我想知道是否有办法在Twig中创建函数（或其他），所以我可以访问for循环中的下一个和前一个元素。像这样：
{% for i in items %}
{% if i == previous() %}
<p>yes</p>
{% endif %}
{% endfor %}
更新
目标是我有很多支票，比如
if current.name == prev.name
do somethig
else
do another thing
与下一个
相同在我编写排序过滤器之后问题变得更大了，现在很明显
{% set items = allitems|sortbyname %}
{% for item in items %}
{{ item.name }}
{% endfor %}
此处的项目按排序顺序
和
{% for item in items %}
{{ items[loop.index0].name }}
{% endfor %}
这里他们不是
所以我不能使用类似的东西：
if item.name == items [loop.index0 + 1] .name用于访问下一个元素
我无法弄清楚如何克服这些问题:(你能帮帮我吗？
答案 0 :(得分：3)
树枝上没有previous()这样的东西
您可以查看loop variables
在您的情况下，解决方法是构建自定义迭代器 这是一个例子
/**
* Previous Next Iterator adds two methods to the ArrayIterator
*
* -> getPreviousElement() To get the previous element of the iterator
* -> getNextElement() To get the next element of the iterator
*
* These methods will not affect the internal pointer
*/
class PreviousNextIterator extends ArrayIterator
{
protected $indexKeys = array();
protected $keyIndexs = array();
protected $elements = array();
protected $dirty = true;
/**
* Constructor
*
* @param array $array Input Array
* @param integer $flags Flags
*/
public function __construct($array = array(), $flags = 0)
{
parent::__construct($array, $flags);
$this->load();
}
/**
* Helper class to self create from an ArrayIterator
*
* @param ArrayIterator $iterator ArrayIterator to fetch
* @return PreviousNextIterator New self instance
*/
public static function createFromIterator(ArrayIterator $iterator)
{
return new self($iterator->getArrayCopy());
}
/**
* Get the previous element of the iterator
*
* @return mixed Previous element
*/
public function getPreviousElement()
{
$index = $this->getIndexKey($this->key());
if (--$index < 0) {
return;
}
$key = $this->getKeyIndex($index);
return $this->elements[$key];
}
/**
* Get the next element of the iterator
*
* @return mixed Next element
*/
public function getNextElement()
{
$index = $this->getIndexKey($this->key());
if (++$index >= $this->count()) {
return;
}
$key = $this->getKeyIndex($index);
return $this->elements[$key];
}
/**
* Loads up the keys
*
* $this->elements
* Contains the copy of the iterator array
* Eg: [ 'a' => $fooInstance1, 'b' => $fooInstance2 ...]
*
* $this->keyIndexs
* Contains the keys indexed numerically
* Eg: [ 0 => 'a', 1 => 'b' ...]
*
* $this->indexKeys
* Contains the indexes of the keys
* Eg: [ 'a' => 0, 'b' => 1 ...]
