mirror of https://github.com/django/django.git
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
parent
f5ef3bec68
commit
ac2b9f2a3f
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@ -95,19 +95,12 @@ def _get_sequence_list():
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return sequence_list
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# If the foreign key points to an AutoField, a PositiveIntegerField or a
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# PositiveSmallIntegerField, the foreign key should be an IntegerField, not the
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# referred field type. Otherwise, the foreign key should be the same type of
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# field as the field to which it points.
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get_rel_data_type = lambda f: (f.get_internal_type() in ('AutoField', 'PositiveIntegerField', 'PositiveSmallIntegerField')) and 'IntegerField' or f.get_internal_type()
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def get_sql_create(app):
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"Returns a list of the CREATE TABLE SQL statements for the given app."
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from django.db import get_creation_module, models
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from django.db import models
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from django.conf import settings
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data_types = get_creation_module().DATA_TYPES
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if not data_types:
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if settings.DATABASE_ENGINE == 'dummy':
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# This must be the "dummy" database backend, which means the user
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# hasn't set DATABASE_ENGINE.
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sys.stderr.write(style.ERROR("Error: Django doesn't know which syntax to use for your SQL statements,\n" +
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@ -159,28 +152,19 @@ def _get_sql_model_create(model, known_models=set()):
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Returns list_of_sql, pending_references_dict
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"""
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from django.db import backend, get_creation_module, models
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data_types = get_creation_module().DATA_TYPES
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from django.db import backend, models
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opts = model._meta
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final_output = []
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table_output = []
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pending_references = {}
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for f in opts.fields:
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if isinstance(f, (models.ForeignKey, models.OneToOneField)):
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rel_field = f.rel.get_related_field()
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while isinstance(rel_field, (models.ForeignKey, models.OneToOneField)):
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rel_field = rel_field.rel.get_related_field()
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data_type = get_rel_data_type(rel_field)
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else:
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rel_field = f
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data_type = f.get_internal_type()
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col_type = data_types[data_type]
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col_type = f.db_type()
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tablespace = f.db_tablespace or opts.db_tablespace
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if col_type is not None:
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# Make the definition (e.g. 'foo VARCHAR(30)') for this field.
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field_output = [style.SQL_FIELD(backend.quote_name(f.column)),
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style.SQL_COLTYPE(col_type % rel_field.__dict__)]
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style.SQL_COLTYPE(col_type)]
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field_output.append(style.SQL_KEYWORD('%sNULL' % (not f.null and 'NOT ' or '')))
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if f.unique and (not f.primary_key or backend.allows_unique_and_pk):
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field_output.append(style.SQL_KEYWORD('UNIQUE'))
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@ -204,7 +188,7 @@ def _get_sql_model_create(model, known_models=set()):
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table_output.append(' '.join(field_output))
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if opts.order_with_respect_to:
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table_output.append(style.SQL_FIELD(backend.quote_name('_order')) + ' ' + \
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style.SQL_COLTYPE(data_types['IntegerField']) + ' ' + \
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style.SQL_COLTYPE(models.IntegerField().db_type()) + ' ' + \
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style.SQL_KEYWORD('NULL'))
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for field_constraints in opts.unique_together:
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table_output.append(style.SQL_KEYWORD('UNIQUE') + ' (%s)' % \
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@ -232,9 +216,8 @@ def _get_sql_for_pending_references(model, pending_references):
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"""
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Get any ALTER TABLE statements to add constraints after the fact.
