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from django.conf import settings
from django.core.cache import caches
from django.core.cache.backends.db import BaseDatabaseCache
from django.core.management.base import BaseCommand, CommandError
from django.db import (
DEFAULT_DB_ALIAS,
DatabaseError,
connections,
models,
router,
transaction,
)
class Command(BaseCommand):
help = "Creates the tables needed to use the SQL cache backend."
requires_system_checks = []
def add_arguments(self, parser):
parser.add_argument(
"args",
metavar="table_name",
nargs="*",
help=(
"Optional table names. Otherwise, settings.CACHES is used to find "
"cache tables."
),
)
parser.add_argument(
"--database",
default=DEFAULT_DB_ALIAS,
help="Nominates a database onto which the cache tables will be "
'installed. Defaults to the "default" database.',
)
parser.add_argument(
"--dry-run",
action="store_true",
help="Does not create the table, just prints the SQL that would be run.",
)
def handle(self, *tablenames, **options):
db = options["database"]
self.verbosity = options["verbosity"]
dry_run = options["dry_run"]
if tablenames:
# Legacy behavior, tablename specified as argument
for tablename in tablenames:
self.create_table(db, tablename, dry_run)
else:
for cache_alias in settings.CACHES:
cache = caches[cache_alias]
if isinstance(cache, BaseDatabaseCache):
self.create_table(db, cache._table, dry_run)
def create_table(self, database, tablename, dry_run):
cache = BaseDatabaseCache(tablename, {})
if not router.allow_migrate_model(database, cache.cache_model_class):
return
connection = connections[database]
if tablename in connection.introspection.table_names():
if self.verbosity > 0:
self.stdout.write("Cache table '%s' already exists." % tablename)
return
fields = (
# "key" is a reserved word in MySQL, so use "cache_key" instead.
models.CharField(
name="cache_key", max_length=255, unique=True, primary_key=True
),
models.TextField(name="value"),
models.DateTimeField(name="expires", db_index=True),
)
table_output = []
index_output = []
qn = connection.ops.quote_name
for f in fields:
field_output = [
qn(f.name),
f.db_type(connection=connection),
"%sNULL" % ("NOT " if not f.null else ""),
]
if f.primary_key:
field_output.append("PRIMARY KEY")
elif f.unique:
field_output.append("UNIQUE")
if f.db_index:
unique = "UNIQUE " if f.unique else ""
index_output.append(
"CREATE %sINDEX %s ON %s (%s);"
% (
unique,
qn("%s_%s" % (tablename, f.name)),
qn(tablename),
qn(f.name),
)
)
table_output.append(" ".join(field_output))
full_statement = ["CREATE TABLE %s (" % qn(tablename)]
for i, line in enumerate(table_output):
full_statement.append(
" %s%s" % (line, "," if i < len(table_output) - 1 else "")
)
full_statement.append(");")
full_statement = "\n".join(full_statement)
if dry_run:
self.stdout.write(full_statement)
for statement in index_output:
self.stdout.write(statement)
return
with transaction.atomic(
using=database, savepoint=connection.features.can_rollback_ddl
):
with connection.cursor() as curs:
try:
curs.execute(full_statement)
except DatabaseError as e:
raise CommandError(
"Cache table '%s' could not be created.\nThe error was: %s."
% (tablename, e)
)
for statement in index_output:
curs.execute(statement)
if self.verbosity > 1:
self.stdout.write("Cache table '%s' created." % tablename)
|
