PostgreSQL specific model fieldsLink para este cabeçalho
All of these fields are available from the django.contrib.postgres.fields
module.
Indexing these fieldsLink para este cabeçalho
Index and Field.db_index both create a
B-tree index, which isn’t particularly helpful when querying complex data types.
Indexes such as GinIndex and
GistIndex are better suited, though
the index choice is dependent on the queries that you’re using. Generally, GiST
may be a good choice for the range fields and
HStoreField, and GIN may be helpful for ArrayField and
JSONField.
ArrayFieldLink para este cabeçalho
- class ArrayField(base_field, size=None, **options)Link para esta definição
A field for storing lists of data. Most field types can be used, you simply pass another field instance as the
base_field. You may also specify asize.ArrayFieldcan be nested to store multi-dimensional arrays.If you give the field a
default, ensure it’s a callable such aslist(for an empty default) or a callable that returns a list (such as a function). Incorrectly usingdefault=[]creates a mutable default that is shared between all instances ofArrayField.- base_fieldLink para esta definição
This is a required argument.
Specifies the underlying data type and behavior for the array. It should be an instance of a subclass of
Field. For example, it could be anIntegerFieldor aCharField. Most field types are permitted, with the exception of those handling relational data (ForeignKey,OneToOneFieldandManyToManyField).It is possible to nest array fields - you can specify an instance of
ArrayFieldas thebase_field. For example:from django.contrib.postgres.fields import ArrayField from django.db import models class ChessBoard(models.Model): board = ArrayField( ArrayField( models.CharField(max_length=10, blank=True), size=8, ), size=8, )Transformation of values between the database and the model, validation of data and configuration, and serialization are all delegated to the underlying base field.
- sizeLink para esta definição
This is an optional argument.
If passed, the array will have a maximum size as specified. This will be passed to the database, although PostgreSQL at present does not enforce the restriction.
Querying ArrayFieldLink para este cabeçalho
There are a number of custom lookups and transforms for ArrayField.
We will use the following example model:
from django.contrib.postgres.fields import ArrayField
from django.db import models
class Post(models.Model):
name = models.CharField(max_length=200)
tags = ArrayField(models.CharField(max_length=200), blank=True)
def __str__(self):
return self.name
containsLink para este cabeçalho
The contains lookup is overridden on ArrayField. The
returned objects will be those where the values passed are a subset of the
data. It uses the SQL operator @>. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.create(name='Third post', tags=['tutorial', 'django'])
>>> Post.objects.filter(tags__contains=['thoughts'])
<QuerySet [<Post: First post>, <Post: Second post>]>
>>> Post.objects.filter(tags__contains=['django'])
<QuerySet [<Post: First post>, <Post: Third post>]>
>>> Post.objects.filter(tags__contains=['django', 'thoughts'])
<QuerySet [<Post: First post>]>
contained_byLink para este cabeçalho
This is the inverse of the contains lookup -
the objects returned will be those where the data is a subset of the values
passed. It uses the SQL operator <@. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.create(name='Third post', tags=['tutorial', 'django'])
>>> Post.objects.filter(tags__contained_by=['thoughts', 'django'])
<QuerySet [<Post: First post>, <Post: Second post>]>
>>> Post.objects.filter(tags__contained_by=['thoughts', 'django', 'tutorial'])
<QuerySet [<Post: First post>, <Post: Second post>, <Post: Third post>]>
overlapLink para este cabeçalho
Returns objects where the data shares any results with the values passed. Uses
the SQL operator &&. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.create(name='Third post', tags=['tutorial', 'django'])
>>> Post.objects.filter(tags__overlap=['thoughts'])
<QuerySet [<Post: First post>, <Post: Second post>]>
>>> Post.objects.filter(tags__overlap=['thoughts', 'tutorial'])
<QuerySet [<Post: First post>, <Post: Second post>, <Post: Third post>]>
lenLink para este cabeçalho
Returns the length of the array. The lookups available afterwards are those
available for IntegerField. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.filter(tags__len=1)
<QuerySet [<Post: Second post>]>
Index transformsLink para este cabeçalho
Index transforms index into the array. Any non-negative integer can be used.
