage of Zope database adapters (stored in the ZODB) to sqlalchemy (with a DSN configured in the zope.conf file(s)).

Contribute

• Issue Tracker: https://github.com/visaplan/zope.reldb/issues

• Source Code: https://github.com/visaplan/zope.reldb

Support

If you are having issues, please let us know; please use the issue tracker mentioned above.

License

The project is licensed under the GPLv2.

Futher reading

• The SQLAlchemy documentation about Database URLs

Contributors

• Tobias Herp, [e-mail]

Changelog

1.0.0 (unreleased)

• Initial release. [tobiasherp]