Conatum
4229fe8b18
Add `LEQ` condition type. Ensure that batch updates don't fire with nothing to update. Add `cast_row` to `update_many` for handling typed `NULL`s.
284 lines
8.9 KiB
Python
284 lines
8.9 KiB
Python
from __future__ import annotations
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import contextlib
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from cachetools import LRUCache
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from typing import Mapping
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from utils.lib import DotDict
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from .connection import conn
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from .queries import insert, insert_many, select_where, update_where, upsert, delete_where, update_many
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# Global cache of interfaces
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tables: Mapping[str, Table] = DotDict()
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class Table:
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"""
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Transparent interface to a single table structure in the database.
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Contains standard methods to access the table.
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Intended to be subclassed to provide more derivative access for specific tables.
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"""
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conn = conn
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queries = DotDict()
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def __init__(self, name, attach_as=None):
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self.name = name
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tables[attach_as or name] = self
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def select_where(self, *args, **kwargs):
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with self.conn:
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return select_where(self.name, *args, **kwargs)
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def select_one_where(self, *args, **kwargs):
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rows = self.select_where(*args, **kwargs)
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return rows[0] if rows else None
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def update_where(self, *args, **kwargs):
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with self.conn:
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return update_where(self.name, *args, **kwargs)
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def delete_where(self, *args, **kwargs):
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with self.conn:
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return delete_where(self.name, *args, **kwargs)
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def insert(self, *args, **kwargs):
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with self.conn:
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return insert(self.name, *args, **kwargs)
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def insert_many(self, *args, **kwargs):
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with self.conn:
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return insert_many(self.name, *args, **kwargs)
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def update_many(self, *args, **kwargs):
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with self.conn:
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return update_many(self.name, *args, **kwargs)
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def upsert(self, *args, **kwargs):
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with self.conn:
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return upsert(self.name, *args, **kwargs)
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def save_query(self, func):
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"""
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Decorator to add a saved query to the table.
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"""
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self.queries[func.__name__] = func
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class Row:
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__slots__ = ('table', 'data', '_pending')
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conn = conn
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def __init__(self, table, data, *args, **kwargs):
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super().__setattr__('table', table)
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self.data = data
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self._pending = None
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@property
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def rowid(self):
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return self.table.id_from_row(self.data)
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def __repr__(self):
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return "Row[{}]({})".format(
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self.table.name,
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', '.join("{}={!r}".format(field, getattr(self, field)) for field in self.table.columns)
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)
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def __getattr__(self, key):
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if key in self.table.columns:
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if self._pending and key in self._pending:
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return self._pending[key]
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else:
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return self.data[key]
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else:
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raise AttributeError(key)
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def __setattr__(self, key, value):
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if key in self.table.columns:
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if self._pending is None:
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self.update(**{key: value})
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else:
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self._pending[key] = value
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else:
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super().__setattr__(key, value)
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@contextlib.contextmanager
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def batch_update(self):
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if self._pending:
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raise ValueError("Nested batch updates for {}!".format(self.__class__.__name__))
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self._pending = {}
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try:
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yield self._pending
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finally:
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if self._pending:
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self.update(**self._pending)
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self._pending = None
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def _refresh(self):
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row = self.table.select_one_where(self.table.dict_from_id(self.rowid))
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if not row:
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raise ValueError("Refreshing a {} which no longer exists!".format(type(self).__name__))
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self.data = row
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def update(self, **values):
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rows = self.table.update_where(values, **self.table.dict_from_id(self.rowid))
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self.data = rows[0]
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@classmethod
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def _select_where(cls, _extra=None, **conditions):
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return select_where(cls._table, **conditions)
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@classmethod
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def _insert(cls, **values):
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return insert(cls._table, **values)
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@classmethod
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def _update_where(cls, values, **conditions):
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return update_where(cls._table, values, **conditions)
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class RowTable(Table):
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__slots__ = (
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'name',
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'columns',
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'id_col',
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'multi_key',
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'row_cache'
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)
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conn = conn