There are no errors if it exceeds the size of the
array. The lookups available after the transform are those from the
base_field. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.filter(tags__0='thoughts')
<QuerySet [<Post: First post>, <Post: Second post>]>
>>> Post.objects.filter(tags__1__iexact='Django')
<QuerySet [<Post: First post>]>
>>> Post.objects.filter(tags__276='javascript')
<QuerySet []>
Slice transformsLink para este cabeçalho
Slice transforms take a slice of the array. Any two non-negative integers can be used, separated by a single underscore. The lookups available after the transform do not change. For example:
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
>>> Post.objects.create(name='Third post', tags=['django', 'python', 'thoughts'])
>>> Post.objects.filter(tags__0_1=['thoughts'])
<QuerySet [<Post: First post>, <Post: Second post>]>
>>> Post.objects.filter(tags__0_2__contains=['thoughts'])
<QuerySet [<Post: First post>, <Post: Second post>]>
CIText fieldsLink para este cabeçalho
- class CIText(**options)Link para esta definição
A mixin to create case-insensitive text fields backed by the citext type. Read about the performance considerations prior to using it.
To use
citext, use theCITextExtensionoperation to setup the citext extension in PostgreSQL before the firstCreateModelmigration operation.Several fields that use the mixin are provided:
- class CICharField(**options)Link para esta definição
- class CIEmailField(**options)Link para esta definição
- class CITextField(**options)Link para esta definição
These fields subclass
CharField,EmailField, andTextField, respectively.max_lengthwon’t be enforced in the database sincecitextbehaves similar to PostgreSQL’stexttype.
HStoreFieldLink para este cabeçalho
- class HStoreField(**options)Link para esta definição
A field for storing key-value pairs. The Python data type used is a
dict. Keys must be strings, and values may be either strings or nulls (Nonein Python).To use this field, you’ll need to:
Add
'django.contrib.postgres'in yourINSTALLED_APPS.Setup the hstore extension in PostgreSQL.
You’ll see an error like
can't adapt type 'dict'if you skip the first step, ortype "hstore" does not existif you skip the second.
Querying HStoreFieldLink para este cabeçalho
In addition to the ability to query by key, there are a number of custom
lookups available for HStoreField.
We will use the following example model:
from django.contrib.postgres.fields import HStoreField
from django.db import models
class Dog(models.Model):
name = models.CharField(max_length=200)
data = HStoreField()
def __str__(self):
return self.name
Key lookupsLink para este cabeçalho
To query based on a given key, you simply use that key as the lookup name:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie'})
>>> Dog.objects.filter(data__breed='collie')
<QuerySet [<Dog: Meg>]>
You can chain other lookups after key lookups:
>>> Dog.objects.filter(data__breed__contains='l')
<QuerySet [<Dog: Rufus>, <Dog: Meg>]>
If the key you wish to query by clashes with the name of another lookup, you
need to use the hstorefield.contains lookup instead.
