My Models has a FK to translations and also a many 2 many to categories which also them are translated With this code I concatenate the translation of the categories and allow the changelist to order them. works only on mysql but you can adapt to your DB SET SESSION is required by mysql.
This code provides a mixin and decorator which, when used together, can provide advisory locking on model methods. It provides locking by using MySQL's advisory lock system. See the example at the bottom of the code. This is a convenient and easy way to guarantee your model methods have exclusive access to a model instance. The LockableObjects class requires a MySQL backend, but it could be modified to use other back-end locking systems. The lock name generation in `LockableObject.get_lock_name()` could be altered to create much more complex locking schemes. Locking per-object, per-method for example.. Lock attempts have a timeout value of 45 seconds by default. If a timeout occurs, EnvironmentError is raised. **See the bottom of the script for an example** > **Instructions:** * **1:** Place the code in locking.py somewhere in your path * **2:** In your models.py (or any script with an object you want to lock): `from locking import LockableObject, require_object_lock` * **3:** In the model you want locking for, add the `LockableObject` mixin * **4:** Decorate the method you want to be exclusively locked with `@require_object_lock`
Auto-incremented primary keys are the default in Django and they are supported natively in most databases but for anything more complex things are less trivial. DB sequences are not standard, may not be available and even if they are, they are typically limited to simple integer sequence generators. This snippet bypasses the problem by allowing arbitrary auto-generated keys in Python. The implementation needs to determine whether an IntegrityError was raised because of a duplicate primary key. Unfortunately this information is not readily available, it can be found only by sniffing the DB-specific error code and string. The current version works for MySQL (5.1 at least); comments about how to determine this in other databases will be incorporated in the snippet.
Check database constraints after dirty import
*WARNING* This is *extremely* slow. This snippet allows you to easily prevent *most* race conditions (if used properly). Feel free to extend on top of this as you like, I'd appreciate any comments to [email protected]
Drops all tables in MySQL table (either managed by Django or not). Useful when resetting the database with no CREATE DATABASE privileges. MySQL-only.
This example shows, how to use database views with django models. NewestArticle models contains 100 newest Articles. Remember, that NewestArticle model is read-only. Tested with mysql.
A quick and dirty hack for composite indexing if you need it. Drop this into a models.py or some other place where it'll be loaded along with the rest of Django on start up. Then add an _index_together tuple specifying the fields you want a composite index on.
A python implementation of the old MySQL PASSWORD() function. This is insecure. There is a reason MySQL changed this in version 4.1. Use it only if you have to!
Based on [http://www.djangosnippets.org/snippets/662/](http://www.djangosnippets.org/snippets/662/) and updated to be runnable as custom django management command. Also added option support for --exclude=someapp --exclude=otherapp.SomeModel From original description: InnoDB tables within MySQL have no ability to defer reference checking until after a transaction is complete. This prevents most dumpdata/loaddata cycles unless the dump order falls so that referenced models are dumped before models that depend on them. Caveats 1. You use this snippet to dump the data and the built in manage.py loaddata to load the fixture output by this program. A similar solution could be applied to the XML processing on the loaddata side but this sufficed for my situations. 2. This code does not handle Circular or self-references. The loaddata for those needs to be much smarter
i use this to get the pk of a record before creation, in my scenario to name an uploaded image: def UPLOADTO( i,n ): if not i.id: id = get_nextautoincrement( i.__class__ ) else: id = i.id return str(id)+'.jpg'
While django provides the `django_admin.py cleanup` script, if sessions get out of control sometimes you have to go lower level to get everything cleaned up. If the problem gets out of hand and you hit the resource limits of the machine, it is very difficult to get anything done in the database. Attached is SQL code which was used to cleanup 27GB of expired session data in 3h. Run it like this to make sure it runs to completion: `nohup mysql --user=username --password=password --host=hostname database < delete_expired_sessions.sql` nohup causes the script to run detached from a terminal, so if your session gets disconnected it will keep running.
I was trying to create a custom field to use the mysql encrypt() function on some data I wanted to store in the DB. initcrash on IRC pointed me to [this code](https://tracpub.yaco.es/cmsutils/browser/trunk/db/fields.py?rev=66) which I butchered as best as my little brain could. Amazingly enough I got it working (thanks to a couple answers from initcrash). If anyone can clean this up that would be great. I'm also trying to figure out how I can a) create password reset link in the admin interface for this field without displaying the field or b) decrypt it so that the password field is pre-populated with the decrypted password. Otherwise it is submitting the encrypted string as a new password. Anyways, I'm only a week or two into Django with no python experience so any suggestions are very welcome. Hope this helps someone!
sometimes,you need to lock one or more table to ensure the integrity of data.may be it's help to you.
Sometimes you need to prevent concurrent access to update/calculate some properties right. Here is (MySQL) specific example to lock one table with new object manager functions.
21 snippets posted so far.