Field options
The following arguments are available to all field types. All are optional.
null
- Field.null
If True
, Django will store empty values as NULL
in the database. Default is False
.
Avoid using null on string-based fields such as CharField and TextField. If a string-based field has null=True
, that means it has two possible values for “no data”: NULL
, and the empty string. In most cases, it’s redundant to have two possible values for “no data;” the Django convention is to use the empty string, not NULL
. One exception is when a CharField has both unique=True
and blank=True
set. In this situation, null=True
is required to avoid unique constraint violations when saving multiple objects with blank values.
For both string-based and non-string-based fields, you will also need to set blank=True
if you wish to permit empty values in forms, as the null parameter only affects database storage (see blank).
Note
When using the Oracle database backend, the value NULL
will be stored to denote the empty string regardless of this attribute.
blank
- Field.blank
If True
, the field is allowed to be blank. Default is False
.
Note that this is different than null. null is purely database-related, whereas blank is validation-related. If a field has blank=True
, form validation will allow entry of an empty value. If a field has blank=False
, the field will be required.
choices
- Field.choices
A sequence consisting itself of iterables of exactly two items (e.g. [(A, B), (A, B) ...]
) to use as choices for this field. If choices are given, they’re enforced by model validation and the default form widget will be a select box with these choices instead of the standard text field.
The first element in each tuple is the actual value to be set on the model, and the second element is the human-readable name. For example:
YEAR_IN_SCHOOL_CHOICES = [
('FR', 'Freshman'),
('SO', 'Sophomore'),
('JR', 'Junior'),
('SR', 'Senior'),
('GR', 'Graduate'),
]
Generally, it’s best to define choices inside a model class, and to define a suitably-named constant for each value:
from django.db import models
class Student(models.Model):
FRESHMAN = 'FR'
SOPHOMORE = 'SO'
JUNIOR = 'JR'
SENIOR = 'SR'
GRADUATE = 'GR'
YEAR_IN_SCHOOL_CHOICES = [
(FRESHMAN, 'Freshman'),
(SOPHOMORE, 'Sophomore'),
(JUNIOR, 'Junior'),
(SENIOR, 'Senior'),
(GRADUATE, 'Graduate'),
]
year_in_school = models.CharField(
max_length=2,
choices=YEAR_IN_SCHOOL_CHOICES,
default=FRESHMAN,
)
def is_upperclass(self):
return self.year_in_school in {self.JUNIOR, self.SENIOR}
Though you can define a choices list outside of a model class and then refer to it, defining the choices and names for each choice inside the model class keeps all of that information with the class that uses it, and helps reference the choices (e.g, Student.SOPHOMORE
will work anywhere that the Student
model has been imported).
You can also collect your available choices into named groups that can be used for organizational purposes:
MEDIA_CHOICES = [
('Audio', (
('vinyl', 'Vinyl'),
('cd', 'CD'),
)
),
('Video', (
('vhs', 'VHS Tape'),
('dvd', 'DVD'),
)
),
('unknown', 'Unknown'),
]
The first element in each tuple is the name to apply to the group. The second element is an iterable of 2-tuples, with each 2-tuple containing a value and a human-readable name for an option. Grouped options may be combined with ungrouped options within a single list (such as the 'unknown'
option in this example).
For each model field that has choices set, Django will add a method to retrieve the human-readable name for the field’s current value. See get_FOO_display() in the database API documentation.
Note that choices can be any sequence object – not necessarily a list or tuple. This lets you construct choices dynamically. But if you find yourself hacking choices to be dynamic, you’re probably better off using a proper database table with a ForeignKey. choices is meant for static data that doesn’t change much, if ever.
Note
A new migration is created each time the order of choices
changes.
Unless blank=False is set on the field along with a default then a label containing "---------"
will be rendered with the select box. To override this behavior, add a tuple to choices
containing None
; e.g. (None, 'Your String For Display')
. Alternatively, you can use an empty string instead of None
where this makes sense - such as on a CharField.