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def __init__(self, name, columns, id_col, use_cache=True, cache=None, cache_size=1000, **kwargs):
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super().__init__(name, **kwargs)
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self.name = name
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self.columns = columns
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self.id_col = id_col
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self.multi_key = isinstance(id_col, tuple)
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self.row_cache = (cache or LRUCache(cache_size)) if use_cache else None
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def id_from_row(self, row):
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if self.multi_key:
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return tuple(row[key] for key in self.id_col)
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else:
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return row[self.id_col]
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def dict_from_id(self, rowid):
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if self.multi_key:
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return dict(zip(self.id_col, rowid))
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else:
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return {self.id_col: rowid}
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# Extend original Table update methods to modify the cached rows
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def insert(self, *args, **kwargs):
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data = super().insert(*args, **kwargs)
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if self.row_cache is not None:
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self.row_cache[self.id_from_row(data)] = Row(self, data)
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return data
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def insert_many(self, *args, **kwargs):
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data = super().insert_many(*args, **kwargs)
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if self.row_cache is not None:
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for data_row in data:
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cached_row = self.row_cache.get(self.id_from_row(data_row), None)
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if cached_row is not None:
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cached_row.data = data_row
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return data
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def update_where(self, *args, **kwargs):
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data = super().update_where(*args, **kwargs)
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if self.row_cache is not None:
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for data_row in data:
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cached_row = self.row_cache.get(self.id_from_row(data_row), None)
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if cached_row is not None:
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cached_row.data = data_row
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return data
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def update_many(self, *args, **kwargs):
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data = super().update_many(*args, **kwargs)
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if self.row_cache is not None:
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for data_row in data:
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cached_row = self.row_cache.get(self.id_from_row(data_row), None)
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if cached_row is not None:
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cached_row.data = data_row
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return data
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def delete_where(self, *args, **kwargs):
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data = super().delete_where(*args, **kwargs)
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if self.row_cache is not None:
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for data_row in data:
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self.row_cache.pop(self.id_from_row(data_row), None)
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return data
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def upsert(self, *args, **kwargs):
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data = super().upsert(*args, **kwargs)
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if self.row_cache is not None:
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rowid = self.id_from_row(data)
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cached_row = self.row_cache.get(rowid, None)
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if cached_row is not None:
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cached_row.data = data
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else:
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self.row_cache[rowid] = Row(self, data)
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return data
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# New methods to fetch and create rows
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def _make_rows(self, *data_rows):
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"""
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Create or retrieve Row objects for each provided data row.
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If the rows already exist in cache, updates the cached row.
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"""
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if self.row_cache is not None:
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rows = []
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for data_row in data_rows:
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rowid = self.id_from_row(data_row)
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cached_row = self.row_cache.get(rowid, None)
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if cached_row is not None:
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cached_row.data = data_row
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row = cached_row
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else:
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row = Row(self, data_row)
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self.row_cache[rowid] = row
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rows.append(row)
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else:
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rows = [Row(self, data_row) for data_row in data_rows]
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return rows
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def create_row(self, *args, **kwargs):
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data = self.insert(*args, **kwargs)
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return self._make_rows(data)[0]
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def fetch_rows_where(self, *args, **kwargs):
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# TODO: Handle list of rowids here?
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data = self.select_where(*args, **kwargs)
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return self._make_rows(*data)
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def fetch(self, rowid):
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"""
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Fetch the row with the given id, retrieving from cache where possible.
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"""
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row = self.row_cache.get(rowid, None) if self.row_cache is not None else None
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if row is None:
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rows = self.fetch_rows_where(**self.dict_from_id(rowid))
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row = rows[0] if rows else None
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return row
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def fetch_or_create(self, rowid=None, **kwargs):
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"""
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Helper method to fetch a row with the given id or fields, or create it if it doesn't exist.
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"""
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if rowid is not None:
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row = self.fetch(rowid)
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else:
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data = self.select_where(**kwargs)
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row = self._make_rows(data[0])[0] if data else None
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if row is None:
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creation_kwargs = kwargs
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if rowid is not None:
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creation_kwargs.update(self.dict_from_id(rowid))
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row = self.create_row(**creation_kwargs)
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return row
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