All Questions
2,730
questions
134
votes
6
answers
170k
views
How to query database by id using SqlAlchemy?
I need to query a SQLAlchemy database by its id something similar to
User.query.filter_by(username='peter')
but for id. How do I do this? [Searching over Google and SO didn't help]
user507220
111
votes
8
answers
239k
views
How to update() a single model instance retrieved by get() on Django ORM?
I have a function which currently calls Models.object.get(), which returns either 0 or 1 model objects:
if it returns 0, I create a new model instance in the except DoesNotExist clause of the ...
- 6,901
97
votes
6
answers
187k
views
Check if an object exists
I need to check if Model.objects.filter(...) turned up anything, but do not need to insert anything. My code so far is:
user_pass = log_in(request.POST) # form class
if user_pass.is_valid():
...
- 11.3k
95
votes
3
answers
19k
views
models.py getting huge, what is the best way to break it up?
Directions from my supervisor:
"I want to avoid putting any logic in the models.py. From here on out, let's use that as only classes for accessing the database, and keep all logic in external classes ...
- 3,144
86
votes
8
answers
54k
views
Django get list of models in application
So, i have a file models.py in MyApp folder:
from django.db import models
class Model_One(models.Model):
...
class Model_Two(models.Model):
...
...
It can be about 10-15 classes.
How to find ...
- 3,618
79
votes
6
answers
88k
views
Django required field in model form
I have a form where a couple of fields are coming out as required when I don't want them too. Here is the form from models.py
class CircuitForm(ModelForm):
class Meta:
model = Circuit
...
- 1,095
75
votes
4
answers
85k
views
How can I set two primary key fields for my models in Django?
I have a model like this:
class Hop(models.Model):
migration = models.ForeignKey('Migration')
host = models.ForeignKey(User, related_name='host_set')
How can I have the primary key be the ...
- 5,923
73
votes
11
answers
34k
views
Case insensitive unique model fields in Django?
I have basically a username is unique (case insensitive), but the case matters when displaying as provided by the user.
I have the following requirements:
field is CharField compatible
field is ...
- 1,109
68
votes
5
answers
88k
views
Populating django field with pre_save()?
class TodoList(models.Model):
title = models.CharField(maxlength=100)
slug = models.SlugField(maxlength=100)
def save(self):
self.slug = title
super(TodoList, self).save()
...
- 12.2k
65
votes
3
answers
44k
views
How can I iterate over ManyToManyField?
A simple question and yet I can't find an answer for it.
I have a model with a ManyToMany field:
class Stuff(models.Model):
things = models.ManyToManyField(Thing)
then in a different function I ...
- 10.1k
65
votes
1
answer
14k
views
Is it bad practice to include non-validating methods in a pydantic model?
I'm using pydantic 1.3 to validate models for an API I am writing.
Is it common/good practice to include arbitrary methods in a class that inherits from pydantic.BaseModel?
I need some helper methods ...
- 653
51
votes
3
answers
58k
views
Local functions in Python [duplicate]
In the following Python code, I get an UnboundLocalError. As I understand it, local functions share the local variables of the containing function, but this hardly seems to be the case here. I ...
- 115k
47
votes
3
answers
78k
views
ValueError - Cannot assign: must be an instance
I get the following error when I try to run an insert into one of my tables.
Cannot assign "1": "Team.department_id" must be a "Department" instance
Admittedly I'm ...
- 629
46
votes
4
answers
47k
views
Do properties work on Django model fields?
I think the best way to ask this question is with some code... can I do this:
class MyModel(models.Model):
foo = models.CharField(max_length = 20)
bar = models.CharField(max_length = ...
- 75.7k
43
votes
3
answers
72k
views
Restrict django FloatField to 2 decimal places
I am looking for a way to limit the FloatField in Django to 2 decimal places. Has anyone got a clue of how this could be done without having to use a DecimalField?
I tried decimal_places=2, but this ...
- 1,012
43
votes
6
answers
75k
views
How can I change a Django form field value before saving?
if request.method == 'POST':
userf = UsersModelForm(request.POST)
username = userf.data['username']
password = userf.data['password']
passwordrepeat = userf.data['passwordrepeat']
...
- 12.3k
39
votes
5
answers
30k
views
Check if a OneToOne relation exists in Django
Now I'm using django 1.6
I have two models relates with a OneToOneField.
class A(models.Model):
pass
class B(models.Model):
ref_a = models.OneToOneField(related_name='ref_b', null=True)
...
