1from __future__ import annotations
2
3from collections import namedtuple
4from typing import Any
5
6import sqlparse
7from MySQLdb.constants import FIELD_TYPE # type: ignore[import-untyped]
8
9from plain.models.backends.base.introspection import BaseDatabaseIntrospection
10from plain.models.backends.base.introspection import FieldInfo as BaseFieldInfo
11from plain.models.backends.base.introspection import TableInfo as BaseTableInfo
12from plain.models.indexes import Index
13from plain.utils.datastructures import OrderedSet
14
15FieldInfo = namedtuple(
16 "FieldInfo",
17 BaseFieldInfo._fields + ("extra", "is_unsigned", "has_json_constraint", "comment"),
18)
19InfoLine = namedtuple(
20 "InfoLine",
21 "col_name data_type max_len num_prec num_scale extra column_default "
22 "collation is_unsigned comment",
23)
24TableInfo = namedtuple("TableInfo", BaseTableInfo._fields + ("comment",))
25
26
27class DatabaseIntrospection(BaseDatabaseIntrospection):
28 data_types_reverse = {
29 FIELD_TYPE.BLOB: "TextField",
30 FIELD_TYPE.CHAR: "CharField",
31 FIELD_TYPE.DECIMAL: "DecimalField",
32 FIELD_TYPE.NEWDECIMAL: "DecimalField",
33 FIELD_TYPE.DATE: "DateField",
34 FIELD_TYPE.DATETIME: "DateTimeField",
35 FIELD_TYPE.DOUBLE: "FloatField",
36 FIELD_TYPE.FLOAT: "FloatField",
37 FIELD_TYPE.INT24: "IntegerField",
38 FIELD_TYPE.JSON: "JSONField",
39 FIELD_TYPE.LONG: "IntegerField",
40 FIELD_TYPE.LONGLONG: "BigIntegerField",
41 FIELD_TYPE.SHORT: "SmallIntegerField",
42 FIELD_TYPE.STRING: "CharField",
43 FIELD_TYPE.TIME: "TimeField",
44 FIELD_TYPE.TIMESTAMP: "DateTimeField",
45 FIELD_TYPE.TINY: "IntegerField",
46 FIELD_TYPE.TINY_BLOB: "TextField",
47 FIELD_TYPE.MEDIUM_BLOB: "TextField",
48 FIELD_TYPE.LONG_BLOB: "TextField",
49 FIELD_TYPE.VAR_STRING: "CharField",
50 }
51
52 def get_field_type(self, data_type: Any, description: Any) -> str:
53 field_type = super().get_field_type(data_type, description)
54 if "auto_increment" in description.extra:
55 if field_type == "BigIntegerField":
56 return "PrimaryKeyField"
57 if description.is_unsigned:
58 if field_type == "BigIntegerField":
59 return "PositiveBigIntegerField"
60 elif field_type == "IntegerField":
61 return "PositiveIntegerField"
62 elif field_type == "SmallIntegerField":
63 return "PositiveSmallIntegerField"
64 # JSON data type is an alias for LONGTEXT in MariaDB, use check
65 # constraints clauses to introspect JSONField.
66 if description.has_json_constraint:
67 return "JSONField"
68 return field_type
69
70 def get_table_list(self, cursor: Any) -> list[TableInfo]:
71 """Return a list of table and view names in the current database."""
72 cursor.execute(
73 """
74 SELECT
75 table_name,
76 table_type,
77 table_comment
78 FROM information_schema.tables
79 WHERE table_schema = DATABASE()
80 """
81 )
82 return [
83 TableInfo(row[0], {"BASE TABLE": "t", "VIEW": "v"}.get(row[1]), row[2])
84 for row in cursor.fetchall()
85 ]
86
87 def get_table_description(self, cursor: Any, table_name: str) -> list[FieldInfo]:
88 """
89 Return a description of the table with the DB-API cursor.description
90 interface."
91 """
92 json_constraints: set[Any] = set()
93 if (
94 self.connection.mysql_is_mariadb
95 and self.connection.features.can_introspect_json_field
96 ):
97 # JSON data type is an alias for LONGTEXT in MariaDB, select
98 # JSON_VALID() constraints to introspect JSONField.
99 cursor.execute(
100 """
101 SELECT c.constraint_name AS column_name
102 FROM information_schema.check_constraints AS c
103 WHERE
104 c.table_name = %s AND
105 LOWER(c.check_clause) =
106 'json_valid(`' + LOWER(c.constraint_name) + '`)' AND
107 c.constraint_schema = DATABASE()
108 """,
109 [table_name],
110 )
111 json_constraints = {row[0] for row in cursor.fetchall()}
112 # A default collation for the given table.
113 cursor.execute(
114 """
115 SELECT table_collation
116 FROM information_schema.tables
117 WHERE table_schema = DATABASE()
118 AND table_name = %s
119 """,
120 [table_name],
121 )
122 row = cursor.fetchone()
123 default_column_collation = row[0] if row else ""
124 # information_schema database gives more accurate results for some figures:
125 # - varchar length returned by cursor.description is an internal length,
126 # not visible length (#5725)
127 # - precision and scale (for decimal fields) (#5014)
128 # - auto_increment is not available in cursor.description
129 cursor.execute(
130 """
131 SELECT
132 column_name, data_type, character_maximum_length,
133 numeric_precision, numeric_scale, extra, column_default,
134 CASE
135 WHEN collation_name = %s THEN NULL
136 ELSE collation_name
137 END AS collation_name,
138 CASE
139 WHEN column_type LIKE '%% unsigned' THEN 1
140 ELSE 0
141 END AS is_unsigned,
142 column_comment
143 FROM information_schema.columns
144 WHERE table_name = %s AND table_schema = DATABASE()
145 """,
146 [default_column_collation, table_name],
147 )
148 field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()}
149
150 cursor.execute(
151 f"SELECT * FROM {self.connection.ops.quote_name(table_name)} LIMIT 1"
152 )
153
154 def to_int(i: Any) -> Any:
155 return int(i) if i is not None else i
156
157 fields = []
158 for line in cursor.description:
159 info = field_info[line[0]]
160 fields.append(
161 FieldInfo(
162 *line[:2],
163 to_int(info.max_len) or line[2],
164 to_int(info.max_len) or line[3],
165 to_int(info.num_prec) or line[4],
166 to_int(info.num_scale) or line[5],
167 line[6],
168 info.column_default,
169 info.collation,
170 info.extra,
171 info.is_unsigned,
172 line[0] in json_constraints,
173 info.comment,
174 )
175 )
176 return fields
177
178 def get_sequences(
179 self, cursor: Any, table_name: str, table_fields: tuple[Any, ...] = ()
180 ) -> list[dict[str, Any]]:
181 for field_info in self.get_table_description(cursor, table_name):
182 if "auto_increment" in field_info.extra:
183 # MySQL allows only one auto-increment column per table.
184 return [{"table": table_name, "column": field_info.name}]
185 return []
186
187 def get_relations(self, cursor: Any, table_name: str) -> dict[str, tuple[str, str]]:
188 """
189 Return a dictionary of {field_name: (field_name_other_table, other_table)}
190 representing all foreign keys in the given table.
191 """
192 cursor.execute(
193 """
194 SELECT column_name, referenced_column_name, referenced_table_name
195 FROM information_schema.key_column_usage
196 WHERE table_name = %s
197 AND table_schema = DATABASE()
198 AND referenced_table_name IS NOT NULL
199 AND referenced_column_name IS NOT NULL
200 """,
201 [table_name],
202 )
203 return {
204 field_name: (other_field, other_table)
205 for field_name, other_field, other_table in cursor.fetchall()
206 }
207
208 def get_storage_engine(self, cursor: Any, table_name: str) -> str:
209 """
210 Retrieve the storage engine for a given table. Return the default
211 storage engine if the table doesn't exist.
212 """
213 cursor.execute(
214 """
215 SELECT engine
216 FROM information_schema.tables
217 WHERE
218 table_name = %s AND
219 table_schema = DATABASE()
220 """,
221 [table_name],
222 )
223 result = cursor.fetchone()
224 if not result:
225 return self.connection.features._mysql_storage_engine
226 return result[0]
227
228 def _parse_constraint_columns(
229 self, check_clause: str, columns: set[str]
230 ) -> OrderedSet:
231 check_columns: OrderedSet = OrderedSet()
232 statement = sqlparse.parse(check_clause)[0]
233 tokens = (token for token in statement.flatten() if not token.is_whitespace)
234 for token in tokens:
235 if (
236 token.ttype == sqlparse.tokens.Name
237 and self.connection.ops.quote_name(token.value) == token.value
238 and token.value[1:-1] in columns
239 ):
240 check_columns.add(token.value[1:-1])
241 return check_columns
242
243 def get_constraints(
244 self, cursor: Any, table_name: str
245 ) -> dict[str, dict[str, Any]]:
246 """
247 Retrieve any constraints or keys (unique, pk, fk, check, index) across
248 one or more columns.