containsLink para este cabeçalho
The contains lookup is overridden on
HStoreField. The returned objects are
those where the given dict of key-value pairs are all contained in the
field. It uses the SQL operator @>. For example:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.create(name='Fred', data={})
>>> Dog.objects.filter(data__contains={'owner': 'Bob'})
<QuerySet [<Dog: Rufus>, <Dog: Meg>]>
>>> Dog.objects.filter(data__contains={'breed': 'collie'})
<QuerySet [<Dog: Meg>]>
contained_byLink para este cabeçalho
This is the inverse of the contains lookup -
the objects returned will be those where the key-value pairs on the object are
a subset of those in the value passed. It uses the SQL operator <@. For
example:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.create(name='Fred', data={})
>>> Dog.objects.filter(data__contained_by={'breed': 'collie', 'owner': 'Bob'})
<QuerySet [<Dog: Meg>, <Dog: Fred>]>
>>> Dog.objects.filter(data__contained_by={'breed': 'collie'})
<QuerySet [<Dog: Fred>]>
has_keyLink para este cabeçalho
Returns objects where the given key is in the data. Uses the SQL operator
?. For example:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.filter(data__has_key='owner')
<QuerySet [<Dog: Meg>]>
has_any_keysLink para este cabeçalho
Returns objects where any of the given keys are in the data. Uses the SQL
operator ?|. For example:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'owner': 'Bob'})
>>> Dog.objects.create(name='Fred', data={})
>>> Dog.objects.filter(data__has_any_keys=['owner', 'breed'])
<QuerySet [<Dog: Rufus>, <Dog: Meg>]>
has_keysLink para este cabeçalho
Returns objects where all of the given keys are in the data. Uses the SQL operator
?&. For example:
>>> Dog.objects.create(name='Rufus', data={})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.filter(data__has_keys=['breed', 'owner'])
<QuerySet [<Dog: Meg>]>
keysLink para este cabeçalho
Returns objects where the array of keys is the given value. Note that the order
is not guaranteed to be reliable, so this transform is mainly useful for using
in conjunction with lookups on
ArrayField. Uses the SQL function
akeys(). For example:
>>> Dog.objects.create(name='Rufus', data={'toy': 'bone'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.filter(data__keys__overlap=['breed', 'toy'])
<QuerySet [<Dog: Rufus>, <Dog: Meg>]>
valuesLink para este cabeçalho
Returns objects where the array of values is the given value. Note that the
order is not guaranteed to be reliable, so this transform is mainly useful for
using in conjunction with lookups on
ArrayField. Uses the SQL function
avalues(). For example:
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
>>> Dog.objects.filter(data__values__contains=['collie'])
<QuerySet [<Dog: Meg>]>
JSONFieldLink para este cabeçalho
- class JSONField(encoder=None, **options)Link para esta definição
A field for storing JSON encoded data. In Python the data is represented in its Python native format: dictionaries, lists, strings, numbers, booleans and
None.- encoderLink para esta definição
An optional JSON-encoding class to serialize data types not supported by the standard JSON serializer (
datetime,uuid, etc.). For example, you can use theDjangoJSONEncoderclass or any otherjson.JSONEncodersubclass.When the value is retrieved from the database, it will be in the format chosen by the custom encoder (most often a string), so you’ll need to take extra steps to convert the value back to the initial data type (
Model.from_db()andField.from_db_value()are two possible hooks for that purpose). Your deserialization may need to account for the fact that you can’t be certain of the input type. For example, you run the risk of returning adatetimethat was actually a string that just happened to be in the same format chosen fordatetimes.
If you give the field a
default, ensure it’s a callable such asdict(for an empty default) or a callable that returns a dict (such as a function). Incorrectly usingdefault={}creates a mutable default that is shared between all instances ofJSONField.
Querying JSONFieldLink para este cabeçalho
We will use the following example model:
from django.contrib.postgres.fields import JSONField
from django.db import models
class Dog(models.Model):
name = models.CharField(max_length=200)
data = JSONField()
def __str__(self):
return self.name
Key, index, and path lookupsLink para este cabeçalho
To query based on a given dictionary key, simply use that key as the lookup name:
>>> Dog.objects.create(name='Rufus', data={
... 'breed': 'labrador',
... 'owner': {
... 'name': 'Bob',
... 'other_pets': [{
... 'name': 'Fishy',
... }],
... },
... })
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': None})
>>> Dog.objects.filter(data__breed='collie')
<QuerySet [<Dog: Meg>]>
Multiple keys can be chained together to form a path lookup:
>>> Dog.objects.filter(data__owner__name='Bob')
<QuerySet [<Dog: Rufus>]>
If the key is an integer, it will be interpreted as an index lookup in an array:
>>> Dog.objects.filter(data__owner__other_pets__0__name='Fishy')
<QuerySet [<Dog: Rufus>]>
If the key you wish to query by clashes with the name of another lookup, use
the jsonfield.contains lookup instead.
