JSONField

Basic Usage

To use the JSON field:

from django.db import models
from django_postgres_extensions.models.fields import JSONField

class Product(models.Model):
    description = JSONField(null=True, blank=True)

Individual keys

• Get json values by key or key path:

  from django_postgres_extensions.models.expressions import Key
  obj = Product.objectsannotate(Key('description', 'Details')).get()
  obj = Product.objects.annotate(Key('description', 'Details__Rating')).get()
  obj = Product.objects.annotate(Key('description', 'Tags__1')).get()
  

• Update JSON Field by specific keys, leaving any others untouched:

  Product.objects.update(description__ = {'Industry': 'Movie', 'Popularity': 'Very Popular'})
  

• Delete JSONField by key or key path:

  Product.objects.update(description__del ='Details')
  Product.objects.update(description__del = 'Details__Release')
  Product.objects.update(description__del='Tags__1')
  

Database functions

Various database functions are included for interacting with JSONFields:

• JSONBSet: updates individual keys in the JSONField without modifying the others.
• JSONBArrayLength: returns the length of a JSONField who’s parent object is an array.

Check the postgresql documentation for more information on these functions. These functions handle the arguments by converting them to the correct expressions automatically:

from django_postgres_extensions.models.functions import *
from psycopg2.extras import Json
obj = Product.objects.update(description = JSONBSet('description', ['Details', 'Genre'], Json('Heavy Metal'), True))
obj = Product.objects.update(description = JSONBSet('description', ['1', 'c'], Json('g')))
obj = Product.objects.queryset.annotate(tags_length=JSONBArrayLength('tags', 1)).get()

Use With NestedFormField

The same NestedFormField and NestedFormWidget referred in the HStore description can also be used with a JSON Field. To use it give the fields keyword argument:

details_fields = (
    NestedFormField(label='Brand', keys=('Name', 'Country')),
    forms.CharField(label='Type', max_length=25, required=False),
    SplitArrayField(label='Colours', base_field=forms.CharField(max_length=10, required=False), size=10),
)

class Product(models.Model):
   details = JSONField(fields=details_fields, blank=True, default={})

The field would look like: