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ormar/docs/api/fields/many-to-many.md

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<a name="fields.many_to_many"></a>
# fields.many\_to\_many
<a name="fields.many_to_many.populate_m2m_params_based_on_to_model"></a>
#### populate\_m2m\_params\_based\_on\_to\_model
```python
populate_m2m_params_based_on_to_model(to: Type["Model"], nullable: bool) -> Tuple[Any, Any]
```
Based on target to model to which relation leads to populates the type of the
pydantic field to use and type of the target column field.
**Arguments**:
- `to (Model class)`: target related ormar Model
- `nullable (bool)`: marks field as optional/ required
**Returns**:
`(tuple with target pydantic type and target col type)`: Tuple[List, Any]
<a name="fields.many_to_many.ManyToMany"></a>
#### ManyToMany
```python
ManyToMany(to: "ToType", through: "ToType", *, name: str = None, unique: bool = False, virtual: bool = False, **kwargs: Any, ,) -> Any
```
Despite a name it's a function that returns constructed ManyToManyField.
This function is actually used in model declaration
(as ormar.ManyToMany(ToModel, through=ThroughModel)).
Accepts number of relation setting parameters as well as all BaseField ones.
**Arguments**:
- `to (Model class)`: target related ormar Model
- `through (Model class)`: through model for m2m relation
- `name (str)`: name of the database field - later called alias
- `unique (bool)`: parameter passed to sqlalchemy.ForeignKey, unique flag
- `virtual (bool)`: marks if relation is virtual.
It is for reversed FK and auto generated FK on through model in Many2Many relations.
- `kwargs (Any)`: all other args to be populated by BaseField
**Returns**:
`(ManyToManyField)`: ormar ManyToManyField with m2m relation to selected model
<a name="fields.many_to_many.ManyToManyField"></a>
## ManyToManyField Objects
```python
class ManyToManyField(ForeignKeyField, ormar.QuerySetProtocol, ormar.RelationProtocol)
```
Actual class returned from ManyToMany function call and stored in model_fields.
<a name="fields.many_to_many.ManyToManyField.get_source_related_name"></a>
#### get\_source\_related\_name
```python
| @classmethod
| get_source_related_name(cls) -> str
```
Returns name to use for source relation name.
For FK it's the same, differs for m2m fields.
It's either set as `related_name` or by default it's field name.
**Returns**:
`(str)`: name of the related_name or default related name.
<a name="fields.many_to_many.ManyToManyField.default_target_field_name"></a>
#### default\_target\_field\_name
```python
| @classmethod
| default_target_field_name(cls) -> str
```
Returns default target model name on through model.
**Returns**:
`(str)`: name of the field
<a name="fields.many_to_many.ManyToManyField.default_source_field_name"></a>
#### default\_source\_field\_name
```python
| @classmethod
| default_source_field_name(cls) -> str
```
Returns default target model name on through model.
**Returns**:
`(str)`: name of the field
<a name="fields.many_to_many.ManyToManyField.has_unresolved_forward_refs"></a>
#### has\_unresolved\_forward\_refs
```python
| @classmethod
| has_unresolved_forward_refs(cls) -> bool
```
Verifies if the filed has any ForwardRefs that require updating before the
model can be used.
**Returns**:
`(bool)`: result of the check
<a name="fields.many_to_many.ManyToManyField.evaluate_forward_ref"></a>
#### evaluate\_forward\_ref
```python
| @classmethod
| evaluate_forward_ref(cls, globalns: Any, localns: Any) -> None
```
Evaluates the ForwardRef to actual Field based on global and local namespaces
**Arguments**:
- `globalns (Any)`: global namespace
- `localns (Any)`: local namespace
**Returns**:
`(None)`: None