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"""
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from django.db import backend, get_creation_module
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from django.db import backend
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from django.db.backends.util import truncate_name
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data_types = get_creation_module().DATA_TYPES
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final_output = []
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if backend.supports_constraints:
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@ -257,11 +240,9 @@ def _get_sql_for_pending_references(model, pending_references):
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return final_output
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def _get_many_to_many_sql_for_model(model):
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from django.db import backend, get_creation_module
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from django.db import backend, models
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from django.contrib.contenttypes import generic
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data_types = get_creation_module().DATA_TYPES
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opts = model._meta
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final_output = []
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for f in opts.many_to_many:
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@ -275,19 +256,19 @@ def _get_many_to_many_sql_for_model(model):
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style.SQL_TABLE(backend.quote_name(f.m2m_db_table())) + ' (']
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table_output.append(' %s %s %s%s,' % \
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(style.SQL_FIELD(backend.quote_name('id')),
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style.SQL_COLTYPE(data_types['AutoField']),
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style.SQL_COLTYPE(models.AutoField(primary_key=True).db_type()),
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style.SQL_KEYWORD('NOT NULL PRIMARY KEY'),
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tablespace_sql))
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table_output.append(' %s %s %s %s (%s)%s,' % \
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(style.SQL_FIELD(backend.quote_name(f.m2m_column_name())),
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style.SQL_COLTYPE(data_types[get_rel_data_type(opts.pk)] % opts.pk.__dict__),
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style.SQL_COLTYPE(models.ForeignKey(model).db_type()),
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style.SQL_KEYWORD('NOT NULL REFERENCES'),
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style.SQL_TABLE(backend.quote_name(opts.db_table)),
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style.SQL_FIELD(backend.quote_name(opts.pk.column)),
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backend.get_deferrable_sql()))
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table_output.append(' %s %s %s %s (%s)%s,' % \
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(style.SQL_FIELD(backend.quote_name(f.m2m_reverse_name())),
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style.SQL_COLTYPE(data_types[get_rel_data_type(f.rel.to._meta.pk)] % f.rel.to._meta.pk.__dict__),
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style.SQL_COLTYPE(models.ForeignKey(f.rel.to).db_type()),
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style.SQL_KEYWORD('NOT NULL REFERENCES'),
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style.SQL_TABLE(backend.quote_name(f.rel.to._meta.db_table)),
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style.SQL_FIELD(backend.quote_name(f.rel.to._meta.pk.column)),
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@ -517,7 +498,7 @@ def _emit_post_sync_signal(created_models, verbosity, interactive):
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def syncdb(verbosity=1, interactive=True):
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"Creates the database tables for all apps in INSTALLED_APPS whose tables haven't already been created."
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from django.db import backend, connection, transaction, models, get_creation_module
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from django.db import backend, connection, transaction, models
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from django.conf import settings
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disable_termcolors()
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@ -533,8 +514,6 @@ def syncdb(verbosity=1, interactive=True):
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except ImportError:
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pass
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data_types = get_creation_module().DATA_TYPES
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cursor = connection.cursor()
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# Get a list of all existing database tables,
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@ -1266,8 +1245,7 @@ runserver.args = '[--noreload] [--adminmedia=ADMIN_MEDIA_PATH] [optional port nu
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def createcachetable(tablename):
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"Creates the table needed to use the SQL cache backend"
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from django.db import backend, connection, transaction, get_creation_module, models
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data_types = get_creation_module().DATA_TYPES
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from django.db import backend, connection, transaction, models
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fields = (
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# "key" is a reserved word in MySQL, so use "cache_key" instead.