Enumeration types
In addition, Django provides enumeration types that you can subclass to define choices in a concise way:
from django.utils.translation import gettext_lazy as _
class Student(models.Model):
class YearInSchool(models.TextChoices):
FRESHMAN = 'FR', _('Freshman')
SOPHOMORE = 'SO', _('Sophomore')
JUNIOR = 'JR', _('Junior')
SENIOR = 'SR', _('Senior')
GRADUATE = 'GR', _('Graduate')
year_in_school = models.CharField(
max_length=2,
choices=YearInSchool.choices,
default=YearInSchool.FRESHMAN,
)
def is_upperclass(self):
return self.year_in_school in {
self.YearInSchool.JUNIOR,
self.YearInSchool.SENIOR,
}
These work similar to enum
from Python’s standard library, but with some modifications:
- Enum member values are a tuple of arguments to use when constructing the concrete data type. Django supports adding an extra string value to the end of this tuple to be used as the human-readable name, or
label
. The label
can be a lazy translatable string. Thus, in most cases, the member value will be a (value, label)
two-tuple. See below for an example of subclassing choices using a more complex data type. If a tuple is not provided, or the last item is not a (lazy) string, the label
is automatically generated from the member name.
- A
.label
property is added on values, to return the human-readable name.
- A number of custom properties are added to the enumeration classes –
.choices
, .labels
, .values
, and .names
– to make it easier to access lists of those separate parts of the enumeration. Use .choices
as a suitable value to pass to choices in a field definition.
- The use of
enum.unique()
is enforced to ensure that values cannot be defined multiple times. This is unlikely to be expected in choices for a field.
Note that using YearInSchool.SENIOR
, YearInSchool['SENIOR']
, or YearInSchool('SR')
to access or lookup enum members work as expected, as do the .name
and .value
properties on the members.
If you don’t need to have the human-readable names translated, you can have them inferred from the member name (replacing underscores with spaces and using title-case):
>>> class Vehicle(models.TextChoices):
... CAR = 'C'
... TRUCK = 'T'
... JET_SKI = 'J'
...
>>> Vehicle.JET_SKI.label
'Jet Ski'
Since the case where the enum values need to be integers is extremely common, Django provides an IntegerChoices
class. For example:
class Card(models.Model):
class Suit(models.IntegerChoices):
DIAMOND = 1
SPADE = 2
HEART = 3
CLUB = 4
suit = models.IntegerField(choices=Suit.choices)
It is also possible to make use of the Enum Functional API with the caveat that labels are automatically generated as highlighted above:
>>> MedalType = models.TextChoices('MedalType', 'GOLD SILVER BRONZE')
>>> MedalType.choices
[('GOLD', 'Gold'), ('SILVER', 'Silver'), ('BRONZE', 'Bronze')]
>>> Place = models.IntegerChoices('Place', 'FIRST SECOND THIRD')
>>> Place.choices
[(1, 'First'), (2, 'Second'), (3, 'Third')]
If you require support for a concrete data type other than int
or str
, you can subclass Choices
and the required concrete data type, e.g. date
for use with DateField:
class MoonLandings(datetime.date, models.Choices):
APOLLO_11 = 1969, 7, 20, 'Apollo 11 (Eagle)'
APOLLO_12 = 1969, 11, 19, 'Apollo 12 (Intrepid)'
APOLLO_14 = 1971, 2, 5, 'Apollo 14 (Antares)'
APOLLO_15 = 1971, 7, 30, 'Apollo 15 (Falcon)'
APOLLO_16 = 1972, 4, 21, 'Apollo 16 (Orion)'
APOLLO_17 = 1972, 12, 11, 'Apollo 17 (Challenger)'
There are some additional caveats to be aware of:
Enumeration types do not support named groups.
Because an enumeration with a concrete data type requires all values to match the type, overriding the blank label cannot be achieved by creating a member with a value of None
. Instead, set the __empty__
attribute on the class:
class Answer(models.IntegerChoices):
NO = 0, _('No')
YES = 1, _('Yes')
__empty__ = _('(Unknown)')
New in version 3.0: The TextChoices
, IntegerChoices
, and Choices
classes were added.
db_column
- Field.db_column
The name of the database column to use for this field. If this isn’t given, Django will use the field’s name.
If your database column name is an SQL reserved word, or contains characters that aren’t allowed in Python variable names – notably, the hyphen – that’s OK. Django quotes column and table names behind the scenes.
db_index
- Field.db_index
If True
, a database index will be created for this field.
default
- Field.default
The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created.
