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Added a db_type() method to the database Field class. This is a hook for calculating the database column type for a given Field. Also converted all management.py CREATE TABLE statements to use db_type(), which made that code cleaner. The Field.get_internal_type() hook still exists, but we should consider removing it at some point, because db_type() is more general. Also added docs -- the beginnings of docs on how to create custom database Field classes. This is backwards-compatible. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5725 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Adrian Holovaty 2007-07-20 06:28:56 +00:00
parent f5ef3bec68
commit ac2b9f2a3f
10 changed files with 137 additions and 44 deletions
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52
django/core/management.py
View File

@ -95,19 +95,12 @@ def _get_sequence_list():
return sequence_list
# If the foreign key points to an AutoField, a PositiveIntegerField or a
# PositiveSmallIntegerField, the foreign key should be an IntegerField, not the
# referred field type. Otherwise, the foreign key should be the same type of
# field as the field to which it points.
get_rel_data_type = lambda f: (f.get_internal_type() in ('AutoField', 'PositiveIntegerField', 'PositiveSmallIntegerField')) and 'IntegerField' or f.get_internal_type()
def get_sql_create(app):
"Returns a list of the CREATE TABLE SQL statements for the given app."
from django.db import get_creation_module, models
from django.db import models
from django.conf import settings
data_types = get_creation_module().DATA_TYPES
if not data_types:
if settings.DATABASE_ENGINE == 'dummy':
# This must be the "dummy" database backend, which means the user
# hasn't set DATABASE_ENGINE.
sys.stderr.write(style.ERROR("Error: Django doesn't know which syntax to use for your SQL statements,\n" +
@ -159,28 +152,19 @@ def _get_sql_model_create(model, known_models=set()):
Returns list_of_sql, pending_references_dict
"""
from django.db import backend, get_creation_module, models
data_types = get_creation_module().DATA_TYPES
from django.db import backend, models
opts = model._meta
final_output = []
table_output = []
pending_references = {}
for f in opts.fields:
if isinstance(f, (models.ForeignKey, models.OneToOneField)):
rel_field = f.rel.get_related_field()
while isinstance(rel_field, (models.ForeignKey, models.OneToOneField)):
rel_field = rel_field.rel.get_related_field()
data_type = get_rel_data_type(rel_field)
else:
rel_field = f
data_type = f.get_internal_type()
col_type = data_types[data_type]
col_type = f.db_type()
tablespace = f.db_tablespace or opts.db_tablespace
if col_type is not None:
# Make the definition (e.g. 'foo VARCHAR(30)') for this field.
field_output = [style.SQL_FIELD(backend.quote_name(f.column)),
style.SQL_COLTYPE(col_type % rel_field.__dict__)]
style.SQL_COLTYPE(col_type)]
field_output.append(style.SQL_KEYWORD('%sNULL' % (not f.null and 'NOT ' or '')))
if f.unique and (not f.primary_key or backend.allows_unique_and_pk):
field_output.append(style.SQL_KEYWORD('UNIQUE'))
@ -204,7 +188,7 @@ def _get_sql_model_create(model, known_models=set()):
table_output.append(' '.join(field_output))
if opts.order_with_respect_to:
table_output.append(style.SQL_FIELD(backend.quote_name('_order')) + ' ' + \
style.SQL_COLTYPE(data_types['IntegerField']) + ' ' + \
style.SQL_COLTYPE(models.IntegerField().db_type()) + ' ' + \
style.SQL_KEYWORD('NULL'))
for field_constraints in opts.unique_together:
table_output.append(style.SQL_KEYWORD('UNIQUE') + ' (%s)' % \