249 """
250 constraints: dict[str, dict[str, Any]] = {}
251 # Get the actual constraint names and columns
252 name_query = """
253 SELECT kc.`constraint_name`, kc.`column_name`,
254 kc.`referenced_table_name`, kc.`referenced_column_name`,
255 c.`constraint_type`
256 FROM
257 information_schema.key_column_usage AS kc,
258 information_schema.table_constraints AS c
259 WHERE
260 kc.table_schema = DATABASE() AND
261 c.table_schema = kc.table_schema AND
262 c.constraint_name = kc.constraint_name AND
263 c.constraint_type != 'CHECK' AND
264 kc.table_name = %s
265 ORDER BY kc.`ordinal_position`
266 """
267 cursor.execute(name_query, [table_name])
268 for constraint, column, ref_table, ref_column, kind in cursor.fetchall():
269 if constraint not in constraints:
270 constraints[constraint] = {
271 "columns": OrderedSet(),
272 "primary_key": kind == "PRIMARY KEY",
273 "unique": kind in {"PRIMARY KEY", "UNIQUE"},
274 "index": False,
275 "check": False,
276 "foreign_key": (ref_table, ref_column) if ref_column else None,
277 }
278 if self.connection.features.supports_index_column_ordering:
279 constraints[constraint]["orders"] = []
280 constraints[constraint]["columns"].add(column)
281 # Add check constraints.
282 if self.connection.features.can_introspect_check_constraints:
283 unnamed_constraints_index = 0
284 columns = {
285 info.name for info in self.get_table_description(cursor, table_name)
286 }
287 if self.connection.mysql_is_mariadb:
288 type_query = """
289 SELECT c.constraint_name, c.check_clause
290 FROM information_schema.check_constraints AS c
291 WHERE
292 c.constraint_schema = DATABASE() AND
293 c.table_name = %s
294 """
295 else:
296 type_query = """
297 SELECT cc.constraint_name, cc.check_clause
298 FROM
299 information_schema.check_constraints AS cc,
300 information_schema.table_constraints AS tc
301 WHERE
302 cc.constraint_schema = DATABASE() AND
303 tc.table_schema = cc.constraint_schema AND
304 cc.constraint_name = tc.constraint_name AND
305 tc.constraint_type = 'CHECK' AND
306 tc.table_name = %s
307 """
308 cursor.execute(type_query, [table_name])
309 for constraint, check_clause in cursor.fetchall():
310 constraint_columns = self._parse_constraint_columns(
311 check_clause, columns
312 )
313 # Ensure uniqueness of unnamed constraints. Unnamed unique
314 # and check columns constraints have the same name as
315 # a column.
316 if set(constraint_columns) == {constraint}:
317 unnamed_constraints_index += 1
318 constraint = f"__unnamed_constraint_{unnamed_constraints_index}__"
319 constraints[constraint] = {
320 "columns": constraint_columns,
321 "primary_key": False,
322 "unique": False,
323 "index": False,
324 "check": True,
325 "foreign_key": None,
326 }
327 # Now add in the indexes
328 cursor.execute(f"SHOW INDEX FROM {self.connection.ops.quote_name(table_name)}")
329 for table, non_unique, index, colseq, column, order, type_ in [
330 x[:6] + (x[10],) for x in cursor.fetchall()
331 ]:
332 if index not in constraints:
333 constraints[index] = {
334 "columns": OrderedSet(),
335 "primary_key": False,
336 "unique": not non_unique,
337 "check": False,
338 "foreign_key": None,
339 }
340 if self.connection.features.supports_index_column_ordering:
341 constraints[index]["orders"] = []
342 constraints[index]["index"] = True
343 constraints[index]["type"] = (
344 Index.suffix if type_ == "BTREE" else type_.lower()
345 )
346 constraints[index]["columns"].add(column)
347 if self.connection.features.supports_index_column_ordering:
348 constraints[index]["orders"].append("DESC" if order == "D" else "ASC")
349 # Convert the sorted sets to lists
350 for constraint in constraints.values():
351 constraint["columns"] = list(constraint["columns"])
352 return constraints