I have an array field in my PostrgreSQL database of type text. Is there a way to map this into a Django model ?
You might want to look into django-dbarray on github. It adds support for postgresql array fields.
I haven't used it before, but it looks like you just need to do:
from django.db import model
import dbarray
class ProfilingTestRun(models.Model):
function = models.CharField(max_length=64)
runtimes = dbarray.FloatArrayField()
One of the other nice options is http://django-orm.readthedocs.org/ --- a library that adds bindings to many native postgres types.
Main drawback of django-orm is that as of today it has no working support for south.
djorm-ext-pgarray also offer queries
http://www.niwi.be/2012/10/07/postgresql-array-fields-with-django/
Native support for PostgreSQL specific model fields is coming soon to Django (in the django.contrib.postgres.fields module):
https://docs.djangoproject.com/en/dev/ref/contrib/postgres/fields/#arrayfield
https://github.com/django/django/pull/2485 : The corresponding pull request
Since Django 1.8 there is a django.contrib.postgress module that adds support to array fields among other PostgreSQL data types.
For example you can do something like this:
from django.contrib.postgres.fields import ArrayField
from django.db import models
class GoGame(models.Model):
board = ArrayField(ArrayField(models.IntegerField(),size=19),size=19)
you have to subclass model.Field and write input and output methods.
http://docs.djangoproject.com/en/dev/howto/custom-model-fields/#custom-database-types
Related
My app is full of statements like this:
from my_app.model import Customer
While it works, I'll like to have a way to reference the current app without hard coding the app name into the import. Something like:
from keyword_for_current_app.model import Customer
Is there a clean way of achieving this with Django?
This is more of a python question than a Django one as it relates to how imports work. As far as I know, there isn't a way to do it as you describe, unless you change the structure of your files.
However, it isn't impossible to do something using Django's functionality to dynamically import models. You could swap some of this with importlib if you need a more general import rather than just returning the model class:
from django.apps import apps
# option 1
model = apps.get_model('app.Model')
# option 2
def get_model(model_name):
return apps.get_model(f'myapp.{model_name}')
# option 3
def get_model(model_name):
for model in apps.get_models():
if model.__name__ == model_name:
return model
The problem with option 1 for your use case is that you still need to specify the app name. Option 2 is an improvement, but you are hardcoding the app name into the function. Option 3 is the best, but might be problematic if you have models with the same name but in different apps/tables.
In my opinion, you should import each model explicitly at the top of your files. This is the cleanest and most readable way - if someone were to read your code, they would expect models to be imported this way.
I was referring this link : Django: Get model from string?
. And, I found there is a way to do this by using apps.get_model. But,In my scenario, the model can be from other apps. So, I can't actually name the app_name here. Is there any way to do this ?
If you don't care which app the model comes from, you can do it the following way:
from django.apps import apps
def get_model_from_any_app(model_name):
for app_config in apps.get_app_configs():
try:
model = app_config.get_model(model_name)
return model
except LookupError:
pass
model = get_model_from_any_app('SomeModelName')
But in Django models in different apps can have the same name, i.e. your project can have model Post in your blog app and model Post in your news app etc.
So this way you can end up with not the model you expect, if they have duplicate names across apps (i.e. you probably should not do it this way, just think why in the world would you want a semi-random model?).
Docs which explain the code:
https://docs.djangoproject.com/en/2.0/ref/applications/#django.apps.apps.get_app_configs
https://docs.djangoproject.com/en/2.0/ref/applications/#django.apps.AppConfig.get_model
Just a simple question.
After I connect my django app to a remote database, I don't need to use Model.py to create tables in the database, then what is the function for Model.py at that moment?
If you want to use the Django ORM, you'll need to create models in the models.py file that match your remote database. If you don't want django creating or deleting tables on this DB, the managed=False option needs to be set for each model.
https://docs.djangoproject.com/en/1.11/ref/models/options/#managed
As you said after running migrations all tables in models.py file will be created. Later on, if you want to do some database operations, you may be using Django ORM. If you don't have models.py you won't be able to do such operations.
For example:
To create an entry to the table MyModel.
from your_app.models import MyModel
MyModel.objects.create(<field_name>=<value>)
I hope this gives you some idea.
I want to develop a server side of an app that holds users.
Of course I need a table in database holding the user information.
At first I may write
class User(models.Model): # using django models
userid = ...
password = ...
which gives me a database table containing userid and password.
However, I might want to add some attributes (maybe Credit, Birthday...so on) to each user in the future. I just can't think up all of them right now. And I can't know what attributes I would really need in the future.
How can I deal with it?
There's already a user table in Django. This table is automatically create when you first apply the migration with 'manage.py migrate' command.
In database schema, this table is listed as auth_user and you can import it into Django with the following command
from django.contrib.auth.models import User
Django provides a default model for User. you can use it like this.
from django.contrib.auth.models import User
and as per your second query. you can do so by creating another model and adding a ForeignKey or OneToOneField of User model to link it with each user.
class Customuserprofile(models.Model):
user=models.OneToOneField(settings.AUTH_USER_MODEL)
credit=models.CharField()
birthday=models.DateTimeField()
well, if you want to add some field to the User you can use AbstractUser or AbstractBaseUser model read this that explain the differences and give a example https://simpleisbetterthancomplex.com/tutorial/2016/07/22/how-to-extend-django-user-model.html#abstractbaseuser
I'd like to retrieve automatically, in a loop, the names of the models located in a specific Django app inside my project. Does someone know how to do that ?
Best Regards
Guillaume
from django.db import get_models, get_app
app = get_app('myappname')
models = get_models(app)