@ -232,9 +216,8 @@ def _get_sql_for_pending_references(model, pending_references):
"""
Get any ALTER TABLE statements to add constraints after the fact.
"""
from django.db import backend, get_creation_module
from django.db import backend
from django.db.backends.util import truncate_name
data_types = get_creation_module().DATA_TYPES
final_output = []
if backend.supports_constraints:
@ -257,11 +240,9 @@ def _get_sql_for_pending_references(model, pending_references):
return final_output
def _get_many_to_many_sql_for_model(model):
from django.db import backend, get_creation_module
from django.db import backend, models
from django.contrib.contenttypes import generic
data_types = get_creation_module().DATA_TYPES
opts = model._meta
final_output = []
for f in opts.many_to_many:
@ -275,19 +256,19 @@ def _get_many_to_many_sql_for_model(model):
style.SQL_TABLE(backend.quote_name(f.m2m_db_table())) + ' (']
table_output.append(' %s %s %s%s,' % \
(style.SQL_FIELD(backend.quote_name('id')),
style.SQL_COLTYPE(data_types['AutoField']),
style.SQL_COLTYPE(models.AutoField(primary_key=True).db_type()),
style.SQL_KEYWORD('NOT NULL PRIMARY KEY'),
tablespace_sql))
table_output.append(' %s %s %s %s (%s)%s,' % \
(style.SQL_FIELD(backend.quote_name(f.m2m_column_name())),
style.SQL_COLTYPE(data_types[get_rel_data_type(opts.pk)] % opts.pk.__dict__),
style.SQL_COLTYPE(models.ForeignKey(model).db_type()),
style.SQL_KEYWORD('NOT NULL REFERENCES'),
style.SQL_TABLE(backend.quote_name(opts.db_table)),
style.SQL_FIELD(backend.quote_name(opts.pk.column)),
backend.get_deferrable_sql()))
table_output.append(' %s %s %s %s (%s)%s,' % \
(style.SQL_FIELD(backend.quote_name(f.m2m_reverse_name())),
style.SQL_COLTYPE(data_types[get_rel_data_type(f.rel.to._meta.pk)] % f.rel.to._meta.pk.__dict__),
style.SQL_COLTYPE(models.ForeignKey(f.rel.to).db_type()),
style.SQL_KEYWORD('NOT NULL REFERENCES'),
style.SQL_TABLE(backend.quote_name(f.rel.to._meta.db_table)),
style.SQL_FIELD(backend.quote_name(f.rel.to._meta.pk.column)),
@ -517,7 +498,7 @@ def _emit_post_sync_signal(created_models, verbosity, interactive):
def syncdb(verbosity=1, interactive=True):
"Creates the database tables for all apps in INSTALLED_APPS whose tables haven't already been created."
from django.db import backend, connection, transaction, models, get_creation_module
from django.db import backend, connection, transaction, models
from django.conf import settings
disable_termcolors()
@ -533,8 +514,6 @@ def syncdb(verbosity=1, interactive=True):
except ImportError:
pass
data_types = get_creation_module().DATA_TYPES
cursor = connection.cursor()
# Get a list of all existing database tables,
@ -1266,8 +1245,7 @@ runserver.args = '[--noreload] [--adminmedia=ADMIN_MEDIA_PATH] [optional port nu
def createcachetable(tablename):
"Creates the table needed to use the SQL cache backend"
from django.db import backend, connection, transaction, get_creation_module, models
data_types = get_creation_module().DATA_TYPES
from django.db import backend, connection, transaction, models
fields = (
# "key" is a reserved word in MySQL, so use "cache_key" instead.
models.CharField(name='cache_key', maxlength=255, unique=True, primary_key=True),
@ -1277,7 +1255,7 @@ def createcachetable(tablename):
table_output = []
index_output = []
for f in fields:
field_output = [backend.quote_name(f.name), data_types[f.get_internal_type()] % f.__dict__]
field_output = [backend.quote_name(f.name), f.db_type()]
field_output.append("%sNULL" % (not f.null and "NOT " or ""))
if f.unique:
field_output.append("UNIQUE")

