# Polymorphic relationships

{% hint style="success" %}
This is the official documentation of the `forestadmin/laravel-forestadmin` v2+ and `forestadmin/symfony-forestadmin` PHP agents.
{% endhint %}

### Enable polymorphic support

Forest admin can interact with polymorphic relations by enabling the `polymorphic` option on the datasource instance.

```php
return static function () {
    $defaultDB = config('database.default');
    $forestAgent = app()->make(AgentFactory::class);

    $forestAgent->addDatasource(
        // set the second parameter to true to enable polymorphic relations
        new EloquentDatasource(config('database.connections.' . $defaultDB), true),
    );
};
```

### Tips

The `id field` and the `type field` of the relationship are still shown. You can use them to create segment, [hide them from the agent](/developer-guide-agents-php/agent-customization/fields/import-rename-remove.md#renaming-and-removing-fields-and-relations) or through the front-end configuration.

### Limitations

#### Collections

**Remove collection**

When using the [remove collection customization](/developer-guide-agents-php/data-sources/getting-started/partial-imports.md), it's important to note a limitation regarding collections that are potential targets of polymorphic relationships. If you attempt to delete a collection that is referenced in a polymorphic relationship, an exception will be thrown with the following message:

```
Cannot remove {CollectionName} because it's a potential target of polymorphic relation {InverseRelationName}.
```

This limitation exists to prevent corruption of data relationships that depend on this collection in a polymorphic context. Before attempting deletion, ensure that the collection you want to delete is not used as a target in such a relationship before attempting the deletion.

**Rename Collection**

The [rename collection customization](/developer-guide-agents-php/data-sources/getting-started/naming-conflicts.md) also imposes a restriction on collections involved in polymorphic relationships. If you attempt to rename a collection that is the target of a polymorphic relationship, an exception will be thrown with the following message:

```
Cannot rename collection {CurrentName} because it's a target of a polymorphic relation '{ForeignCollectionName}.{InverseRelationName}'.
```

This limitation ensures the integrity of polymorphic relationships in your data model. Before renaming a collection, verify that it is not involved in such polymorphic relationships to avoid errors.

#### Fields

**Remove field**

When using the [remove field customization](/developer-guide-agents-php/agent-customization/fields/import-rename-remove.md#renaming-and-removing-fields-and-relations), it's important to note a limitation concerning fields involved in the polymorphic relationships (`foreign_key_type` and `foreign_key_id`). If you attempt to delete a field that is used in a polymorphic relationship, an exception will be thrown with the following message:

```
Cannot remove field {CollectionName}.{FieldName}, because it's implied in a polymorphic relation '{CollectionName}.{PolymorphicRelationName}'.
```

This limitation is in place to ensure the proper functioning of the polymorphic relationship. Before deleting a field, ensure that the field you want to delete is not used as a foreign key or type field in any polymorphic relationship.

**Rename field**

When using the [rename field customization](/developer-guide-agents-php/agent-customization/fields/import-rename-remove.md#renaming-and-removing-fields-and-relations), it's important to be aware of a limitation concerning fields involved in polymorphic relationships (`foreign_key_type` and `foreign_key_id`). If you attempt to rename a field that is used in a polymorphic relationship, an exception will be thrown with the following message:

```
Cannot rename '{CollectionName}.{FieldName}', because it's implied in a polymorphic relation '{CollectionName}.{PolymorphicRelationName}'.
```

This limitation is in place to ensure the proper functioning of polymorphic relationship. Before renaming a field, ensure that the field you want to rename is not used as a as foreign key or type field of a polymorphic relationship.

**Computed field**

When using [computed fields](/developer-guide-agents-php/agent-customization/fields/computed.md), a list of `dependency` fields is required. Theses fields can travels '\*toOne' relationships using ':'. However, due to the unpredictable target collection of polymorphic relationship, they cannot be used as dependencies for computed fields; an error will be thrown with the following message:

```
Dependencies over a polymorphic relations({CollectionName}.{PolymorphicRelationName}) are forbidden.
```

Another limitation exists with computed fields when they are used as `reference field`. Due to the unpredictable target collection of the polymorphic relationships, computed fields cannot be evaluated over polymorphic relations. If used as a reference field, it will not be displayed on the front-end.

When computed fields are not evaluated over polymorphic relationships, a `debug` log is generated with the following message:

```
Cannot compute computed fields over polymorphic relation {CollectionName}.{PolymorphicRelationName}.
```

#### Search (extended)

When searching within a collection that contains a polymorphic relationship, [extended searches](/developer-guide-agents-php/agent-customization/search.md#search-modes) will not search through the polymorphic relationships. This behavior is designed to prevent excessive resource consumption and delays in SQL queries. A `debug` log will appear to alert you about this behavior with the following message:

```
We're not searching through {CollectionName}.{PolymorphicRelationName} because it's a polymorphic relation. You can override the default search behavior with 'replace_search'.
```

And a link leading to the [replace search documentation](/developer-guide-agents-php/agent-customization/search.md#customization). If you understand the implications and still want to search through polymorphic relations, you can follow the [replace search documentation](/developer-guide-agents-php/agent-customization/search.md#customization) to override the default search behavior.


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.forestadmin.com/developer-guide-agents-php/data-sources/provided-data-sources/eloquent/polymorphic-relationships.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.