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Here is the source: https://docs.djangoproject.com/en/1.8/topics/db/queries/
At the beginning, let's look at the models.py field:
from django.db import models
class Blog(models.Model):
name = models.CharField(max_length=100)
tagline = models.TextField()
def __str__(self): # __unicode__ on Python 2
return self.name
class Author(models.Model):
name = models.CharField(max_length=50)
email = models.EmailField()
def __str__(self): # __unicode__ on Python 2
return self.name
class Entry(models.Model):
blog = models.ForeignKey(Blog)
headline = models.CharField(max_length=255)
body_text = models.TextField()
pub_date = models.DateField()
mod_date = models.DateField()
authors = models.ManyToManyField(Author)
n_comments = models.IntegerField()
n_pingbacks = models.IntegerField()
rating = models.IntegerField()
def __str__(self): # __unicode__ on Python 2
return self.headline
This is how, a row or an object is created of Blog type:
>>> from blog.models import Blog
>>> b = Blog(name='Beatles Blog', tagline='All the latest Beatles news.')
>>> b.save()
My question is how to update blog column/attribute of Entry object (which stores Foreign Key in relation to Blog) with the entry I created in Blog class?
885
Use update_fields in save() If you would like to explicitly mention only those columns that you want to be updated, you can do so using the update_fields parameter while calling the save() method. You can also choose to update multiple columns by passing more field names in the update_fields list.
As stated in the documentation, you will need to write your own create() and update() methods in your serializer to support writable nested data. You will also need to explicitly add the status field instead of using the depth argument otherwise I believe it won't be automatically added to validated_data .
To answer your question, with the new migration introduced in Django 1.7, in order to add a new field to a model you can simply add that field to your model and initialize migrations with ./manage.py makemigrations and then run ./manage.py migrate and the new field will be added to your DB.
Django automatically creates an index for all models. ForeignKey columns. From Django documentation: A database index is automatically created on the ForeignKey .
First get the Blog object and then pass it to Entry.
b=Blog.objects.get(name='Beatles Blog', tagline='All the latest Beatles news.')
e=Entry(blog=b,headline='some headline',body_text='text here',....)
e.save()
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