The default can’t be a mutable object (model instance, list
, set
, etc.), as a reference to the same instance of that object would be used as the default value in all new model instances. Instead, wrap the desired default in a callable. For example, if you want to specify a default dict
for JSONField, use a function:
def contact_default():
return {"email": "[email protected]"}
contact_info = JSONField("ContactInfo", default=contact_default)
lambda
s can’t be used for field options like default
because they can’t be serialized by migrations. See that documentation for other caveats.
For fields like ForeignKey that map to model instances, defaults should be the value of the field they reference (pk
unless to_field is set) instead of model instances.
The default value is used when new model instances are created and a value isn’t provided for the field. When the field is a primary key, the default is also used when the field is set to None
.
editable
- Field.editable
If False
, the field will not be displayed in the admin or any other ModelForm. They are also skipped during model validation. Default is True
.
error_messages
- Field.error_messages
The error_messages
argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override.
Error message keys include null
, blank
, invalid
, invalid_choice
, unique
, and unique_for_date
. Additional error message keys are specified for each field in the Field types section below.
These error messages often don’t propagate to forms. See Considerations regarding model’s error_messages.
help_text
- Field.help_text
Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form.
Note that this value is not HTML-escaped in automatically-generated forms. This lets you include HTML in help_text if you so desire. For example:
help_text="Please use the following format: <em>YYYY-MM-DD</em>."
Alternatively you can use plain text and django.utils.html.escape() to escape any HTML special characters. Ensure that you escape any help text that may come from untrusted users to avoid a cross-site scripting attack.
primary_key
- Field.primary_key
If True
, this field is the primary key for the model.
If you don’t specify primary_key=True
for any field in your model, Django will automatically add an AutoField to hold the primary key, so you don’t need to set primary_key=True
on any of your fields unless you want to override the default primary-key behavior. For more, see Automatic primary key fields.
primary_key=True
implies null=False and unique=True. Only one primary key is allowed on an object.
The primary key field is read-only. If you change the value of the primary key on an existing object and then save it, a new object will be created alongside the old one.
unique
- Field.unique
If True
, this field must be unique throughout the table.
This is enforced at the database level and by model validation. If you try to save a model with a duplicate value in a unique field, a django.db.IntegrityError will be raised by the model’s save() method.
This option is valid on all field types except ManyToManyField and OneToOneField.
Note that when unique
is True
, you don’t need to specify db_index, because unique
implies the creation of an index.
unique_for_date
- Field.unique_for_date
Set this to the name of a DateField or DateTimeField to require that this field be unique for the value of the date field.
For example, if you have a field title
that has unique_for_date="pub_date"
, then Django wouldn’t allow the entry of two records with the same title
and pub_date
.
Note that if you set this to point to a DateTimeField, only the date portion of the field will be considered. Besides, when :setting:`USE_TZ` is True
, the check will be performed in the current time zone at the time the object gets saved.
This is enforced by Model.validate_unique() during model validation but not at the database level. If any unique_for_date constraint involves fields that are not part of a ModelForm (for example, if one of the fields is listed in exclude
or has editable=False), Model.validate_unique() will skip validation for that particular constraint.
unique_for_month
- Field.unique_for_month
Like unique_for_date, but requires the field to be unique with respect to the month.
verbose_name
- Field.verbose_name
A human-readable name for the field. If the verbose name isn’t given, Django will automatically create it using the field’s attribute name, converting underscores to spaces. See Verbose field names.
validators
- Field.validators
A list of validators to run for this field. See the validators documentation for more information.
Registering and fetching lookups
Field
implements the lookup registration API. The API can be used to customize which lookups are available for a field class, and how lookups are fetched from a field.
Field types
AutoField
- class AutoField(**options)
An IntegerField that automatically increments according to available IDs. You usually won’t need to use this directly; a primary key field will automatically be added to your model if you don’t specify otherwise. See Automatic primary key fields.
BigAutoField
- class BigAutoField(**options)
A 64-bit integer, much like an AutoField except that it is guaranteed to fit numbers from 1
to 9223372036854775807
.
