1from __future__ import annotations
 2
 3from typing import TYPE_CHECKING
 4
 5from plain.models.backends.base.validation import BaseDatabaseValidation
 6from plain.preflight import PreflightResult
 7
 8if TYPE_CHECKING:
 9    from plain.models.fields import Field
10
11
12class DatabaseValidation(BaseDatabaseValidation):
13    def preflight(self) -> list[PreflightResult]:
14        issues = super().preflight()
15        issues.extend(self._check_sql_mode())
16        return issues
17
18    def _check_sql_mode(self) -> list[PreflightResult]:
19        if not (
20            self.connection.sql_mode & {"STRICT_TRANS_TABLES", "STRICT_ALL_TABLES"}
21        ):
22            return [
23                PreflightResult(
24                    fix=f"{self.connection.display_name} Strict Mode is not set for the database connection. "
25                    f"{self.connection.display_name}'s Strict Mode fixes many data integrity problems in "
26                    f"{self.connection.display_name}, such as data truncation upon insertion, by "
27                    "escalating warnings into errors. It is strongly "
28                    "recommended you activate it.",
29                    id="mysql.strict_mode_not_enabled",
30                    warning=True,
31                )
32            ]
33        return []
34
35    def check_field_type(self, field: Field, field_type: str) -> list[PreflightResult]:
36        """
37        MySQL has the following field length restriction:
38        No character (varchar) fields can have a length exceeding 255
39        characters if they have a unique index on them.
40        MySQL doesn't support a database index on some data types.
41        """
42        errors = []
43        if (
44            field_type.startswith("varchar")
45            and field.primary_key
46            and (field.max_length is None or int(field.max_length) > 255)
47        ):
48            errors.append(
49                PreflightResult(
50                    fix=f"{self.connection.display_name} may not allow unique CharFields to have a max_length "
51                    "> 255.",
52                    obj=field,
53                    id="mysql.unique_charfield_max_length_too_long",
54                    warning=True,
55                )
56            )
57
58        return errors