more refactors in relations'

ormar/relations/utils.py

@@ -0,0 +1,44 @@
+from typing import TYPE_CHECKING, Tuple, Type
+from weakref import proxy
+
+import ormar
+from ormar.fields.foreign_key import ForeignKeyField
+from ormar.fields.many_to_many import ManyToManyField
+from ormar.relations import Relation
+
+if TYPE_CHECKING:  # pragma no cover
+    from ormar import Model
+
+
+def register_missing_relation(
+    parent: "Model", child: "Model", child_name: str
+) -> Relation:
+    ormar.models.expand_reverse_relationships(child.__class__)
+    name = parent.resolve_relation_name(parent, child)
+    field = parent.Meta.model_fields[name]
+    parent._orm._add_relation(field)
+    parent_relation = parent._orm._get(child_name)
+    return parent_relation
+
+
+def get_relations_sides_and_names(
+    to_field: Type[ForeignKeyField],
+    parent: "Model",
+    child: "Model",
+    child_name: str,
+    virtual: bool,
+) -> Tuple["Model", "Model", str, str]:
+    to_name = to_field.name
+    if issubclass(to_field, ManyToManyField):
+        child_name, to_name = (
+            child.resolve_relation_name(parent, child),
+            child.resolve_relation_name(child, parent),
+        )
+        child = proxy(child)
+    elif virtual:
+        child_name, to_name = to_name, child_name or child.get_name()
+        child, parent = parent, proxy(child)
+    else:
+        child_name = child_name or child.get_name() + "s"
+        child = proxy(child)
+    return parent, child, child_name, to_name