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models.CharField(name='cache_key', maxlength=255, unique=True, primary_key=True),
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@ -1277,7 +1255,7 @@ def createcachetable(tablename):
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table_output = []
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index_output = []
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for f in fields:
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field_output = [backend.quote_name(f.name), data_types[f.get_internal_type()] % f.__dict__]
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field_output = [backend.quote_name(f.name), f.db_type()]
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field_output.append("%sNULL" % (not f.null and "NOT " or ""))
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if f.unique:
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field_output.append("UNIQUE")
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@ -12,7 +12,6 @@ DATA_TYPES = {
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'ImageField': 'varchar(100)',
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'IntegerField': 'int',
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'IPAddressField': 'char(15)',
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'ManyToManyField': None,
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'NullBooleanField': 'bit',
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'OneToOneField': 'int',
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'PhoneNumberField': 'varchar(20)',
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@ -16,7 +16,6 @@ DATA_TYPES = {
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'ImageField': 'varchar(100)',
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'IntegerField': 'integer',
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'IPAddressField': 'char(15)',
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'ManyToManyField': None,
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'NullBooleanField': 'bool',
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'OneToOneField': 'integer',
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'PhoneNumberField': 'varchar(20)',
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@ -16,7 +16,6 @@ DATA_TYPES = {
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'ImageField': 'varchar(100)',
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'IntegerField': 'integer',
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'IPAddressField': 'char(15)',
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'ManyToManyField': None,
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'NullBooleanField': 'bool',
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'OneToOneField': 'integer',
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'PhoneNumberField': 'varchar(20)',
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@ -19,7 +19,6 @@ DATA_TYPES = {
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'ImageField': 'NVARCHAR2(100)',
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'IntegerField': 'NUMBER(11)',
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'IPAddressField': 'VARCHAR2(15)',
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'ManyToManyField': None,
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'NullBooleanField': 'NUMBER(1) CHECK ((%(column)s IN (0,1)) OR (%(column)s IS NULL))',
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'OneToOneField': 'NUMBER(11)',
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'PhoneNumberField': 'VARCHAR2(20)',
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@ -16,7 +16,6 @@ DATA_TYPES = {
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'ImageField': 'varchar(100)',
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'IntegerField': 'integer',
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'IPAddressField': 'inet',
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'ManyToManyField': None,
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'NullBooleanField': 'boolean',
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'OneToOneField': 'integer',
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'PhoneNumberField': 'varchar(20)',
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@ -15,7 +15,6 @@ DATA_TYPES = {
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'ImageField': 'varchar(100)',
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'IntegerField': 'integer',
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'IPAddressField': 'char(15)',
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'ManyToManyField': None,
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'NullBooleanField': 'bool',
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'OneToOneField': 'integer',
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'PhoneNumberField': 'varchar(20)',
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@ -1,3 +1,4 @@
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from django.db import get_creation_module
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from django.db.models import signals
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from django.dispatch import dispatcher
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from django.conf import settings
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@ -117,6 +118,30 @@ class Field(object):
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"""
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return value
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def db_type(self):
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"""
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Returns the database column data type for this field, taking into
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account the DATABASE_ENGINE setting.
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"""
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# The default implementation of this method looks at the
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# backend-specific DATA_TYPES dictionary, looking up the field by its
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# "internal type".
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#
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# A Field class can implement the get_internal_type() method to specify
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# which *preexisting* Django Field class it's most similar to -- i.e.,
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# an XMLField is represented by a TEXT column type, which is the same
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# as the TextField Django field type, which means XMLField's
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# get_internal_type() returns 'TextField'.
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#
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# But the limitation of the get_internal_type() / DATA_TYPES approach
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# is that it cannot handle database column types that aren't already
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# mapped to one of the built-in Django field types. In this case, you
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# can implement db_type() instead of get_internal_type() to specify
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# exactly which wacky database column type you want to use.
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data_types = get_creation_module().DATA_TYPES
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internal_type = self.get_internal_type()
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return data_types[internal_type] % self.__dict__
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def validate_full(self, field_data, all_data):
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"""
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Returns a list of errors for this field. This is the main interface,
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@ -1,6 +1,6 @@
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from django.db import backend, transaction
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from django.db.models import signals, get_model
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from django.db.models.fields import AutoField, Field, IntegerField, get_ul_class
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from django.db.models.fields import AutoField, Field, IntegerField, PositiveIntegerField, PositiveSmallIntegerField, get_ul_class
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from django.db.models.related import RelatedObject
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from django.utils.text import capfirst
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from django.utils.translation import ugettext_lazy, string_concat, ungettext, ugettext as _
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@ -556,6 +556,16 @@ class ForeignKey(RelatedField, Field):
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defaults.update(kwargs)
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return super(ForeignKey, self).formfield(**defaults)
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def db_type(self):
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# The database column type of a ForeignKey is the column type
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# of the field to which it points. An exception is if the ForeignKey
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# points to an AutoField/PositiveIntegerField/PositiveSmallIntegerField,
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# in which case the column type is simply that of an IntegerField.
