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https://github.com/silverstripe/silverstripe-framework
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95 lines
1.8 KiB
Markdown
95 lines
1.8 KiB
Markdown
title: Managing Lists
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summary: The SS_List interface allows you to iterate through and manipulate a list of objects.
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# Managing Lists
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Whenever using the ORM to fetch records or navigate relationships you will receive an [api:SS_List] instance commonly as
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either [api:DataList] or [api:RelationList]. This object gives you the ability to iterate over each of the results or
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modify.
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## Iterating over the list.
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[api:SS_List] implements `IteratorAggregate`, allowing you to loop over the instance.
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:::php
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$members = Member::get();
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foreach($members as $member) {
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echo $member->Name;
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}
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Or in the template engine:
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:::ss
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<% loop $Members %>
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<!-- -->
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<% end_loop %>
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## Finding an item by value.
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:::php
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// $list->find($key, $value);
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//
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$members = Member::get();
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echo $members->find('ID', 4)->FirstName;
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// returns 'Sam'
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## Maps
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A map is an array where the array indexes contain data as well as the values. You can build a map from any list
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:::php
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$members = Member::get()->map('ID', 'FirstName');
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// $members = array(
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// 1 => 'Sam'
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// 2 => 'Sig'
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// 3 => 'Will'
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// );
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This functionality is provided by the [api:Map] class, which can be used to build a map around any `SS_List`.
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:::php
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$members = Member::get();
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$map = new Map($members, 'ID', 'FirstName');
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## Column
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:::php
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$members = Member::get();
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echo $members->column('Email');
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// returns array(
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// 'sam@silverstripe.com',
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// 'sig@silverstripe.com',
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// 'will@silverstripe.com'
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// );
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## ArrayList
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[api:ArrayList] exists to wrap a standard PHP array in the same API as a database backed list.
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:::php
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$sam = Member::get()->byId(5);
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$sig = Member::get()->byId(6);
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$list = new ArrayList();
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$list->push($sam);
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$list->push($sig);
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echo $list->Count();
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// returns '2'
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## API Documentation
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* [api:SS_List]
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* [api:RelationList]
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* [api:DataList]
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* [api:ArrayList]
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* [api:Map]
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