This document contains all the gory details about all the field options and field types Django’s got to offer.
See also
If the built-in fields don’t do the trick, you can try
django.contrib.localflavor
, which contains assorted pieces of code
that are useful for particular countries or cultures. Also, you can easily
write your own custom model fields.
Note
Technically, these models are defined in django.db.models.fields
, but
for convenience they’re imported into django.db.models
; the standard
convention is to use from django.db import models
and refer to fields as
models.<Foo>Field
.
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
.
Note that empty string values will always get stored as empty strings, not as
NULL
. Only use null=True
for non-string fields such as integers,
booleans and dates. For both types of 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
).
Avoid using null
on string-based fields such as
CharField
and TextField
unless you have an excellent reason.
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;” Django convention is to use the empty
string, not NULL
.
Note
When using the Oracle database backend, the null=True
option will be
coerced for string-based fields that have the empty string as a possible
value, and the value NULL
will be stored to denote the empty string.
If you want to accept null
values with BooleanField
,
use NullBooleanField
instead.
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
¶An iterable (e.g., a list or tuple) of 2-tuples to use as choices for this field. If this is given, 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 stored, 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'),
)
The first element in each tuple is the actual value to be stored. The second element is the human-readable name for the option.
The choices list can be defined either as part of your model class:
class Foo(models.Model):
YEAR_IN_SCHOOL_CHOICES = (
('FR', 'Freshman'),
('SO', 'Sophomore'),
('JR', 'Junior'),
('SR', 'Senior'),
('GR', 'Graduate'),
)
year_in_school = models.CharField(max_length=2, choices=YEAR_IN_SCHOOL_CHOICES)
or outside your model class altogether:
YEAR_IN_SCHOOL_CHOICES = (
('FR', 'Freshman'),
('SO', 'Sophomore'),
('JR', 'Junior'),
('SR', 'Senior'),
('GR', 'Graduate'),
)
class Foo(models.Model):
year_in_school = models.CharField(max_length=2, choices=YEAR_IN_SCHOOL_CHOICES)
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.
Finally, note that choices can be any iterable 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.
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
, djadmin:django-admin.py sqlindexes <sqlindexes> will output a
CREATE INDEX
statement for this field.
db_tablespace
¶Field.
db_tablespace
¶The name of the database tablespace to use for
this field’s index, if this field is indexed. The default is the project’s
DEFAULT_INDEX_TABLESPACE
setting, if set, or the
db_tablespace
of the model, if any. If the backend doesn’t
support tablespaces for indexes, this option is ignored.
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 cannot 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 had a custom JSONField
and wanted to specify
a dictionary as the default, use a lambda
as follows:
contact_info = JSONField("ContactInfo", default=lambda:{"email": "to1@example.com"})
editable
¶Field.
editable
¶If False
, the field will not be displayed in the admin or any other
ModelForm
. 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
,
and unique
. Additional error message keys are specified for each field in
the Field types section below.
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.
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.
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
FileField
.
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
.
This is enforced by model validation but not at the database level.
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.
AutoField
¶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.
BigIntegerField
¶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 TextInput
.
BooleanField
¶BooleanField
(**options)¶A true/false field.
The default form widget for this field is a
CheckboxInput
.
If you need to accept null
values then use
NullBooleanField
instead.
BooleanFields
would return their data as ints
, instead of true bools
. See the
release notes for a complete description of the change.CharField
¶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.
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.
MySQL users
If you are using this field with MySQLdb 1.2.2 and the utf8_bin
collation (which is not the default), there are some issues to be aware
of. Refer to the MySQL database notes for
details.
CommaSeparatedIntegerField
¶CommaSeparatedIntegerField
(max_length=None[, **options])¶A field of integers separated by commas. As in CharField
, the
max_length
argument is required and the note about database
portability mentioned there should be heeded.
DateField
¶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.
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.
The default form widget for this field is a
TextInput
. The admin adds a JavaScript calendar,
and a shortcut for “Today”. Includes an additional invalid_date
error
message key.
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.
DateTimeField
¶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
TextInput
. The admin uses two separate
TextInput
widgets with JavaScript shortcuts.
DecimalField
¶DecimalField
(max_digits=None, decimal_places=None[, **options])¶A fixed-precision decimal number, represented in Python by a
Decimal
instance. 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
, if it exists.
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 TextInput
.
Note
For more information about the differences between the
FloatField
and DecimalField
classes, please
see FloatField vs. DecimalField.
EmailField
¶EmailField
([max_length=75, **options])¶A CharField
that checks that the value is a valid email address.
FileField
¶FileField
(upload_to=None[, max_length=100, **options])¶A file-upload field.
Note
The primary_key
and unique
arguments are not supported, and will
raise a TypeError
if used.