BigIntegerField
- class BigIntegerField(**options)
A 64-bit integer, much like an IntegerField except that it is guaranteed to fit numbers from -9223372036854775808
to 9223372036854775807
. The default form widget for this field is a NumberInput.
BinaryField
- class BinaryField(max_length=None, **options)
A field to store raw binary data. It can be assigned bytes
, bytearray
, or memoryview
.
By default, BinaryField
sets editable to False
, in which case it can’t be included in a ModelForm.
BinaryField
has one extra optional argument:
- BinaryField.max_length
- The maximum length (in characters) of the field. The maximum length is enforced in Django’s validation using MaxLengthValidator.
Abusing BinaryField
Although you might think about storing files in the database, consider that it is bad design in 99% of the cases. This field is not a replacement for proper static files handling.
CharField
- class CharField(max_length=None, **options)
A string field, for small- to large-sized strings.
For large amounts of text, use TextField.
The default form widget for this field is a TextInput.
CharField has one extra required argument:
- CharField.max_length
- The maximum length (in characters) of the field. The max_length is enforced at the database level and in Django’s validation using MaxLengthValidator.
Note
If you are writing an application that must be portable to multiple database backends, you should be aware that there are restrictions on max_length
for some backends. Refer to the database backend notes for details.
DateField
- class DateField(auto_now=False, auto_now_add=False, **options)
A date, represented in Python by a datetime.date
instance. Has a few extra, optional arguments:
- DateField.auto_now
Automatically set the field to now every time the object is saved. Useful for “last-modified” timestamps. Note that the current date is always used; it’s not just a default value that you can override.
The field is only automatically updated when calling Model.save(). The field isn’t updated when making updates to other fields in other ways such as QuerySet.update(), though you can specify a custom value for the field in an update like that.
- DateField.auto_now_add
- Automatically set the field to now when the object is first created. Useful for creation of timestamps. Note that the current date is always used; it’s not just a default value that you can override. So even if you set a value for this field when creating the object, it will be ignored. If you want to be able to modify this field, set the following instead of
auto_now_add=True
:
- For DateField
The default form widget for this field is a DateInput. The admin adds a JavaScript calendar, and a shortcut for “Today”. Includes an additional invalid_date
error message key.
The options auto_now_add
, auto_now
, and default
are mutually exclusive. Any combination of these options will result in an error.
Note
As currently implemented, setting auto_now
or auto_now_add
to True
will cause the field to have editable=False
and blank=True
set.
Note
The auto_now
and auto_now_add
options will always use the date in the default timezone at the moment of creation or update. If you need something different, you may want to consider using your own callable default or overriding save()
instead of using auto_now
or auto_now_add
; or using a DateTimeField
instead of a DateField
and deciding how to handle the conversion from datetime to date at display time.
DateTimeField
- class DateTimeField(auto_now=False, auto_now_add=False, **options)
A date and time, represented in Python by a datetime.datetime
instance. Takes the same extra arguments as DateField.
The default form widget for this field is a single DateTimeInput. The admin uses two separate TextInput widgets with JavaScript shortcuts.
DecimalField
- class DecimalField(max_digits=None, decimal_places=None, **options)
A fixed-precision decimal number, represented in Python by a Decimal
instance. It validates the input using DecimalValidator.
Has two required arguments:
- DecimalField.max_digits
- The maximum number of digits allowed in the number. Note that this number must be greater than or equal to
decimal_places
.
- DecimalField.decimal_places
- The number of decimal places to store with the number.
For example, to store numbers up to 999
with a resolution of 2 decimal places, you’d use:
models.DecimalField(..., max_digits=5, decimal_places=2)
And to store numbers up to approximately one billion with a resolution of 10 decimal places:
models.DecimalField(..., max_digits=19, decimal_places=10)
The default form widget for this field is a NumberInput when localize is False
or TextInput otherwise.
Note
For more information about the differences between the FloatField and DecimalField classes, please see FloatField vs. DecimalField. You should also be aware of SQLite limitations of decimal fields.
DurationField
- class DurationField(**options)
A field for storing periods of time - modeled in Python by timedelta
. When used on PostgreSQL, the data type used is an interval
and on Oracle the data type is INTERVAL DAY(9) TO SECOND(6)
. Otherwise a bigint
of microseconds is used.
