silverstripe-framework/docs/en/02_Developer_Guides/00_Model/03_Lists.md

title: Managing Lists
summary: The SS_List interface allows you to iterate through and manipulate a list of objects.

# Managing Lists

Whenever using the ORM to fetch records or navigate relationships you will receive an [SS_List](api:SilverStripe\ORM\SS_List) instance commonly as
either [DataList](api:SilverStripe\ORM\DataList) or [RelationList](api:SilverStripe\ORM\RelationList). This object gives you the ability to iterate over each of the results or
modify.

## Iterating over the list.

[SS_List](api:SilverStripe\ORM\SS_List) implements `IteratorAggregate`, allowing you to loop over the instance.

```php
	use SilverStripe\Security\Member;
	
    $members = Member::get();

    foreach($members as $member) {
        echo $member->Name;
    }
```

Or in the template engine:

```ss

    <% loop $Members %>
        <!-- -->
    <% end_loop %>
```

## Finding an item by value.

```php
    // $list->find($key, $value);

    //
    $members = Member::get();

    echo $members->find('ID', 4)->FirstName;
    // returns 'Sam'
```

## Maps

A map is an array where the array indexes contain data as well as the values. You can build a map from any list

```php
    $members = Member::get()->map('ID', 'FirstName');
    
    // $members = array(
    //    1 => 'Sam'
    //    2 => 'Sig'
    //    3 => 'Will'
    // );

```

This functionality is provided by the [Map](api:SilverStripe\ORM\Map) class, which can be used to build a map around any `SS_List`.

```php
    $members = Member::get();
    $map = new Map($members, 'ID', 'FirstName');
```

## Column

```php
    $members = Member::get();

    echo $members->column('Email');

    // returns array(
    //    'sam@silverstripe.com',
    //    'sig@silverstripe.com',
    //    'will@silverstripe.com'
    // );

```

## ArrayList

[ArrayList](api:SilverStripe\ORM\ArrayList) exists to wrap a standard PHP array in the same API as a database backed list.

```php
    $sam = Member::get()->byId(5);
    $sig = Member::get()->byId(6);

    $list = new ArrayList();
    $list->push($sam);
    $list->push($sig);

    echo $list->Count();
    // returns '2'

```

## API Documentation

* [SS_List](api:SilverStripe\ORM\SS_List)
* [RelationList](api:SilverStripe\ORM\RelationList)
* [DataList](api:SilverStripe\ORM\DataList)
* [ArrayList](api:SilverStripe\ORM\ArrayList)
* [Map](api:SilverStripe\ORM\Map)