I have several models with one-to-one relation. For example
class Task(models.Model):
initial_comment = models.OneToOneField('Comment')
# A pack of other fields
class Comment(models.Model)
body = RichTextField()
# A pack of other fields
I want to create "create view" based on form, that gives user ability to create task and initial comment there.
I can't use CreateView because it is based on only one model
I can't use ModelForm because it is based on only one model
I can create several forms, but I can't join them into one formset (forms are different)
I feel "inlineformset_factory" (InlineFormSet) should be used here, but I am not sure it suits best. Is there any 3rd party Django app to do that?
Sure I can create form myself, but I do not want to copy/paste all fields, their types, localized labels, validations and so on. I just want to list their names (like fields attibute).
I can also have 2 forms and support them everywhere and track dependencies manually (save comments first), like in How can create a model form in django with a one-to-one relation with another model , but I hope there has to be better solution.
If you wonder why do I need one-to-one: Comments are used heavily in other places and have different relations with different models.
The inline_formset factory is correct. There are no standard generic views for this, but there is a third party package with generic views to do what you are wanting. Its in the standard Django way of doing things.
https://github.com/AndrewIngram/django-extra-views
You probably want to use the CreateWithInlinesView for that.
Well, I found solution.
CreateWithInlinesView works perfectly with OneToOneField (after all, 1-to-1 is just a foreign key with constraint), but my main model here is Comment, not Task. So I should set Comment as model field in this view and Task as inline. It looks silly. I will create custom form or review my model structure.
Related
I'm building a dashboard app that I would like the user to be able to customize. One of these customizable options would be the ability to choose different types of graphs to display data. My research into the best way to do this would be to use a ManyToMany field within my dashboard model; however, ManyToMany fields only allow 1 model--not multiple according to the docs:
A many-to-many relationship. Requires a positional argument: the class to which the model is related, which works exactly the same as it does for ForeignKey, including recursive and lazy relationships.
More research brought me to this SO post which recommended to create an intermediary 'ABCDRel' model that has foreign keys to each of the other models and emulate the behavior I'm looking for. The problem with that is I get this: as compared to what I'm looking for in this:
I use the admin page here to give a clearer picture of what I'm looking for.
Here's the intermediary I made according to the SO post above:
class GraphRelations(models.Model):
heatmap = models.ForeignKey(Heatmap, on_delete=models.CASCADE, related_name='m2m')
bar = models.ForeignKey(Bar, on_delete=models.CASCADE, related_name='m2m')
And the ManyToMany field I have in my dashboard model:
graphs = models.ManyToManyField(GraphRelations)
The only other option I can think of would be to add a foreign key to each graph model I have and set an 'enabled' field within that graph model. However, that's not very extensible and I feel there are cleaner ways to do this.
Any pointers are helpful!
Basically, what I want is a field to be available if a condition is met, so something like this:
class ConditionalModel(models.Model):
product = models.ForeignKey(product, on_delete=models.CASCADE)
if category == "laptop":
cpu_model = models.CharField(max_length=200)
so if I were to go to the Django admin page and create an instance of the model and then choose "laptop" as the product from the drop-down list of existing "products", a new field would be available. I couldn't find anything about this in the documentation, so I'm wondering whether it's even possible.
What you are asking for is not "technically" possible. A model relates a database object, and under traditional SQL rules, this isn't possible. You could instead make that field optional, and then customize the admin page's functionality.
Another potential option, though I do not have much experience with it, would be to use a NoSQL database in the case where you don't want to store NULL values in your db.
I do not think it is possible because models defines databases tables so the column has to be present.
You can use the keyword blank=True to allow an object without this field.
Maybe you can customize the admin interface to hide the field in some cases.
You can't do that in models.
You can hide it in admin panel or you can make separate model for laptop.
Or you can make field blank=True
Making a field optional is not possible but you can use a generalized model called Product and two or more specialized ones called for example : ElectronicProduct that contains the field cpu_model and NonElectronicProduct, the two specialized models have to contain a OneToOneField to the Product model to ensure inheritance.
I've been searching a way to reproduce admin-actions behavior on my own tables using django-tables2. I haven't found any module to introduce this functionality to a ListView to derive from it and looking at ModelAdmin I see there are many methods implied on this.
Of course, I can add a form around my table to get the checkboxes and a submit button pointing to a view that works with the ids but I'm looging to get a combo to choose among different actions as in django-admin but also to have that 'actions' meta option to list some methods as the possible actions to perform.
I found django-actions which is still very young but also it introduces it's own page for operations and I just need to integrate functionality on my own model so I can connect some input type=select with the model actions.
Any comment is appreciated :)
There is no built-in solution for it. You have to implement your actions in your views and the functionality to your templates.
Add, edit and delete operations are very easy to implement in your views.py. This depends on your models, but you can trigger database manipulations from within your templates and keep the logic in your views.py.
You can also easily add a form to your templates as it is described in the docs:
# forms.py
from django.forms import ModelForm
from myapp.models import Article
# Create the form class.
class ArticleForm(ModelForm):
class Meta:
model = Article
fields = ['pub_date', 'headline', 'content', 'reporter']
model := Choose your model which you want to modify / add
fields := Select some fields from your model, which you want to show up in your form
This defines a form corresponding to your model, which can be used in your templates to modify or add an entity to your database.
I'm really really confused about how django handles database relationships.
Originally I had an article model that contained a simple IntegerField for article_views, recently I'm trying to expand the definition of a article_view to contain it's own fields so I created a model for it. (IP, SESSION KEY etc..)
I'm at a bit of a loss regarding how to make the relationship, to me it makes the most sense to have a one-to-many field inside the article model, because an article can have many different views, but a view can only be part of one article.
all the implementations I'm seeing have this set up in a really weird reverse manner, what gives?
Unfortunately Django does not have a One-to-Many field. This is achieved by creating a ForeignKey on in this case the ArticleView model. When you want to easily access the article views in your template you can set the related_name on the ForeignKey.
class Article(models.Model):
# Article definition
class ArticleView(models.Model):
article = models.ForeignKey(Article, related_name='views')
In the template you can now use article.views.count() to get the number of views coupled to an account.
Please note that this creates a database query for each count you want. It would probably be better to have a queryset with annotate: Article.objects.annotate(num_views=Count('views'))
We have a django application that is, at its core, a series of webpages with Forms which our users fill out in order. (We'll call the particular series of pages with forms on them a "flow".)
We will be white-labeling this application for a Partner -- the Partner will want to add some fields and even add some webpages with their own new Forms. This may result in a new order in which the Forms are filled out. (A new "flow", in addition to changes to existing Forms/Models or new Forms/Models.)
What is the best way to extend our existing, simple Forms-and-Models structure to use different Forms and Models depending on the running instance of the app (e.g. an environment variable)? Some things we thought about:
implement something like get_user_model for every Model and Form use in the app, which would look at the current environment
implement a more generic key-value store so that we're not bound by the current implementation's field types (i.e., have the data field name be part of the data as well)
a data model which tracks this particular environment's "flow" and which models it needs to use
subclass existing Models and Forms for each new white-label implementation
Model Field injection may be what you are looking for, take a look of this article
The approach boils down to three concepts:
Dynamically adding fields to model classes Ensuring Django’s model
system respects the new fields
Getting the load ordering correct for the above to work
Mezzanine has done a beautiful job implementing this model field injection with dynamic extra models via EXTRA_MODEL_FIELDS