Questions tagged [multi-table-inheritance]
52 questions
1
vote
1 answer
Rails polymorphic association with multiple foreign keys and database constraints
I've been playing with Multi-Table inheritance and database constraints. I know that Rails philosophy is to handle constraints in the code and not in the database but I'd like to do both. I also know about polymorphic associations but they don't let…
karellm
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1
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1 answer
'Can't mass-assign protected attributes' when implementing Multiple Table Inheritance with nested forms
HI I am trying to implement the MTI in my application. I have a Person Model and 2 models inheriting from it: Client and TeamMember. When creating a Team Member I want to save to to database vallues for both person (first and last name, email etc)…
evoo
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0 answers
Django 1.5 select_related defer with multi table inheritance
EDIT:
I fixed a few typos below
I added a zip file to a small app to demonstrate this problem here. You can download it and run python manage.py testselectrelateddefer after you syncdb and migrate.
I added a couple of observations below
I fix I am…
nlhma
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- 3
1
vote
2 answers
how to conditionally save a form using django multi table inheritance
I have the following form:
class PlaceForm(forms.ModelForm):
class Meta:
model = Place
I have the following models:
class Place(models.Model):
customer = models.ForeignKey(Customer)
name = models.CharField(max_length=50)
…
Atma
- 29,141
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1
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1 answer
How to allow user to edit post with Django?
In my blog I decided to allow users to edit posts (I am using Django), but I am not sure what is the right implementation for my models to do that. Is a good idea to use multi-table inheritance as my code below? I also want to keep track of all the…
Pompeyo
- 1,459
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1
vote
2 answers
Multiple level Inheritance Mapping with doctrine 2
I have three entities which are "Addressable" (can have an Address):
Delivery Points
Customers
Distribution Centers
Every Addressable entity also is Geolocatable (has latitude and longitude), but i have entities that are Geolocatable but not…
Felipe Zavan
- 1,654
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1
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1 answer
Multiple Table Inheritance, columns not accessible from sub class
UPDATE:
changing table_name to self.table_name = seems to have convinced rails to use the correct table.
I am, however, now getting these weird errors
Mysql2::Error: Unknown column 'templates.deleted_at' in 'where clause': SELECT `objekts`.*…
NullVoxPopuli
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- 352
0
votes
1 answer
Add Django model parent class to an existing "child" model for multi-table inheritance
I would like to add a new parent class to an existing model, which inherits from the same "super" parent class. Example of initial condition:
from django.db import models
class Ticket(PolymorphicModel):
name = models.CharField(max_length=50)
…
jenesaisquoi
- 35
- 4
0
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1 answer
Elegantly spread single Django model across multiple tables?
There's plenty of document and discussion for having multiple models share fields in a parent class/table using "concrete" or "multi-table" inheritance:
class Place(models.Model):
...
class Restaurant(Place):
...
However, I can't find much…
odigity
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2 answers
Extend model in Ruby on Rails for RESTful api app
As a part of a project we got an UML diagram to implement. Now I'm at the part of OOP, but I'm not sure how to implement that in Ruby.
Every Task is a Chore or Homework, as I understand it must be multi table inheritance(MTI).
I'm not sure how to…
Efim Risberg
- 1
- 1
0
votes
1 answer
How do you set up MTI in Rails with a polymorphic belongs_to association?
In an effort to create a Short, Self Contained, Correct (Compilable), Example, imagine that I want to do the following.
I have a blog website. There are two types of posts, TextPost and LinkPost. There are also two types of users, User and Guest. I…
Adam Zerner
- 17,797
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0
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0 answers
Empty QuerySet for Django Multi-Table Inheritance Subclass
I have the following models:
APP 1:
class User(AbstractBaseUser):
# custom fields etc
# NOT ABSTRACT
APP 2:
class SecondaryUser(User):
# other custom fields
When I do SecondaryUser.objects.create(...) I get an instance as…
RHSmith159
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0
votes
0 answers
Query optimisation for FK association on inherited model from the base model
I have users who create (or receive) transactions. The transaction hierarchy I have is a multi-table inheritance, with Transaction as the base model containing the common fields between all transaction types, such as User (FK), amount, etc. I have…
Maps
- 135
- 10
0
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1 answer
How should I model different document types?
I am building a Ruby On Rails API that helps manage construction documents -- there are a number of different types of documents that all have different fields, so I currently have a model for each.
However, I also would like the ability to refer to…
Aaron Cohen
- 132
- 8
0
votes
1 answer
Is polymorphic query of base Model in case of Multi-table inheritance in Django possible?
I.e. we have
class Place(models.Model):...
class Restaurant(Place):...
class Cafe(Place):...
I'd like to query Place somehow:
q = Place.objects.all() # how?
but for q[x] i'd like to have not Place class instance, but Restaurant or Cafe instead…
john.don83
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