*/
protected function load()
{
if (!$this->isDirty()) {
return;
}
$this->elements = $this->getArrayCopy();
$this->keyIndexs = array_keys($this->elements);
$this->indexKeys = array_flip($this->keyIndexs);
$this->dirty = false;
}
/**
* Checks whether the loader is dirty
*
* @return boolean
*/
protected function isDirty()
{
return $this->dirty;
}
/**
* Get the Index of a given key
*
* @param string $key Key name
* @return integer Key's index
*/
protected function getIndexKey($key)
{
$this->load();
return array_key_exists($key, $this->indexKeys)
? $this->indexKeys[$key]
: null;
}
/**
* Get the key of a given index
*
* @param integer $index Key's index
* @return string Key name
*/
protected function getKeyIndex($index)
{
$this->load();
return array_key_exists($index, $this->keyIndexs)
? $this->keyIndexs[$index]
: null;
}
/**
* Following methods overrides default methods which alters the iterator
* in order to create a "Dirty state" which will force the reload
*
* You just need to write them all so as to get a complete working class
*/
public function append($value)
{
$this->dirty = true;
return parent::append($value);
}
}
此迭代器添加了两个方法getPreviousElement和getNextElement
class Foo
{
protected $name;
public function __construct($name)
{
$this->name = $name;
}
}
$array = array(
'a' => new Foo('bar'),
'b' => 42,
'c' => new Foo('foobaz'),
'czz' => 'bleh',
);
$iterator = new PreviousNextIterator($array);
foreach ($iterator as $key => $value) {
echo '--- PREVIOUS ---', PHP_EOL;
var_dump($iterator->getPreviousElement());
echo '--- CURRENT ---', PHP_EOL;
var_dump($value);
echo '--- NEXT ---', PHP_EOL;
var_dump($iterator->getNextElement());
echo '----------------', PHP_EOL, PHP_EOL;
}
<强>输出
--- PREVIOUS ---
NULL
--- CURRENT ---
object(Foo)#1 (1) {
["name":protected]=>
string(3) "bar"
}
--- NEXT ---
int(42)
----------------
--- PREVIOUS ---
object(Foo)#1 (1) {
["name":protected]=>
string(3) "bar"
}
--- CURRENT ---
int(42)
--- NEXT ---
object(Foo)#2 (1) {
["name":protected]=>
string(6) "foobaz"
}
----------------
--- PREVIOUS ---
int(42)
--- CURRENT ---
object(Foo)#2 (1) {
["name":protected]=>
string(6) "foobaz"
}
--- NEXT ---
string(4) "bleh"
----------------
--- PREVIOUS ---
object(Foo)#2 (1) {
["name":protected]=>
string(6) "foobaz"
}
--- CURRENT ---
string(4) "bleh"
--- NEXT ---
NULL
----------------
在您的过滤器示例中，返回迭代器，只需替换
return $iterator;
通过
return PreviousNextIterator::createFromIterator($iterator);
然后在TWIG中使用它
{% for i in items %}
{% if i == items.previousElement %}
<p>Yes</p>
{% endif %}
{% if i == items.nextElement %}
<p>Same Next</p>
{% endif %}
{% endfor %}
答案 1 :(得分：1)
像
这样的东西{% set previous_name = '' %}
{% for i in items %}
{% if i.name == previous_name %}
<p>yes</p>
{% else %}
<p>no</p>
{% endif %}
{% set previous_name = i.name %}
{% endfor %}
来源：http://twig.sensiolabs.org/doc/templates.html#setting-variables
答案 2 :(得分：1)
有一种简单的方法可以在 twig 中做到这一点，无需扩展：
{% for i in iterable_set %}
{% if (loop.index0 + 1) < iterable_set|length %}
{% set next = iterable_set[loop.index0 + 1] %}{# next #}
{% endif %}
{% if (loop.index0 - 1) >= 0 %}
{% set prev = iterable_set[loop.index0 - 1] %}{# previous #}
{% endif %}
{% endfor %}
答案 3 :(得分：0)
我不确定你想达到什么目标，但试试这个：
services:
acme.twig.acme_extension:
class: Acme\DemoBundle\Twig\AcmeExtension
tags:
- { name: twig.extension }
和
namespace Acme\DemoBundle\Twig;
class AcmeExtension extends \Twig_Extension
{
public function getFilters()
{
return array(
new \Twig_SimpleFilter('filterX', array($this, 'filterX')),
);
}
public function filterX(array $items)
{
$result = $prev = null;
foreach ($items as $value) {
if ($value === $prev && $prev !== null) {
$result = 'yes';
}
$prev = $value;
}
return $result;
}
public function getName()
{
return 'acme_extension';
}
}
在你的树枝模板中：
{{ items|filterX}}
答案 4 :(得分：0)
一种获取数组中上一个和下一个项目的可能解决方案：
{% set prev = {} %}
{% set next = {} %}
{% set lastwascurrent = false %}
{% set last = {} %}
{% for item in items %}
{% if lastwascurrent %}
{% set next = item %}
{% set lastwascurrent = false %}
{% endif %}
{% if item.id == 'some_id' %}
{% set lastwascurrent = true %}
{% set prev = last %}
{% endif %}
{% set last = item %}
{% endfor %}