Don't forget to replace "self.image" by your image field name from your model ex ( self.cover ) replace Product by your model name works pretty well :)
Small snippet that will resize all images before they uploaded to the server.
Used to check if a field of an object has changed. This is probably most useful in the save method.
**[Improved and Released as Save The Change.](https://github.com/karanlyons/django-save-the-change)** Django 1.5 added the `update_fields` `kwarg` to `Model.save()`, which allows the developer to specify that only certain fields should actually be committed to the database. However, Django provides no way to automatically commit only changed fields if they're not specified. This mixin keeps track of which fields have changed from their value in the database, and automatically applies `update_fields` to update only those fields.
Overridden save() method that adds Gravatar support for a user with a profile photo field (and presumably an email field). Checks to see if user has provided a photo. If not, then query Gravatar for a possible photo. Finally, if Gravatar does not have an appropriate photo for this user, then use whatever default photo is available (in this case, 'users/photos/default_profile_photo.png'... change as necessary).
If you want unique values for a slug field, but don't want to bother the user with error messages, this function can be put into a model's save function to automate unique slugs. It works by appending an integer counter to duplicate slugs. The item's slug field is first prepopulated by slugify-ing the source field. If that value already exists, a counter is appended to the slug, and the counter incremented upward until the value is unique. For instance, if you save an object titled Daily Roundup, and the slug daily-roundup is already taken, this function will try daily-roundup-2, daily-roundup-3, daily-roundup-4, etc, until a unique value is found. Call from within a model's custom save() method like so: `unique_slug(item, slug_source='field1', slug_field='field2')` where the value of field slug_source will be used to prepopulate the value of slug_field. Comments appreciated!
A simple way to add `date_created` and `date_modified` timestamps to a model. Adds a `date_created` timestamp when the object is first created and adds a `date_modified` timestamp whenever the item is saved. **Note:** You might be tempted instead to use: `date_created=models.DateTimeField(default=datetime.now())` but that won't work as Python will calculate `datetime.now()` only once when it interprets your model. This means that every object created will get the same `date_created` timestamp until you restart your server.
Save method, useful for automate pdf files creation if you want to use the file in database.
Needed a function to check if any field in an instance has changed. If so update a datetime field to now to keep track of changes. This function is an override of the save function in the model.
How to validate your model at save using the pre_save signal. from http://groups.google.com/group/django-developers/browse_thread/thread/eb2f760e4c8d7911/482d8fd36fba4596?hl=en&lnk=gst&q=problem+with+Model.objects.create#482d8fd36fba4596
See [link](http://www.djangosnippets.org/snippets/2005/) for description. Note: Requires Django 1.2.
Add a Save and view next button to your admin change form. Put the code at [link](http://www.djangosnippets.org/snippets/2006/) in a file called myapp/templates/admin/myapp/change_form.html Note: Requires Django 1.2.
I wanted to make the objects of a particular model approvable and store the timestamp of when that happened. In other frameworks/languages, I used to combined those in one "approved_at" field, which would be NULL if an object was currently unapproved. I tried different approaches to implement this in django, and this is the best I came up with so far. Basically, the code in __setattr__ makes sure that the field, once set, will not be updated again. Overriding setattr__() could also be a solution to determining if a field value has changed in save(), a question that seems come up from time to time in #django.
Watch out! Previous versions of this snippet (without the values list) were vulnerable to SQL injection attacks. The "correct" solution is probably to wait until [ticket 4102](http://code.djangoproject.com/ticket/4102) hits the trunk. But here's my temporary fix while we wait for that happy day. Django's model.save() method is a PITA: 1. It does a SELECT first to see if the instance is already in the database. 2. It has additional database performance overhead because it writes all fields, not just the ones that have been changed. 3. It overwrites other model fields with data that may be out of date. This is a real problem in concurrent applications, like almost all web apps. If you just want to update a field or two on a model instance which is already in the database, try this: update_fields(user, email='[email protected]', is_staff=True, last_login=datetime.now()) Or you can add it to your models (see below) and then do this: user.update_fields( email='[email protected]', is_staff=True, last_login=datetime.now()) To add it to your model, put it in a module called granular_update, then write this in your models.py: import granular_update class User(models.Model): email = models.EmailField() is_staff = models.BooleanField() last_login = models.DateTimeField() update_fields = granular_update.update_fields
This takes the "easier to ask forgiveness than permission" approach to making sure your model's slug is unique. If the model's slug is empty, make a slug from the model's 'name' field. We assume that it is a conflicting slug that is throwing the IntegrityError, in which case if the slug does not end with '-' followed by a number then append '-2'. If the slug does end with '-' followed by a number then capture that final number, increment it by one, save the new slug value and try savin g again.