- 18k
36
votes
2
answers
17k
views
How to have two models reference each other Django
I have the following code:
class Game(models.Model):
title = models.CharField(max_length=50)
summery = models.CharField(max_length=500)
key = models.IntegerField()
pin = models....
- 11.3k
28
votes
3
answers
8k
views
Python/Django: synonym for field "type" in database model (reserved built-in symbol)
I created a django project. It contains a model class with a "type" attribute. I think that "type" is the most appropriate term to describe that field, because it defines the kind of the entry.
...
- 29.5k
27
votes
12
answers
89k
views
Cast string to float is not supported in Linear Model
I keep getting this error in my linear model:
Cast string to float is not supported
Specifically, the error is on this line:
results = m.evaluate(input_fn=lambda: input_fn(df_test), steps=1)
If ...
- 401
26
votes
1
answer
10k
views
Django MVC pattern for non database driven models?
I'm just working my way through Django, and really liking it so far, but I have an issue and I'm not sure what the typical way to solve it.
Suppose I have a View which is supposed to be updated when ...
- 5,147
25
votes
12
answers
29k
views
Spacy link error
When running:
import spacy
nlp = spacy.load('en')
the following is printed:
Warning: no model found for 'en'
Only loading the 'en' tokenizer.
/site-packages/spacy/data is empty with the ...
- 1,879
25
votes
9
answers
50k
views
How to store a dictionary in a Django database model's field
I need to save a dictionary in a model's field. How do I do that?
For example I have this code:
def create_random_bill(self):
name_chars = re.compile("[a-zA-Z0-9 -_]")
bill_name = "".join(...
- 20.3k
25
votes
1
answer
3k
views
Trigger Odoo fields_view_get dynamically after all records being loaded and fields_view_get function called
I’d like to trigger the fields_view_get function dynamically after doing some functions. I override the function fields_view_get and return my results. This gets affected on XML view only at first ...
- 1,675
23
votes
2
answers
13k
views
Can you add parameters to Django custom admin actions?
For example (not the case, but just to illustrate) if I wanted to add an action to set a specific field in the selected items to X. Is it possible to add an action to allow X to be entered as opposed ...
- 25.6k
21
votes
1
answer
6k
views
Django models: mutual references between two classes and impossibility to use forward declaration in python
I have defined two models where each one references the other, like so:
class User(models.Model):
# ...
loves = models.ManyToManyField(Article, related_name='loved_by')
class Article(models....
- 2,908
21
votes
4
answers
18k
views
How to assign items inside a Model object with Django?
Is it possible to override values inside a Model?
I am getting 'MyModel' object does not support item assignment.
my_model = MyModel.objects.get(id=1)
print my_model.title
if my_model.is_changed:
...
- 1,469
21
votes
3
answers
22k
views
SQLAlchemy - order_by on relationship for join table
I'm using declarative SQLAlchemy and I have three models: Role, Permission, and RolePermission. In my Role model, I have the following:
class Role(Base):
name = Column(u'NAME', VARCHAR(50), ...
- 31.4k
21
votes
4
answers
9k
views
ForeignKey to abstract class (generic relations)
I'm building a personal project with Django, to train myself (because I love Django, but I miss skills). I have the basic requirements, I know Python, I carefully read the Django book twice if not ...
- 6,003
20
votes
2
answers
12k
views
Default filter in Django model
Is is possible to set a default filter in Django models?
Something like:
class MyModel(models.Model):
timestamp = models.DateTimeField(default=datetime.utcnow)
active = models.BooleanField(...
- 10.9k
20
votes
2
answers
17k
views
Django: Grab a set of objects from ID list (and sort by timestamp)
I have a list of IDs for objects that I need to grab, then I have to sort them by their timestamp. Here's how I was going to do it:
For i in object_ids:
instance = Model.objects.get(id = i)
# ...
- 10.1k
20
votes
3
answers
51k
views
Import data from excel spreadsheet to django model
I'm building a website that'll have a django backend. I want to be able to serve the medical billing data from a database that django will have access to. However, all of the data we receive is in ...
- 399
19
votes
2
answers
22k
views
Python/Django: Adding custom model methods?
Using for example
class model(models.Model)
....
def my_custom_method(self, *args, **kwargs):
#do something
When I try to call this method during pre_save, save, post_save etc, ...