Has one required argument:
FileField.
upload_to
¶A local filesystem path that will be appended to your MEDIA_ROOT
setting to determine the value of the url
attribute.
This path 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).
This may also be a callable, such as a function, which will be called to obtain the upload path, including the filename. This callable must be able to accept two arguments, and return a Unix-style path (with forward slashes) to be passed along to the storage system. The two arguments that will be passed are:
Argument | Description |
---|---|
instance |
An instance of the model where the
In most cases, this object will not have been
saved to the database yet, so if it uses the
default |
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. |
Also has one optional argument:
FileField.
storage
¶Optional. A storage object, which handles the storage and retrieval of your files. See Managing files for details on how to provide this object.
The default form widget for this field is a
FileInput
.
Using a FileField
or an ImageField
(see below) in a model
takes a few steps:
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
MEDIA_URL
as the base public URL of that directory. Make sure
that this directory is writable by the Web server’s user account.FileField
or ImageField
to your model, making
sure to define the upload_to
option to tell Django
to which subdirectory of MEDIA_ROOT
it should upload files.MEDIA_ROOT
). You’ll most likely want to use the
convenience url
function 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
{{ object.mug_shot.url }}
.For example, say your 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.
By default, FileField
instances are
created as varchar(100)
columns in your database. As with other fields, you
can change the maximum length using the max_length
argument.
When you access a FileField
on a model, you are given an instance
of FieldFile
as a proxy for accessing the underlying file. This
class has several methods that can be used to interact with file data:
FieldFile.
open
(mode='rb')¶Behaves like the standard Python open()
method and opens the file
associated with this instance in the mode specified by 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 instance is
saved after the file 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('/tmp/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 instance is saved
after the file 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
¶FilePathField
(path=None[, match=None, recursive=False, max_length=100, **options])¶A CharField
whose choices are limited to the filenames in a certain
directory on the filesystem. Has three 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"
.
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.gif
.
FilePathField.
recursive
¶Optional. Either True
or False
. Default is False
. Specifies
whether all subdirectories of path
should be included
Of course, these arguments can be used together.
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.gif
but not /home/images/foo/bar.gif
because the match
applies to the base filename
(foo.gif
and bar.gif
).
By default, FilePathField
instances are
created as varchar(100)
columns in your database. As with other fields, you
can change the maximum length using the max_length
argument.
FloatField
¶FloatField
([**options])¶A floating-point number represented in Python by a float
instance.
The default form widget for this field is a TextInput
.
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
¶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 Python Imaging Library.
By default, ImageField
instances are created as varchar(100)
columns in your database. As with other fields, you can change the maximum
length using the max_length
argument.
IntegerField
¶IntegerField
([**options])¶An integer. The default form widget for this field is a
TextInput
.
IPAddressField
¶IPAddressField
([**options])¶An IP address, in string format (e.g. “192.0.2.30”). The default form widget
for this field is a TextInput
.
GenericIPAddressField
¶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'
.
NullBooleanField
¶NullBooleanField
([**options])¶Like a BooleanField
, but allows NULL
as one of the options. Use
this instead of a BooleanField
with null=True
. The default form
widget for this field is a NullBooleanSelect
.
PositiveIntegerField
¶PositiveIntegerField
([**options])¶Like an IntegerField
, but must be either positive or zero (0).
The value 0 is accepted for backward compatibility reasons.
PositiveSmallIntegerField
¶PositiveSmallIntegerField
([**options])¶Like a PositiveIntegerField
, but only allows values under a certain
(database-dependent) point.
SlugField
¶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
.
SmallIntegerField
¶SmallIntegerField
([**options])¶Like an IntegerField
, but only allows values under a certain
(database-dependent) point.
TextField
¶TextField
([**options])¶A large text field. The default form widget for this field is a
Textarea
.
MySQL users
If you are using this field with MySQLdb 1.2.1p2 and the utf8_bin
collation (which is not the default), there are some issues to be aware
of. Refer to the MySQL database notes for
details.
TimeField
¶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 TextInput
.
The admin adds some JavaScript shortcuts.
URLField
¶URLField
([verify_exists=False, max_length=200, **options])¶A CharField
for a URL. Has one extra optional argument:
Deprecated since version 1.4: verify_exists
is deprecated for security reasons as of 1.4 and will be
removed in Django 1.5. Prior to 1.3.1, the default value was True
.
URLField.
verify_exists
¶If True
, the URL given will be checked for existence (i.e.,
the URL actually loads and doesn’t give a 404 response) using a
HEAD
request. Redirects are allowed, but will not be followed.
Note that when you’re using the single-threaded development server, validating a URL being served by the same server will hang. This should not be a problem for multithreaded servers.
The default form widget for this field is a TextInput
.
Like all CharField
subclasses, URLField
takes the optional
max_length
, a default of 200 is used.
Nov 29, 2016