def get_db_prep_value(self, value, connection: BaseDatabaseWrapper, prepared=False) -> str:
if not value: # 避免 更新时 重新生成 单号
cursor = connection.cursor()
cursor.execute("select order_num from df_order_info ORDER by id DESC limit 0, 1")
row = cursor.fetchone() # 获取查询记录 返回是tuple
current_date = date.strftime(date.today(), '%Y%m%d')
if row: # 空元组是没有记录的
cn = row[0]
date_, number = cn[:8], cn[8:]
if date_ == current_date:
number = str(int(number)+1).rjust(4, '0')
return '%s%s' % (date_, number)
return '%s0001' % current_date
return value
def _get_infodictlist_for_db(
cls, connection: BaseDatabaseWrapper, vendor: str, db_name: str,
schema_name: str) -> List[Dict[str, Any]]:
log.debug("Fetching/caching database structure (for database {}, "
"schema {})...".format(db_name, schema_name))
if db_name is None:
raise ValueError("Use '', not None, for a blank db_name")
if schema_name is None:
raise ValueError("Use '', not None, for a blank schema_name")
if vendor == VENDOR_MICROSOFT:
if not db_name:
raise ValueError("No db_name specified; required for MSSQL")
if not schema_name:
raise ValueError("No schema_name specified; required for MSSQL") # noqa
sql, args = cls._get_info_microsoft(db_name, [schema_name])
elif vendor == VENDOR_POSTGRESQL:
if db_name:
raise ValueError("db_name specified; must be '' for PostgreSQL") # noqa
if not schema_name:
raise ValueError("No schema_name specified; required for PostgreSQL") # noqa
sql, args = cls._get_info_postgres([schema_name])
elif vendor == VENDOR_MYSQL:
if db_name:
raise ValueError("db_name specified; must be '' for MySQL")
if not schema_name:
raise ValueError("No schema_name specified; required for MySQL") # noqa
sql, args = cls._get_info_mysql(db_and_schema_name=schema_name)
else:
raise ValueError(
"Don't know how to get metadata for "
"connection.vendor=='{}'".format(vendor))
# We execute this one directly, rather than using the Query class,
# since this is a system rather than a per-user query.
cursor = connection.cursor()
# log.debug("sql = {}, args = {}".format(sql, repr(args)))
cursor.execute(sql, args)
results = dictfetchall(cursor) # list of OrderedDicts
# log.debug("results = {}".format(repr(results)))
log.debug("... done")
return results
def check_supports_pg_trgm(connection: BaseDatabaseWrapper) -> bool:
"""Determine if trigram similarity support is present.
Attempts to run a query against the extensions table in PostgreSQL to
look for the pg_trgm extension. Failures assume a lack of support.
Args:
connection: The database connection.
Returns:
bool: True if trigram support is present.
"""
try:
with connection.cursor() as cursor:
cursor.execute("""
SELECT 1
FROM pg_extension
WHERE extname = 'pg_trgm' LIMIT 1;
""")
return bool(cursor.fetchone())
except DatabaseError:
return False
