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78 lines
2.2 KiB
Python
78 lines
2.2 KiB
Python
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# -*- coding: utf-8 -*-
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from typing import Optional, List, Iterable
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import abc
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from ...log import *
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from .Table import Table
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from .Column import Column
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from .DataType import DataType
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from .CompositeForeignKey import CompositeForeignKey
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class Schema(abc.ABC): # export
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def __init__(self) -> None:
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self.___tables: Optional[List[Table]] = None
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self.__foreign_keys: Optional[List[CompositeForeignKey]] = None
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@property
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def __tables(self):
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if self.___tables is None:
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ret = dict()
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for name in self._table_names():
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slog(WARNING, f'Caching metadata for table "{name}"')
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assert(isinstance(name, str))
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ret[name] = self._table(name)
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self.___tables = ret
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return self.___tables
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# ------ API to be implemented
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@abc.abstractmethod
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def _table_names(self) -> Iterable[str]:
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throw(ERR, "Called pure virtual base class method")
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return []
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@abc.abstractmethod
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def _table(self, name: str) -> Table:
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throw(ERR, "Called pure virtual base class method")
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return None # type: ignore
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@abc.abstractmethod
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def _foreign_keys(self) -> List[CompositeForeignKey]:
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pass
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# ------ API to be called
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@property
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def table_names(self) -> Iterable[str]:
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return self.__tables.keys()
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@property
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def tables(self) -> Iterable[Table]:
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return self.__tables.values()
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@property
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def foreign_key_constraints(self) -> List[CompositeForeignKey]:
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if self.__foreign_keys is None:
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self.__foreign_keys = self._foreign_keys()
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return self.__foreign_keys
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def table(self, name: str) -> Table:
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return self.__tables[name]
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def table_by_model_name(self, name: str, throw=False) -> Table:
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for table in self.__tables.values():
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if table.model_name == name:
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return table
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if throw:
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raise Exception(f'Table "{name}" not found in database metadata')
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return None # type: ignore
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def primary_keys(self, table_name: str) -> Iterable[str]:
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return self.__tables[table_name].primary_keys
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def columns(self, table_name: str) -> Iterable[Column]:
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return self.__tables[table_name].columns
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