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rel_field = self.rel.get_related_field()
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if isinstance(rel_field, (AutoField, PositiveIntegerField, PositiveSmallIntegerField)):
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return IntegerField().db_type()
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return rel_field.db_type()
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class OneToOneField(RelatedField, IntegerField):
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def __init__(self, to, to_field=None, **kwargs):
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try:
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@ -622,6 +632,16 @@ class OneToOneField(RelatedField, IntegerField):
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defaults.update(kwargs)
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return super(OneToOneField, self).formfield(**defaults)
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def db_type(self):
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# The database column type of a OneToOneField is the column type
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# of the field to which it points. An exception is if the OneToOneField
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# points to an AutoField/PositiveIntegerField/PositiveSmallIntegerField,
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# in which case the column type is simply that of an IntegerField.
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rel_field = self.rel.get_related_field()
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if isinstance(rel_field, (AutoField, PositiveIntegerField, PositiveSmallIntegerField)):
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return IntegerField().db_type()
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return rel_field.db_type()
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class ManyToManyField(RelatedField, Field):
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def __init__(self, to, **kwargs):
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kwargs['verbose_name'] = kwargs.get('verbose_name', None)
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@ -745,6 +765,11 @@ class ManyToManyField(RelatedField, Field):
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defaults['initial'] = [i._get_pk_val() for i in defaults['initial']]
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return super(ManyToManyField, self).formfield(**defaults)
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def db_type(self):
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# A ManyToManyField is not represented by a single column,
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# so return None.
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return None
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class ManyToOneRel(object):
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def __init__(self, to, field_name, num_in_admin=3, min_num_in_admin=None,
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max_num_in_admin=None, num_extra_on_change=1, edit_inline=False,
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@ -981,6 +981,77 @@ See the `One-to-one relationship model example`_ for a full example.
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.. _One-to-one relationship model example: http://www.djangoproject.com/documentation/models/one_to_one/
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Custom field types
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------------------
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**New in Django development version**
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Django's built-in field types don't cover every possible database column type --
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only the common types, such as ``VARCHAR`` and ``INTEGER``. For more obscure
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column types, such as geographic polygons or even user-created types such as
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`PostgreSQL custom types`_, you can define your own Django ``Field`` subclasses.
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.. _PostgreSQL custom types: http://www.postgresql.org/docs/8.2/interactive/sql-createtype.html
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.. admonition:: Experimental territory
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This is an area of Django that traditionally has not been documented, but
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we're starting to include bits of documentation, one feature at a time.
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Please forgive the sparseness of this section.
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If you like living on the edge and are comfortable with the risk of
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unstable, undocumented APIs, see the code for the core ``Field`` class
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in ``django/db/models/fields/__init__.py`` -- but if/when the innards
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change, don't say we didn't warn you.
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To create a custom field type, simply subclass ``django.db.models.Field``.
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Here is an incomplete list of the methods you should implement:
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``db_type()``
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~~~~~~~~~~~~~
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Returns the database column data type for the ``Field``, taking into account
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the current ``DATABASE_ENGINE`` setting.
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Say you've created a PostgreSQL custom type called ``mytype``. You can use this
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field with Django by subclassing ``Field`` and implementing the ``db_type()``
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method, like so::
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from django.db import models
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class MytypeField(models.Field):
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def db_type(self):
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return 'mytype'
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Once you have ``MytypeField``, you can use it in any model, just like any other
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``Field`` type::
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class Person(models.Model):
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name = models.CharField(maxlength=80)
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gender = models.CharField(maxlength=1)
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something_else = MytypeField()
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If you aim to build a database-agnostic application, you should account for
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differences in database column types. For example, the date/time column type
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in PostgreSQL is called ``timestamp``, while the same column in MySQL is called
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``datetime``. The simplest way to handle this in a ``db_type()`` method is to
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import the Django settings module and check the ``DATABASE_ENGINE`` setting.
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For example::
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class MyDateField(models.Field):
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def db_type(self):
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from django.conf import settings
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if settings.DATABASE_ENGINE == 'mysql':
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return 'datetime'
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else:
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return 'timestamp'
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The ``db_type()`` method is only called by Django when the framework constructs
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the ``CREATE TABLE`` statements for your application -- that is, when you first
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create your tables. It's not called at any other time, so it can afford to
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execute slightly complex code, such as the ``DATABASE_ENGINE`` check in the
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above example.
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Meta options
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============
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