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docs/api/models/mixins/relation-mixin.md

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+<a name="models.mixins.relation_mixin"></a>
+# models.mixins.relation\_mixin
+
+<a name="models.mixins.relation_mixin.RelationMixin"></a>
+## RelationMixin Objects
+
+```python
+class RelationMixin()
+```
+
+Used to return relation fields/names etc. from given model
+
+<a name="models.mixins.relation_mixin.RelationMixin.extract_db_own_fields"></a>
+#### extract\_db\_own\_fields
+
+```python
+ | @classmethod
+ | extract_db_own_fields(cls) -> Set
+```
+
+Returns only fields that are stored in the own database table, exclude all
+related fields.
+
+**Returns**:
+
+`(Set)`: set of model fields with relation fields excluded
+
+<a name="models.mixins.relation_mixin.RelationMixin.extract_related_fields"></a>
+#### extract\_related\_fields
+
+```python
+ | @classmethod
+ | extract_related_fields(cls) -> List
+```
+
+Returns List of ormar Fields for all relations declared on a model.
+List is cached in cls._related_fields for quicker access.
+
+**Returns**:
+
+`(List)`: list of related fields
+
+<a name="models.mixins.relation_mixin.RelationMixin.extract_related_names"></a>
+#### extract\_related\_names
+
+```python
+ | @classmethod
+ | extract_related_names(cls) -> Set
+```
+
+Returns List of fields names for all relations declared on a model.
+List is cached in cls._related_names for quicker access.
+
+**Returns**:
+
+`(List)`: list of related fields names
+
+<a name="models.mixins.relation_mixin.RelationMixin._extract_db_related_names"></a>
+#### \_extract\_db\_related\_names
+
+```python
+ | @classmethod
+ | _extract_db_related_names(cls) -> Set
+```
+
+Returns only fields that are stored in the own database table, exclude
+related fields that are not stored as foreign keys on given model.
+
+**Returns**:
+
+`(Set)`: set of model fields with non fk relation fields excluded
+
+<a name="models.mixins.relation_mixin.RelationMixin._exclude_related_names_not_required"></a>
+#### \_exclude\_related\_names\_not\_required
+
+```python
+ | @classmethod
+ | _exclude_related_names_not_required(cls, nested: bool = False) -> Set
+```
+
+Returns a set of non mandatory related models field names.
+
+For a main model (not nested) only nullable related field names are returned,
+for nested models all related models are returned.
+
+**Arguments**:
+
+- `nested (bool)`: flag setting nested models (child of previous one, not main one)
+
+**Returns**:
+
+`(Set)`: set of non mandatory related fields
+