Note
Arithmetic with DurationField
works in most cases. However on all databases other than PostgreSQL, comparing the value of a DurationField
to arithmetic on DateTimeField
instances will not work as expected.
EmailField
- class EmailField(max_length=254, **options)
A CharField that checks that the value is a valid email address using EmailValidator.
FileField
- class FileField(upload_to=None, max_length=100, **options)
A file-upload field.
Note
The primary_key
argument isn’t supported and will raise an error if used.
Has two optional arguments:
- FileField.upload_to
This attribute provides a way of setting the upload directory and file name, and can be set in two ways. In both cases, the value is passed to the Storage.save() method.
If you specify a string value or a Path
, it may contain strftime()
formatting, which will be replaced by the date/time of the file upload (so that uploaded files don’t fill up the given directory). For example:
class MyModel(models.Model):
# file will be uploaded to MEDIA_ROOT/uploads
upload = models.FileField(upload_to='uploads/')
# or...
# file will be saved to MEDIA_ROOT/uploads/2015/01/30
upload = models.FileField(upload_to='uploads/%Y/%m/%d/')
If you are using the default FileSystemStorage, the string value will be appended to your :setting:`MEDIA_ROOT` path to form the location on the local filesystem where uploaded files will be stored. If you are using a different storage, check that storage’s documentation to see how it handles upload_to
.
upload_to
may also be a callable, such as a function. This will be called to obtain the upload path, including the filename. This callable must accept two arguments and return a Unix-style path (with forward slashes) to be passed along to the storage system. The two arguments are:
Argument
|
Description
|
instance
|
An instance of the model where the FileField is defined. More specifically, this is the particular instance where the current file is being attached.
In most cases, this object will not have been saved to the database yet, so if it uses the default AutoField , it might not yet have a value for its primary key field.
|
filename
|
The filename that was originally given to the file. This may or may not be taken into account when determining the final destination path.
|
For example:
def user_directory_path(instance, filename):
# file will be uploaded to MEDIA_ROOT/user_<id>/<filename>
return 'user_{0}/{1}'.format(instance.user.id, filename)
class MyModel(models.Model):
upload = models.FileField(upload_to=user_directory_path)
Changed in version 3.0: Support for pathlib.Path
was added.
- FileField.storage
A storage object, or a callable which returns a storage object. This handles the storage and retrieval of your files. See Managing files for details on how to provide this object.
Changed in version 3.1: The ability to provide a callable was added.
The default form widget for this field is a ClearableFileInput.
Using a FileField or an ImageField (see below) in a model takes a few steps:
- In your settings file, you’ll need to define :setting:`MEDIA_ROOT` as the full path to a directory where you’d like Django to store uploaded files. (For performance, these files are not stored in the database.) Define :setting:`MEDIA_URL` as the base public URL of that directory. Make sure that this directory is writable by the Web server’s user account.
- Add the FileField or ImageField to your model, defining the upload_to option to specify a subdirectory of :setting:`MEDIA_ROOT` to use for uploaded files.
- All that will be stored in your database is a path to the file (relative to :setting:`MEDIA_ROOT`). You’ll most likely want to use the convenience url attribute provided by Django. For example, if your ImageField is called
mug_shot
, you can get the absolute path to your image in a template with Template:Object.mug shot.url
.
For example, say your :setting:`MEDIA_ROOT` is set to '/home/media'
, and upload_to is set to 'photos/%Y/%m/%d'
. The '%Y/%m/%d'
part of upload_to is strftime()
formatting; '%Y'
is the four-digit year, '%m'
is the two-digit month and '%d'
is the two-digit day. If you upload a file on Jan. 15, 2007, it will be saved in the directory /home/media/photos/2007/01/15
.
If you wanted to retrieve the uploaded file’s on-disk filename, or the file’s size, you could use the name and size attributes respectively; for more information on the available attributes and methods, see the File class reference and the Managing files topic guide.
Note
The file is saved as part of saving the model in the database, so the actual file name used on disk cannot be relied on until after the model has been saved.
The uploaded file’s relative URL can be obtained using the url attribute. Internally, this calls the url() method of the underlying Storage class.