1
django/db/backends/ado_mssql/creation.py
View File

@ -12,7 +12,6 @@ DATA_TYPES = {
'ImageField': 'varchar(100)',
'IntegerField': 'int',
'IPAddressField': 'char(15)',
'ManyToManyField': None,
'NullBooleanField': 'bit',
'OneToOneField': 'int',
'PhoneNumberField': 'varchar(20)',

1
django/db/backends/mysql/creation.py
View File

@ -16,7 +16,6 @@ DATA_TYPES = {
'ImageField': 'varchar(100)',
'IntegerField': 'integer',
'IPAddressField': 'char(15)',
'ManyToManyField': None,
'NullBooleanField': 'bool',
'OneToOneField': 'integer',
'PhoneNumberField': 'varchar(20)',

1
django/db/backends/mysql_old/creation.py
View File

@ -16,7 +16,6 @@ DATA_TYPES = {
'ImageField': 'varchar(100)',
'IntegerField': 'integer',
'IPAddressField': 'char(15)',
'ManyToManyField': None,
'NullBooleanField': 'bool',
'OneToOneField': 'integer',
'PhoneNumberField': 'varchar(20)',

1
django/db/backends/oracle/creation.py
View File

@ -19,7 +19,6 @@ DATA_TYPES = {
'ImageField': 'NVARCHAR2(100)',
'IntegerField': 'NUMBER(11)',
'IPAddressField': 'VARCHAR2(15)',
'ManyToManyField': None,
'NullBooleanField': 'NUMBER(1) CHECK ((%(column)s IN (0,1)) OR (%(column)s IS NULL))',
'OneToOneField': 'NUMBER(11)',
'PhoneNumberField': 'VARCHAR2(20)',

1
django/db/backends/postgresql/creation.py
View File

@ -16,7 +16,6 @@ DATA_TYPES = {
'ImageField': 'varchar(100)',
'IntegerField': 'integer',
'IPAddressField': 'inet',
'ManyToManyField': None,
'NullBooleanField': 'boolean',
'OneToOneField': 'integer',
'PhoneNumberField': 'varchar(20)',

1
django/db/backends/sqlite3/creation.py
View File

@ -15,7 +15,6 @@ DATA_TYPES = {
'ImageField': 'varchar(100)',
'IntegerField': 'integer',
'IPAddressField': 'char(15)',
'ManyToManyField': None,
'NullBooleanField': 'bool',
'OneToOneField': 'integer',
'PhoneNumberField': 'varchar(20)',

25
django/db/models/fields/__init__.py
View File

@ -1,3 +1,4 @@
from django.db import get_creation_module
from django.db.models import signals
from django.dispatch import dispatcher
from django.conf import settings
@ -117,6 +118,30 @@ class Field(object):
"""
return value
def db_type(self):
"""
Returns the database column data type for this field, taking into
account the DATABASE_ENGINE setting.
"""
# The default implementation of this method looks at the
# backend-specific DATA_TYPES dictionary, looking up the field by its
# "internal type".
#
# A Field class can implement the get_internal_type() method to specify
# which *preexisting* Django Field class it's most similar to -- i.e.,
# an XMLField is represented by a TEXT column type, which is the same
# as the TextField Django field type, which means XMLField's
# get_internal_type() returns 'TextField'.
#
# But the limitation of the get_internal_type() / DATA_TYPES approach
# is that it cannot handle database column types that aren't already
# mapped to one of the built-in Django field types. In this case, you
# can implement db_type() instead of get_internal_type() to specify
# exactly which wacky database column type you want to use.
data_types = get_creation_module().DATA_TYPES
internal_type = self.get_internal_type()
return data_types[internal_type] % self.__dict__
def validate_full(self, field_data, all_data):
"""
Returns a list of errors for this field. This is the main interface,

