Changes:

- fix queryset copy accidentally initializing table
- improve sql debug property
- update docs

docs/queries/queries.md

@@ -1097,7 +1097,7 @@ The pendant in a model are `identifying_clauses`.
 query = Model.query.filter(id=1)
 # ensures that the db connection doesn't drop during operation
 async with query.database as database:
- # when using joins a exist subquery is generated
+ # when using joins a subquery is generated
  expression = query.table.select().where(await query.build_where_clause())
  # as generic sql
  print(str(expression))
@@ -1124,6 +1124,10 @@ async with model.database as database:
 If you want raw sql see the print statements. You most probably want a dialect specific sql string for non-basic
 sql types because otherwise some features are not supported or cause warnings.
 
+## Debugging
+
+QuerySet contains a cached debug property named `sql` which contains the QuerySet as query with inserted blanks.
+
 [model]: ../models.md
 [managers]: ../managers.md
 [lambda statements](https://docs.sqlalchemy.org/en/20/core/sqlelement.html#sqlalchemy.sql.expression.lambda_stmt)

edgy/core/db/models/mixins/row.py

@@ -251,6 +251,9 @@ async def __set_prefetch(
  ) -> None:
  model_key = ()
  if related._is_finished:
+ # when force_rollback
+ # we can only bake after all rows are retrieved
+ # this is why it is here
  await related.init_bake(type(model))
  model_key = model.create_model_key()
  if model_key in related._baked_results:

edgy/core/db/querysets/base.py

@@ -189,7 +189,7 @@ def _clone(self) -> "QuerySet":
  """
  queryset = self.__class__(
  self.model_class,
- database=self.database,
+ database=getattr(self, "_database", None),
  filter_clauses=self.filter_clauses,
  select_related=self._select_related,
  prefetch_related=self._prefetch_related,
@@ -336,9 +336,8 @@ def _build_tables_join_from_relationship(
  """
 
  # How does this work?
- # First we build a transitions table with a dependency, so we find a path
- # Secondly we check if a select_related path is joining a table from the set in an opposite direction
- # If yes, we mark the transition for a full outer join (dangerous, there could be side-effects)
+ # First we build a transitions tree (maintable is root) by providing optionally a dependency.
+ # Resolving a dependency automatically let's us resolve the tree.
  # At last we iter through the transisitions and build their dependencies first
  # We pop out the transitions so a path is not taken 2 times
 
@@ -362,7 +361,14 @@ def _build_tables_join_from_relationship(
  former_table = maintable
  former_transition = None
  prefix: str = ""
+ # prefix which expands m2m fields
  _select_prefix: str = ""
+ # False (default): add prefix regularly.
+ # True: skip adding existing prefix to tables_and_models and skip adding the next field to the
+ # public prefix.
+ # string: add a custom prefix instead of the calculated one and skip adding the next field to the
+ # public prefix.
+
  injected_prefix: Union[bool, str] = False
  model_database: Optional[Database] = self.database
  while select_path:
@@ -424,6 +430,8 @@ def _build_tables_join_from_relationship(
  table = model_class.table_schema(self.active_schema)
  table = table.alias(hash_tablekey(tablekey=table.key, prefix=prefix))
 
+ # it is guranteed that former_table is either root and has a key or is an unique join node
+ # except there would be a hash collision which is very unlikely
  transition_key = (get_table_key_or_name(former_table), table.name, field_name)
  if transition_key in transitions:
  # can not provide new informations
@@ -1041,14 +1049,16 @@ class QuerySet(BaseQuerySet):
  QuerySet object used for query retrieving. Public interface
  """
 
+ async def _sql_helper(self) -> Any:
+ async with self.database:
+ return (await self.as_select()).compile(
+ self.database.engine, compile_kwargs={"literal_binds": True}
+ )
+
  @cached_property
  def sql(self) -> str:
- """Get SQL select query as string."""
- return str(
- run_sync(self.as_select()).compile(
- compile_kwargs={"literal_binds": True},
- )
- )
+ """Get SQL select query as string with inserted blanks. For debugging only!"""
+ return str(run_sync(self._sql_helper()))
 
  def filter(
  self,