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ssh://git.janware.com/srv/git/janware/proj/jw-python
synced 2026-01-15 09:53:32 +01:00
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>
78 lines
2.3 KiB
Python
78 lines
2.3 KiB
Python
# -*- coding: utf-8 -*-
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from typing import Optional, List, Any
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from .ColumnSet import ColumnSet
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from .SingleForeignKey import SingleForeignKey
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class CompositeForeignKey: # export
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def __init__(self, child_col_set: ColumnSet, parent_col_set: ColumnSet): # TODO: Implement alternative ways to construct
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def __table(s):
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ret = None
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for c in s:
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if ret is None:
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ret = c.table
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else:
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assert(ret == c.table)
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assert(ret is not None)
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return ret
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self.__child_col_set = child_col_set
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self.__parent_col_set = parent_col_set
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self.__child_table = __table(child_col_set)
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self.__parent_table = __table(parent_col_set)
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assert(len(self.__child_col_set) == len(self.__parent_col_set))
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self.__len = len(self.__child_col_set)
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self.__column_relations: Optional[List[SingleForeignKey]] = None
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def __table_rel_str(self):
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return f'{self.__child_table.name} => {self.__parent_table.name}'
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def __cols_rel_str(self, child, parent):
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return f'{child.name} -> {parent.name}'
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def __len__(self):
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return self.__len
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def __iter__(self):
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yield from self.column_relations
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def __repr__(self):
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ret = self.__table_rel_str()
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ret += '|| ' + ' | '.join([self.__cols_rel_str(rel.child_col, rel.parent_col) for rel in self.column_relations])
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return ret
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def __eq__(self, rhs):
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if rhs.__child_col_set != self.__child_col_set:
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return False
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if rhs.__parent_col_set != self.__parent_col_set:
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return False
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return True
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@property
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def child_table(self) -> Any:
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return self.__child_table
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@property
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def parent_table(self) -> Any:
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return self.__parent_table
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@property
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def child_columns(self) -> ColumnSet:
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return self.__child_col_set
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@property
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def parent_columns(self) -> ColumnSet:
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return self.__parent_col_set
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@property
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def column_relations(self) -> List[Any]:
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ret = []
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if self.__column_relations is None:
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for i in range(0, self.__len):
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ret.append(SingleForeignKey(self.__child_col_set[i], self.__parent_col_set[i]))
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self.__column_relations = ret
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return self.__column_relations
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