27
django/db/models/fields/related.py
View File

@ -1,6 +1,6 @@
from django.db import backend, transaction
from django.db.models import signals, get_model
from django.db.models.fields import AutoField, Field, IntegerField, get_ul_class
from django.db.models.fields import AutoField, Field, IntegerField, PositiveIntegerField, PositiveSmallIntegerField, get_ul_class
from django.db.models.related import RelatedObject
from django.utils.text import capfirst
from django.utils.translation import ugettext_lazy, string_concat, ungettext, ugettext as _
@ -556,6 +556,16 @@ class ForeignKey(RelatedField, Field):
defaults.update(kwargs)
return super(ForeignKey, self).formfield(**defaults)
def db_type(self):
# The database column type of a ForeignKey is the column type
# of the field to which it points. An exception is if the ForeignKey
# points to an AutoField/PositiveIntegerField/PositiveSmallIntegerField,
# in which case the column type is simply that of an IntegerField.
rel_field = self.rel.get_related_field()
if isinstance(rel_field, (AutoField, PositiveIntegerField, PositiveSmallIntegerField)):
return IntegerField().db_type()
return rel_field.db_type()
class OneToOneField(RelatedField, IntegerField):
def __init__(self, to, to_field=None, **kwargs):
try:
@ -622,6 +632,16 @@ class OneToOneField(RelatedField, IntegerField):
defaults.update(kwargs)
return super(OneToOneField, self).formfield(**defaults)
def db_type(self):
# The database column type of a OneToOneField is the column type
# of the field to which it points. An exception is if the OneToOneField
# points to an AutoField/PositiveIntegerField/PositiveSmallIntegerField,
# in which case the column type is simply that of an IntegerField.
rel_field = self.rel.get_related_field()
if isinstance(rel_field, (AutoField, PositiveIntegerField, PositiveSmallIntegerField)):
return IntegerField().db_type()
return rel_field.db_type()
class ManyToManyField(RelatedField, Field):
def __init__(self, to, **kwargs):
kwargs['verbose_name'] = kwargs.get('verbose_name', None)
@ -745,6 +765,11 @@ class ManyToManyField(RelatedField, Field):
defaults['initial'] = [i._get_pk_val() for i in defaults['initial']]
return super(ManyToManyField, self).formfield(**defaults)
def db_type(self):
# A ManyToManyField is not represented by a single column,
# so return None.
return None
class ManyToOneRel(object):
def __init__(self, to, field_name, num_in_admin=3, min_num_in_admin=None,
max_num_in_admin=None, num_extra_on_change=1, edit_inline=False,

71
docs/model-api.txt
View File

@ -981,6 +981,77 @@ See the `One-to-one relationship model example`_ for a full example.
.. _One-to-one relationship model example: http://www.djangoproject.com/documentation/models/one_to_one/
Custom field types
------------------
**New in Django development version**
Django's built-in field types don't cover every possible database column type --
only the common types, such as ``VARCHAR`` and ``INTEGER``. For more obscure
column types, such as geographic polygons or even user-created types such as
`PostgreSQL custom types`_, you can define your own Django ``Field`` subclasses.
.. _PostgreSQL custom types: http://www.postgresql.org/docs/8.2/interactive/sql-createtype.html
.. admonition:: Experimental territory
This is an area of Django that traditionally has not been documented, but
we're starting to include bits of documentation, one feature at a time.
Please forgive the sparseness of this section.
If you like living on the edge and are comfortable with the risk of
unstable, undocumented APIs, see the code for the core ``Field`` class
in ``django/db/models/fields/__init__.py`` -- but if/when the innards
change, don't say we didn't warn you.
To create a custom field type, simply subclass ``django.db.models.Field``.
Here is an incomplete list of the methods you should implement:
``db_type()``
~~~~~~~~~~~~~
Returns the database column data type for the ``Field``, taking into account
the current ``DATABASE_ENGINE`` setting.
Say you've created a PostgreSQL custom type called ``mytype``. You can use this
field with Django by subclassing ``Field`` and implementing the ``db_type()``
method, like so::
from django.db import models
class MytypeField(models.Field):
def db_type(self):
return 'mytype'
Once you have ``MytypeField``, you can use it in any model, just like any other
``Field`` type::
class Person(models.Model):
name = models.CharField(maxlength=80)
gender = models.CharField(maxlength=1)
something_else = MytypeField()
If you aim to build a database-agnostic application, you should account for
differences in database column types. For example, the date/time column type
in PostgreSQL is called ``timestamp``, while the same column in MySQL is called
``datetime``. The simplest way to handle this in a ``db_type()`` method is to
import the Django settings module and check the ``DATABASE_ENGINE`` setting.
For example::
class MyDateField(models.Field):
def db_type(self):
from django.conf import settings
if settings.DATABASE_ENGINE == 'mysql':
return 'datetime'
else:
return 'timestamp'
The ``db_type()`` method is only called by Django when the framework constructs
the ``CREATE TABLE`` statements for your application -- that is, when you first
create your tables. It's not called at any other time, so it can afford to
execute slightly complex code, such as the ``DATABASE_ENGINE`` check in the
above example.
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