If only one key or index is used, the SQL operator -> is used. If multiple
operators are used then the #> operator is used.
To query for null in JSON data, use None as a value:
>>> Dog.objects.filter(data__owner=None)
<QuerySet [<Dog: Meg>]>
To query for missing keys, use the isnull lookup:
>>> Dog.objects.create(name='Shep', data={'breed': 'collie'})
>>> Dog.objects.filter(data__owner__isnull=True)
<QuerySet [<Dog: Shep>]>
Containment and key operationsLink para este cabeçalho
JSONField shares lookups relating to
containment and keys with HStoreField.
contains(accepts any JSON rather than just a dictionary of strings)contained_by(accepts any JSON rather than just a dictionary of strings)
Range FieldsLink para este cabeçalho
There are five range field types, corresponding to the built-in range types in PostgreSQL. These fields are used to store a range of values; for example the start and end timestamps of an event, or the range of ages an activity is suitable for.
All of the range fields translate to psycopg2 Range objects in Python, but also accept tuples as input if no bounds
information is necessary. The default is lower bound included, upper bound
excluded; that is, [).
IntegerRangeFieldLink para este cabeçalho
- class IntegerRangeField(**options)Link para esta definição
Stores a range of integers. Based on an
IntegerField. Represented by anint4rangein the database and aNumericRangein Python.Regardless of the bounds specified when saving the data, PostgreSQL always returns a range in a canonical form that includes the lower bound and excludes the upper bound; that is
[).
BigIntegerRangeFieldLink para este cabeçalho
- class BigIntegerRangeField(**options)Link para esta definição
Stores a range of large integers. Based on a
BigIntegerField. Represented by anint8rangein the database and aNumericRangein Python.Regardless of the bounds specified when saving the data, PostgreSQL always returns a range in a canonical form that includes the lower bound and excludes the upper bound; that is
[).
FloatRangeFieldLink para este cabeçalho
- class FloatRangeField(**options)Link para esta definição
Stores a range of floating point values. Based on a
FloatField. Represented by anumrangein the database and aNumericRangein Python.
DateTimeRangeFieldLink para este cabeçalho
- class DateTimeRangeField(**options)Link para esta definição
Stores a range of timestamps. Based on a
DateTimeField. Represented by atstzrangein the database and aDateTimeTZRangein Python.
DateRangeFieldLink para este cabeçalho
- class DateRangeField(**options)Link para esta definição
Stores a range of dates. Based on a
DateField. Represented by adaterangein the database and aDateRangein Python.Regardless of the bounds specified when saving the data, PostgreSQL always returns a range in a canonical form that includes the lower bound and excludes the upper bound; that is
[).
Querying Range FieldsLink para este cabeçalho
There are a number of custom lookups and transforms for range fields. They are available on all the above fields, but we will use the following example model:
from django.contrib.postgres.fields import IntegerRangeField
from django.db import models
class Event(models.Model):
name = models.CharField(max_length=200)
ages = IntegerRangeField()
start = models.DateTimeField()
def __str__(self):
return self.name
We will also use the following example objects:
>>> import datetime
>>> from django.utils import timezone
>>> now = timezone.now()
>>> Event.objects.create(name='Soft play', ages=(0, 10), start=now)
>>> Event.objects.create(name='Pub trip', ages=(21, None), start=now - datetime.timedelta(days=1))
and NumericRange:
>>> from psycopg2.extras import NumericRange
Containment functionsLink para este cabeçalho
As with other PostgreSQL fields, there are three standard containment
operators: contains, contained_by and overlap, using the SQL
operators @>, <@, and && respectively.