- 6,125
19
votes
1
answer
23k
views
How to use full_clean() for data validation before saving in Django 1.5 gracefully?
I think Django's model validation is a little inconvenient for those models that don't use built-in ModelForm, though not knowing why.
Firstly, full_clean() needs called manually.
Note that ...
- 893
18
votes
5
answers
44k
views
How to load a pre-trained Word2vec MODEL File and reuse it?
I want to use a pre-trained word2vec model, but I don't know how to load it in python.
This file is a MODEL file (703 MB).
It can be downloaded here:
http://devmount.github.io/GermanWordEmbeddings/
- 413
18
votes
3
answers
36k
views
Can I create model in Django without automatic ID?
I need a table without a primary key (in Django it was created automatically). So my question is: Can I create a model without an ID/primary key?
I'm using Django 1.7.
- 566
18
votes
6
answers
52k
views
pydantic exclude multiple fields from model
In pydantic is there a cleaner way to exclude multiple fields from the model, something like:
class User(UserBase):
class Config:
exclude = ['user_id', 'some_other_field']
I am ...
- 13.5k
18
votes
2
answers
35k
views
How to set value of a ManyToMany field in Django?
while learning Django to do web programming,I faced this problem.
I searched Google and Django's official website biut could not find any answer. Please help me.
System environment:
Fedora 18
Python ...
- 381
18
votes
3
answers
9k
views
Is there a way to transparently perform validation on SQLAlchemy objects?
Is there a way to perform validation on an object after (or as) the properties are set but before the session is committed?
For instance, I have a domain model Device that has a mac property. I would ...
- 4,568
17
votes
6
answers
21k
views
How to choose the value and label from Django ModelChoiceField queryset
I was trying to create a django form and one of my field contain a ModelChoiceField
class FooForm(forms.Form):
person = forms.ModelChoiceField(queryset=Person.objects.filter(is_active=True)....
- 3,104
17
votes
3
answers
15k
views
How to run multiple graphs in a Session - Tensorflow API
Tensorflow API has provided few pre-trained models and allowed us to trained them with any dataset.
I would like to know how to initialize and use multiple graphs in one tensorflow session. I want ...
- 918
16
votes
4
answers
50k
views
Django Models Number Field
In Django I'm trying to create a model which will contain a field for player's shirt numbers and was wondering if there is a way to restrict the field to be only numerical inputs. Currently I have in ...
- 199
16
votes
3
answers
12k
views
how to get dict of model objects keyed by field
Assuming I have Django model called 'Blog' with a primary key field 'id', is there a query I can run that will return a dictionary with keys of the id values indexing the Blog model instances?
...
- 3,651
16
votes
2
answers
23k
views
Inserting NULL as default in SQLAlchemy?
I have the following column in SQLAlchemy:
name = Column(String(32), nullable=False)
I want that if no value is passed onto an insertion, it should enter a default value of either completely blank ...
- 1,845
16
votes
4
answers
3k
views
Decoupling Domain classes from Django Model Classes
So I have completed my OO analysis and design of a web application that I am building and am now getting into implementation. Design decisions have been made to implement the system using Python and ...
- 249
16
votes
6
answers
14k
views
Model limit_choices_to={'user': user}
I went to all the documentation, also I went to the IRC channel (BTW a great community) and they told me that is not possible to create a model and limit choices in a field where the 'current user' is ...
- 1,090
15
votes
1
answer
23k
views
How to select QTableView row with one click
When one of the QTableView's QModelIndex is clicked I want to select an entire row of the same-row-indexes.
To accomplish this I connect QTableView's clicked signal to a custom viewClicked() method ...
- 18.7k
15
votes
3
answers
15k
views
Conditionally Require Only One Field In Django Model Form
Anyway to make a field conditionally required based on whether or not another field in the same form has been filled out?
If field1 has no data, but field2 does
form is valid.
If field1 has no ...
- 3,493
15
votes
5
answers
15k
views
Django DateTimeField auto_now_add not working
In one of the model i have set one timestamp field as follows:
created_datetime = models.DateTimeField(auto_now_add = True)
While in shell i am able to create a obj and save it, however in my ...
- 856
15
votes
1
answer
7k
views
How to move model to the other section in Django's site admin
Is it possible to move default Groups model from 'Authentication and Authoriation' section (on the Django admin site) to custom one and how to achieve that?
Let's start from the beginning in the ...
- 2,825