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import re
from .base import FIELD_TYPE
from django.db.backends import BaseDatabaseIntrospection, FieldInfo
from django.utils.encoding import force_text
foreign_key_re = re.compile(r"\sCONSTRAINT `[^`]*` FOREIGN KEY \(`([^`]*)`\) REFERENCES `([^`]*)` \(`([^`]*)`\)")
class DatabaseIntrospection(BaseDatabaseIntrospection):
data_types_reverse = {
FIELD_TYPE.BLOB: 'TextField',
FIELD_TYPE.CHAR: 'CharField',
FIELD_TYPE.DECIMAL: 'DecimalField',
FIELD_TYPE.NEWDECIMAL: 'DecimalField',
FIELD_TYPE.DATE: 'DateField',
FIELD_TYPE.DATETIME: 'DateTimeField',
FIELD_TYPE.DOUBLE: 'FloatField',
FIELD_TYPE.FLOAT: 'FloatField',
FIELD_TYPE.INT24: 'IntegerField',
FIELD_TYPE.LONG: 'IntegerField',
FIELD_TYPE.LONGLONG: 'BigIntegerField',
FIELD_TYPE.SHORT: 'IntegerField',
FIELD_TYPE.STRING: 'CharField',
FIELD_TYPE.TIME: 'TimeField',
FIELD_TYPE.TIMESTAMP: 'DateTimeField',
FIELD_TYPE.TINY: 'IntegerField',
FIELD_TYPE.TINY_BLOB: 'TextField',
FIELD_TYPE.MEDIUM_BLOB: 'TextField',
FIELD_TYPE.LONG_BLOB: 'TextField',
FIELD_TYPE.VAR_STRING: 'CharField',
}
def get_table_list(self, cursor):
"Returns a list of table names in the current database."
cursor.execute("SHOW TABLES")
return [row[0] for row in cursor.fetchall()]
def get_table_description(self, cursor, table_name):
"""
Returns a description of the table, with the DB-API cursor.description interface."
"""
# varchar length returned by cursor.description is an internal length,
# not visible length (#5725), use information_schema database to fix this
cursor.execute("""
SELECT column_name, character_maximum_length FROM information_schema.columns
WHERE table_name = %s AND table_schema = DATABASE()
AND character_maximum_length IS NOT NULL""", [table_name])
length_map = dict(cursor.fetchall())
# Also getting precision and scale from information_schema (see #5014)
cursor.execute("""
SELECT column_name, numeric_precision, numeric_scale FROM information_schema.columns
WHERE table_name = %s AND table_schema = DATABASE()
AND data_type='decimal'""", [table_name])
numeric_map = dict([(line[0], tuple([int(n) for n in line[1:]])) for line in cursor.fetchall()])
cursor.execute("SELECT * FROM %s LIMIT 1" % self.connection.ops.quote_name(table_name))
return [FieldInfo(*((force_text(line[0]),)
+ line[1:3]
+ (length_map.get(line[0], line[3]),)
+ numeric_map.get(line[0], line[4:6])
+ (line[6],)))
for line in cursor.description]
def _name_to_index(self, cursor, table_name):
"""
Returns a dictionary of {field_name: field_index} for the given table.
Indexes are 0-based.
"""
return dict([(d[0], i) for i, d in enumerate(self.get_table_description(cursor, table_name))])
def get_relations(self, cursor, table_name):
"""
Returns a dictionary of {field_index: (field_index_other_table, other_table)}
representing all relationships to the given table. Indexes are 0-based.
"""
my_field_dict = self._name_to_index(cursor, table_name)
constraints = self.get_key_columns(cursor, table_name)
relations = {}
for my_fieldname, other_table, other_field in constraints:
other_field_index = self._name_to_index(cursor, other_table)[other_field]
my_field_index = my_field_dict[my_fieldname]
relations[my_field_index] = (other_field_index, other_table)
return relations
def get_key_columns(self, cursor, table_name):
"""
Returns a list of (column_name, referenced_table_name, referenced_column_name) for all
key columns in given table.
"""
key_columns = []
cursor.execute("""
SELECT column_name, referenced_table_name, referenced_column_name
FROM information_schema.key_column_usage
WHERE table_name = %s
AND table_schema = DATABASE()
AND referenced_table_name IS NOT NULL
AND referenced_column_name IS NOT NULL""", [table_name])
key_columns.extend(cursor.fetchall())
return key_columns
def get_indexes(self, cursor, table_name):
cursor.execute("SHOW INDEX FROM %s" % self.connection.ops.quote_name(table_name))
# Do a two-pass search for indexes: on first pass check which indexes
# are multicolumn, on second pass check which single-column indexes
# are present.
rows = list(cursor.fetchall())
multicol_indexes = set()
for row in rows:
if row[3] > 1:
multicol_indexes.add(row[2])
indexes = {}
for row in rows:
if row[2] in multicol_indexes:
continue
indexes[row[4]] = {'primary_key': (row[2] == 'PRIMARY'), 'unique': not bool(row[1])}
return indexes
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