containsLink para este cabeçalho
>>> Event.objects.filter(ages__contains=NumericRange(4, 5))
<QuerySet [<Event: Soft play>]>
contained_byLink para este cabeçalho
>>> Event.objects.filter(ages__contained_by=NumericRange(0, 15))
<QuerySet [<Event: Soft play>]>
The contained_by lookup is also available on the non-range field types:
IntegerField,
BigIntegerField,
FloatField, DateField,
and DateTimeField. For example:
>>> from psycopg2.extras import DateTimeTZRange
>>> Event.objects.filter(start__contained_by=DateTimeTZRange(
... timezone.now() - datetime.timedelta(hours=1),
... timezone.now() + datetime.timedelta(hours=1),
... )
<QuerySet [<Event: Soft play>]>
overlapLink para este cabeçalho
>>> Event.objects.filter(ages__overlap=NumericRange(8, 12))
<QuerySet [<Event: Soft play>]>
Comparison functionsLink para este cabeçalho
Range fields support the standard lookups: lt, gt,
lte and gte. These are not particularly helpful - they
compare the lower bounds first and then the upper bounds only if necessary.
This is also the strategy used to order by a range field. It is better to use
the specific range comparison operators.
fully_ltLink para este cabeçalho
The returned ranges are strictly less than the passed range. In other words, all the points in the returned range are less than all those in the passed range.
>>> Event.objects.filter(ages__fully_lt=NumericRange(11, 15))
<QuerySet [<Event: Soft play>]>
fully_gtLink para este cabeçalho
The returned ranges are strictly greater than the passed range. In other words, the all the points in the returned range are greater than all those in the passed range.
>>> Event.objects.filter(ages__fully_gt=NumericRange(11, 15))
<QuerySet [<Event: Pub trip>]>
not_ltLink para este cabeçalho
The returned ranges do not contain any points less than the passed range, that is the lower bound of the returned range is at least the lower bound of the passed range.
>>> Event.objects.filter(ages__not_lt=NumericRange(0, 15))
<QuerySet [<Event: Soft play>, <Event: Pub trip>]>
not_gtLink para este cabeçalho
The returned ranges do not contain any points greater than the passed range, that is the upper bound of the returned range is at most the upper bound of the passed range.
>>> Event.objects.filter(ages__not_gt=NumericRange(3, 10))
<QuerySet [<Event: Soft play>]>
adjacent_toLink para este cabeçalho
The returned ranges share a bound with the passed range.
>>> Event.objects.filter(ages__adjacent_to=NumericRange(10, 21))
<QuerySet [<Event: Soft play>, <Event: Pub trip>]>
Querying using the boundsLink para este cabeçalho
There are three transforms available for use in queries. You can extract the lower or upper bound, or query based on emptiness.
startswithLink para este cabeçalho
Returned objects have the given lower bound. Can be chained to valid lookups for the base field.
>>> Event.objects.filter(ages__startswith=21)
<QuerySet [<Event: Pub trip>]>
endswithLink para este cabeçalho
Returned objects have the given upper bound. Can be chained to valid lookups for the base field.
>>> Event.objects.filter(ages__endswith=10)
<QuerySet [<Event: Soft play>]>
isemptyLink para este cabeçalho
Returned objects are empty ranges. Can be chained to valid lookups for a
BooleanField.
>>> Event.objects.filter(ages__isempty=True)
<QuerySet []>
Defining your own range typesLink para este cabeçalho
PostgreSQL allows the definition of custom range types. Django’s model and form
field implementations use base classes below, and psycopg2 provides a
register_range() to allow use of custom range
types.
- class RangeField(**options)Link para esta definição
Base class for model range fields.
- base_fieldLink para esta definição
The model field class to use.
- range_typeLink para esta definição
The psycopg2 range type to use.
- form_fieldLink para esta definição
The form field class to use. Should be a subclass of
django.contrib.postgres.forms.BaseRangeField.
- class django.contrib.postgres.forms.BaseRangeFieldLink para esta definição
Base class for form range fields.
- base_fieldLink para esta definição
The form field to use.
- range_typeLink para esta definição
The psycopg2 range type to use.