# Override sorting behavior

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

Depending on the data source, not all fields may be sortable, or you may want to change how the native sorting works.

By using the `replaceFieldSorting` and `emulateFieldSorting` methods, you can change a single column's sorting behavior.

#### Substitution

You can also provide replacement sort clauses. In this example, we're telling Forest Admin "When a user sorts by full name, I want to sort by the last name, and then by the first name".

```php
use ForestAdmin\AgentPHP\DatasourceCustomizer\CollectionCustomizer;

$forestAgent->customizeCollection(
    'Customer',
    function (CollectionCustomizer $builder) {
        $builder->replaceFieldSorting(
        	'fullName',
        	[
        		['field' => 'lastName', 'ascending' => true],
        		['field' => 'firstName', 'ascending' => true],
            ]
        );
    }
);
```

Another very common reason is performance. For instance, with auto-incrementing ids, sorting by `creationDate` is equivalent to sorting by the primary key in reverse order.

Using sort substitution where needed can save you from adding many indexes to your database.

```php
use ForestAdmin\AgentPHP\DatasourceCustomizer\CollectionCustomizer;

$forestAgent->customizeCollection(
    'Customer',
    function (CollectionCustomizer $builder) {
        $builder->replaceFieldSorting('creationDate', [['field' => 'id', 'ascending' => false]]);
    }
);
```

#### Emulation

Sorting emulation allows making any field automatically sortable. It will sort records by lexicographical order. It is a convenient way to get things working quickly for Collections that have a low number of records (in the thousands at most).

{% hint style="warning" %}
This emulation forces the Agent to retrieve all the Collection records and compute the field values for each one of them. As a consequence, sorting emulation performance cost is **linear** with the number of records in the Collection, so **activate it sparingly and with great care**.
{% endhint %}

```php
use ForestAdmin\AgentPHP\DatasourceCustomizer\CollectionCustomizer;

$forestAgent->customizeCollection(
    'Customer',
    function (CollectionCustomizer $builder) {
        $builder->emulateFieldSorting('fullName');
    }
);
```