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ssh://git.janware.com/srv/git/janware/proj/jw-python
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Jan Lindemann
17ab47e96a
jw.db.schema is a set of classes meant as an interface to describe a database schema. Signed-off-by: Jan Lindemann <jan@janware.com>
75 lines
2.2 KiB
Python
75 lines
2.2 KiB
Python
# -*- coding: utf-8 -*-
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from typing import Optional, Any
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import abc
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from ...log import *
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from .DataType import DataType
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class Column(abc.ABC): # export
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def __init__(self, table, name, data_type: DataType):
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self.__name: str = name
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self.__table: Any = table
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self.__is_nullable: Optional[bool] = None
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self.__is_null_insertible: Optional[bool] = None
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self.__is_primary_key: Optional[bool] = None
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self.__default_value: Optional[Any] = None
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self.__default_value_cached: bool = False
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self.__is_auto_increment: Optional[bool] = None
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self.__data_type: DataType = data_type
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def __repr__(self):
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return f'{self.__table.name}.{self.__name}: {self.__data_type}'
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@property
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def name(self) -> str:
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return self.__name
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@property
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def data_type(self):
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return self.__data_type
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@property
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def table(self) -> str:
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return self.__table
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@property
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def is_nullable(self) -> bool:
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if self.__is_nullable is None:
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self.__is_nullable = self.__name in self.__table.nullable_columns
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return self.__is_nullable
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@property
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def is_null_insertible(self):
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if self.__is_null_insertible is None:
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ret = False
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if self.is_nullable:
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ret = True
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elif self.is_auto_increment:
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ret = True
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elif self.default_value is not None:
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ret = True
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self.__is_null_insertible = ret
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return self.__is_null_insertible
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@property
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def is_primary_key(self) -> bool:
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if self.__is_primary_key is None:
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self.__is_primary_key = self.__name in self.__table.primary_keys
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return self.__is_primary_key
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@property
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def is_auto_increment(self) -> bool:
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if self.__is_auto_increment is None:
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self.__is_auto_increment = self.__name in self.__table.auto_increment_columns
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return self.__is_auto_increment
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@property
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def default_value(self) -> Optional[Any]:
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if self.__default_value_cached is False:
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self.__default_value = self.__table.column_default(self.name)
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self.__default_value_cached = True
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return self.__default_value
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