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

# 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 = [
//    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 [
//    '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'
```

## Related Lessons
* [Lists and pagination](https://www.silverstripe.org/learn/lessons/v4/lists-and-pagination-1)

## 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)