Note that whenever you deal with uploaded files, you should pay close attention to where you’re uploading them and what type of files they are, to avoid security holes. Validate all uploaded files so that you’re sure the files are what you think they are. For example, if you blindly let somebody upload files, without validation, to a directory that’s within your Web server’s document root, then somebody could upload a CGI or PHP script and execute that script by visiting its URL on your site. Don’t allow that.
Also note that even an uploaded HTML file, since it can be executed by the browser (though not by the server), can pose security threats that are equivalent to XSS or CSRF attacks.
FileField instances are created in your database as varchar
columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the max_length argument.
FileField and FieldFile
- class FieldFile
When you access a FileField on a model, you are given an instance of FieldFile as a proxy for accessing the underlying file.
The API of FieldFile mirrors that of File, with one key difference: The object wrapped by the class is not necessarily a wrapper around Python’s built-in file object. Instead, it is a wrapper around the result of the Storage.open() method, which may be a File object, or it may be a custom storage’s implementation of the File API.
In addition to the API inherited from File such as read()
and write()
, FieldFile includes several methods that can be used to interact with the underlying file:
Warning
Two methods of this class, save() and delete(), default to saving the model object of the associated FieldFile
in the database.
- FieldFile.name
The name of the file including the relative path from the root of the Storage of the associated FileField.
- FieldFile.path
A read-only property to access the file’s local filesystem path by calling the path() method of the underlying Storage class.
- FieldFile.size
The result of the underlying Storage.size() method.
- FieldFile.url
A read-only property to access the file’s relative URL by calling the url() method of the underlying Storage class.
- FieldFile.open(mode='rb')
Opens or reopens the file associated with this instance in the specified mode
. Unlike the standard Python open()
method, it doesn’t return a file descriptor.
Since the underlying file is opened implicitly when accessing it, it may be unnecessary to call this method except to reset the pointer to the underlying file or to change the mode
.
- FieldFile.close()
Behaves like the standard Python file.close()
method and closes the file associated with this instance.
- FieldFile.save(name, content, save=True)
This method takes a filename and file contents and passes them to the storage class for the field, then associates the stored file with the model field. If you want to manually associate file data with FileField instances on your model, the save()
method is used to persist that file data.
Takes two required arguments: name
which is the name of the file, and content
which is an object containing the file’s contents. The optional save
argument controls whether or not the model instance is saved after the file associated with this field has been altered. Defaults to True
.
Note that the content
argument should be an instance of django.core.files.File, not Python’s built-in file object. You can construct a File from an existing Python file object like this:
from django.core.files import File
# Open an existing file using Python's built-in open()
f = open('/path/to/hello.world')
myfile = File(f)
Or you can construct one from a Python string like this:
from django.core.files.base import ContentFile
myfile = ContentFile("hello world")
For more information, see Managing files.
- FieldFile.delete(save=True)
Deletes the file associated with this instance and clears all attributes on the field. Note: This method will close the file if it happens to be open when delete()
is called.
The optional save
argument controls whether or not the model instance is saved after the file associated with this field has been deleted. Defaults to True
.
Note that when a model is deleted, related files are not deleted. If you need to cleanup orphaned files, you’ll need to handle it yourself (for instance, with a custom management command that can be run manually or scheduled to run periodically via e.g. cron).
FilePathField
- class FilePathField(path=, match=None, recursive=False, allow_files=True, allow_folders=False, max_length=100, **options)
A CharField whose choices are limited to the filenames in a certain directory on the filesystem. Has some special arguments, of which the first is required:
- FilePathField.path
Required. The absolute filesystem path to a directory from which this FilePathField should get its choices. Example: "/home/images"
.
path
may also be a callable, such as a function to dynamically set the path at runtime. Example:
import os
from django.conf import settings
from django.db import models
def images_path():
return os.path.join(settings.LOCAL_FILE_DIR, 'images')
class MyModel(models.Model):
file = models.FilePathField(path=images_path)
Changed in version 3.0: path
can now be a callable.
- FilePathField.match
- Optional. A regular expression, as a string, that FilePathField will use to filter filenames. Note that the regex will be applied to the base filename, not the full path. Example:
"foo.*\.txt$"
, which will match a file called foo23.txt
but not bar.txt
or foo23.png
.
