Most Django views e.g. the Django admin will not be able to handle a validation error in the save method, so your users will get 500 errors. You should do validation on the model form or on the model, and raise ValidationError there. Then call save() only if the model form data is ‘good enough … Read more
Here is example of what you want to achieve: http://docs.djangoproject.com/en/dev/topics/db/models/#extra-fields-on-many-to-many-relationships In case link ever breaks: from django.db import models class Person(models.Model): name = models.CharField(max_length=128) def __str__(self): # __unicode__ on Python 2 return self.name class Group(models.Model): name = models.CharField(max_length=128) members = models.ManyToManyField(Person, through=”Membership”) def __str__(self): # __unicode__ on Python 2 return self.name class Membership(models.Model): person = … Read more
Ditto what everyone is saying about transactions. That said… ActiveRecord as of Rails 2.1 keeps track of the attribute values of an object. So if you have an attribute total, you will have a total_changed? method and a total_was method that returns the old value. There’s no need to add anything to your model to … Read more
This actually works, even without items in the list: @Html.DisplayNameFor(model => model.Names[0].FullName) It works because MVC parses the expression instead of actually executing it. This lets it find that right property and attribute without needing there to be an element in the list. It’s worth noting that the parameter (model above) doesn’t even need to … Read more
Essentially Model and View Model are both simple classes with attributes. The main objective of these classes are to describe (to “Model”) an object for their respective audiences that are respectively the controller and the view. So you are completely right when you say To my understanding, it’s a kind of Model that has a … Read more
Rails 3.1 introduced update_column, which is the same as update_attribute, but without triggering validations or callbacks: http://apidock.com/rails/ActiveRecord/Persistence/update_column
I think the easiest from a logical and efficiency point of view is using the queryset’s exists() function, documented here: https://docs.djangoproject.com/en/stable/ref/models/querysets/#django.db.models.query.QuerySet.exists So in your example above I would simply write: if User.objects.filter(email = cleaned_info[‘username’]).exists(): # at least one object satisfying query exists else: # no object satisfying query exists
Here is what I would do: Create a migration to change the table name (database level). I assume your old table is called corps. The migration content will be: class RenameCorpsToStores < ActiveRecord::Migration def change rename_table :corps, :stores end end Change your model file name, your model class definition and the model associations: File rename: … Read more
With the advent of Django 1.7, there is now a new update_or_create QuerySet method, which should do exactly what you want. Just be careful of potential race conditions if uniqueness is not enforced at the database level. Example from the documentation: obj, created = Person.objects.update_or_create( first_name=”John”, last_name=”Lennon”, defaults={‘first_name’: ‘Bob’}, ) The update_or_create method tries to … Read more
You can also use this format: validates :foo, length: {minimum: 5, maximum: 5}, allow_blank: true Or since your min and max are the same, the following will also work: validates :foo, length: {is: 5}, allow_blank: true