- FilePathField.recursive
- Optional. Either
True
or False
. Default is False
. Specifies whether all subdirectories of path should be included
- FilePathField.allow_files
- Optional. Either
True
or False
. Default is True
. Specifies whether files in the specified location should be included. Either this or allow_folders must be True
.
- FilePathField.allow_folders
- Optional. Either
True
or False
. Default is False
. Specifies whether folders in the specified location should be included. Either this or allow_files must be True
.
The one potential gotcha is that match applies to the base filename, not the full path. So, this example:
FilePathField(path="/home/images", match="foo.*", recursive=True)
…will match /home/images/foo.png
but not /home/images/foo/bar.png
because the match applies to the base filename (foo.png
and bar.png
).
FilePathField instances are created in your database as varchar
columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the max_length argument.
FloatField
- class FloatField(**options)
A floating-point number represented in Python by a float
instance.
The default form widget for this field is a NumberInput when localize is False
or TextInput otherwise.
FloatField
vs. DecimalField
The FloatField class is sometimes mixed up with the DecimalField class. Although they both represent real numbers, they represent those numbers differently. FloatField
uses Python’s float
type internally, while DecimalField
uses Python’s Decimal
type. For information on the difference between the two, see Python’s documentation for the decimal
module.
ImageField
- class ImageField(upload_to=None, height_field=None, width_field=None, max_length=100, **options)
Inherits all attributes and methods from FileField, but also validates that the uploaded object is a valid image.
In addition to the special attributes that are available for FileField, an ImageField also has height
and width
attributes.
To facilitate querying on those attributes, ImageField has two extra optional arguments:
- ImageField.height_field
- Name of a model field which will be auto-populated with the height of the image each time the model instance is saved.
- ImageField.width_field
- Name of a model field which will be auto-populated with the width of the image each time the model instance is saved.
Requires the Pillow library.
ImageField instances are created in your database as varchar
columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the max_length argument.
The default form widget for this field is a ClearableFileInput.
IntegerField
- class IntegerField(**options)
An integer. Values from -2147483648
to 2147483647
are safe in all databases supported by Django.
It uses MinValueValidator and MaxValueValidator to validate the input based on the values that the default database supports.
The default form widget for this field is a NumberInput when localize is False
or TextInput otherwise.
GenericIPAddressField
- class GenericIPAddressField(protocol='both', unpack_ipv4=False, **options)
An IPv4 or IPv6 address, in string format (e.g. 192.0.2.30
or 2a02:42fe::4
). The default form widget for this field is a TextInput.
The IPv6 address normalization follows RFC 4291#section-2.2 section 2.2, including using the IPv4 format suggested in paragraph 3 of that section, like ::ffff:192.0.2.0
. For example, 2001:0::0:01
would be normalized to 2001::1
, and ::ffff:0a0a:0a0a
to ::ffff:10.10.10.10
. All characters are converted to lowercase.
- GenericIPAddressField.protocol
- Limits valid inputs to the specified protocol. Accepted values are
'both'
(default), 'IPv4'
or 'IPv6'
. Matching is case insensitive.
- GenericIPAddressField.unpack_ipv4
- Unpacks IPv4 mapped addresses like
::ffff:192.0.2.1
. If this option is enabled that address would be unpacked to 192.0.2.1
. Default is disabled. Can only be used when protocol
is set to 'both'
.
If you allow for blank values, you have to allow for null values since blank values are stored as null.
JSONField
- class JSONField(encoder=None, decoder=None, **options)
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
.
JSONField
is supported on MariaDB 10.2.7+, MySQL 5.7.8+, Oracle, PostgreSQL, and SQLite 3.9.0+ (with the JSON1 extension enabled).
- JSONField.encoder
An optional json.JSONEncoder
subclass to serialize data types not supported by the standard JSON serializer (e.g. datetime.datetime
or UUID
). For example, you can use the DjangoJSONEncoder class.
Defaults to json.JSONEncoder
.
- JSONField.decoder
An optional json.JSONDecoder
subclass to deserialize the value retrieved from the database. The value will be in the format chosen by the custom encoder (most often a string). 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 a datetime
that was actually a string that just happened to be in the same format chosen for datetime
s.
Defaults to json.JSONDecoder
.
If you give the field a default, ensure it’s an immutable object, such as a str
, or a callable object that returns a fresh mutable object each time, such as dict
or a function. Providing a mutable default object like default={}
or default=[]
shares the one object between all model instances.
To query JSONField
in the database, see Querying JSONField.
Indexing
Index and Field.db_index both create a B-tree index, which isn’t particularly helpful when querying JSONField
. On PostgreSQL only, you can use GinIndex that is better suited.
PostgreSQL users
PostgreSQL has two native JSON based data types: json
and jsonb
. The main difference between them is how they are stored and how they can be queried. PostgreSQL’s json
field is stored as the original string representation of the JSON and must be decoded on the fly when queried based on keys. The jsonb
field is stored based on the actual structure of the JSON which allows indexing. The trade-off is a small additional cost on writing to the jsonb
field. JSONField
uses jsonb
.
Oracle users
Oracle Database does not support storing JSON scalar values. Only JSON objects and arrays (represented in Python using dict
and list
) are supported.
NullBooleanField
- class NullBooleanField(**options)
Like BooleanField with null=True
.
Deprecated since version 3.1: NullBooleanField
is deprecated in favor of BooleanField(null=True)
.
PositiveBigIntegerField
- class PositiveBigIntegerField(**options)
Like a PositiveIntegerField, but only allows values under a certain (database-dependent) point. Values from 0
to 9223372036854775807
are safe in all databases supported by Django.
PositiveIntegerField
- class PositiveIntegerField(**options)
Like an IntegerField, but must be either positive or zero (0
). Values from 0
to 2147483647
are safe in all databases supported by Django. The value 0
is accepted for backward compatibility reasons.
PositiveSmallIntegerField
- class PositiveSmallIntegerField(**options)
Like a PositiveIntegerField, but only allows values under a certain (database-dependent) point. Values from 0
to 32767
are safe in all databases supported by Django.
SlugField
- class SlugField(max_length=50, **options)
Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. They’re generally used in URLs.
Like a CharField, you can specify max_length (read the note about database portability and max_length in that section, too). If max_length is not specified, Django will use a default length of 50.
Implies setting Field.db_index to True
.
It is often useful to automatically prepopulate a SlugField based on the value of some other value. You can do this automatically in the admin using prepopulated_fields.
It uses validate_slug or validate_unicode_slug for validation.
- SlugField.allow_unicode
- If
True
, the field accepts Unicode letters in addition to ASCII letters. Defaults to False
.
SmallAutoField
- class SmallAutoField(**options)
Like an AutoField, but only allows values under a certain (database-dependent) limit. Values from 1
to 32767
are safe in all databases supported by Django.
SmallIntegerField
- class SmallIntegerField(**options)
Like an IntegerField, but only allows values under a certain (database-dependent) point. Values from -32768
to 32767
are safe in all databases supported by Django.
TextField
- class TextField(**options)
A large text field. The default form widget for this field is a Textarea.
If you specify a max_length
attribute, it will be reflected in the Textarea widget of the auto-generated form field. However it is not enforced at the model or database level. Use a CharField for that.
TimeField
- class TimeField(auto_now=False, auto_now_add=False, **options)
A time, represented in Python by a datetime.time
instance. Accepts the same auto-population options as DateField.
The default form widget for this field is a TimeInput. The admin adds some JavaScript shortcuts.
UUIDField
- class UUIDField(**options)
A field for storing universally unique identifiers. Uses Python’s UUID
class. When used on PostgreSQL, this stores in a uuid
datatype, otherwise in a char(32)
.
Universally unique identifiers are a good alternative to AutoField for primary_key. The database will not generate the UUID for you, so it is recommended to use default:
import uuid
from django.db import models
class MyUUIDModel(models.Model):
id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
# other fields
Note that a callable (with the parentheses omitted) is passed to default
, not an instance of UUID
.
Lookups on PostgreSQL
Using :lookup:`iexact`, :lookup:`contains`, :lookup:`icontains`, :lookup:`startswith`, :lookup:`istartswith`, :lookup:`endswith`, or :lookup:`iendswith` lookups on PostgreSQL don’t work for values without hyphens, because PostgreSQL stores them in a hyphenated uuid datatype type.