对象的 array_only？

Well, array_unique() compares the string value of the elements:

Note: Two elements are considered equal if and only if (string) $elem1 === (string) $elem2 i.e. when the string representation is the same, the first element will be used.

So make sure to implement the __toString() method in your class and that it outputs the same value for equal roles, e.g.

class Role {
private $name;


//.....


public function __toString() {
return $this->name;
}


}

This would consider two roles as equal if they have the same name.

From here: http://php.net/manual/en/function.array-unique.php#75307

This one would work with objects and arrays also.

<?php
function my_array_unique($array, $keep_key_assoc = false)
{
$duplicate_keys = array();
$tmp         = array();


foreach ($array as $key=>$val)
{
// convert objects to arrays, in_array() does not support objects
if (is_object($val))
$val = (array)$val;


if (!in_array($val, $tmp))
$tmp[] = $val;
else
$duplicate_keys[] = $key;
}


foreach ($duplicate_keys as $key)
unset($array[$key]);


return $keep_key_assoc ? $array : array_values($array);
}
?>

This answer uses in_array() since the nature of comparing objects in PHP 5 allows us to do so. Making use of this object comparison behaviour requires that the array only contain objects, but that appears to be the case here.

$merged = array_merge($arr, $arr2);
$final  = array();


foreach ($merged as $current) {
if ( ! in_array($current, $final)) {
$final[] = $current;
}
}


var_dump($final);

array_unique works by casting the elements to a string and doing a comparison. Unless your objects uniquely cast to strings, then they won't work with array_unique.

Instead, implement a stateful comparison function for your objects and use array_filter to throw out things the function has already seen.

Here is a way to remove duplicated objects in an array:

<?php
// Here is the array that you want to clean of duplicate elements.
$array = getLotsOfObjects();


// Create a temporary array that will not contain any duplicate elements
$new = array();


// Loop through all elements. serialize() is a string that will contain all properties
// of the object and thus two objects with the same contents will have the same
// serialized string. When a new element is added to the $new array that has the same
// serialized value as the current one, then the old value will be overridden.
foreach($array as $value) {
$new[serialize($value)] = $value;
}


// Now $array contains all objects just once with their serialized version as string.
// We don't care about the serialized version and just extract the values.
$array = array_values($new);

You can also serialize first:

$unique = array_map( 'unserialize', array_unique( array_map( 'serialize', $array ) ) );

As of PHP 5.2.9 you can just use optional sort_flag SORT_REGULAR:

$unique = array_unique( $array, SORT_REGULAR );

array_unique works with an array of objects using SORT_REGULAR:

class MyClass {
public $prop;
}


$foo = new MyClass();
$foo->prop = 'test1';


$bar = $foo;


$bam = new MyClass();
$bam->prop = 'test2';


$test = array($foo, $bar, $bam);


print_r(array_unique($test, SORT_REGULAR));

Will print:

Array (
[0] => MyClass Object
(
[prop] => test1
)


[2] => MyClass Object
(
[prop] => test2
)
)

See it in action here: http://3v4l.org/VvonH#v529

Warning: it will use the "==" comparison, not the strict comparison ("===").

So if you want to remove duplicates inside an array of objects, beware that it will compare each object properties, not compare object identity (instance).

You can also use they array_filter function, if you want to filter objects based on a specific attribute:

//filter duplicate objects
$collection = array_filter($collection, function($obj)
{
static $idList = array();
if(in_array($obj->getId(),$idList)) {
return false;
}
$idList []= $obj->getId();
return true;
});

sane and fast way if you need to filter duplicated instances (i.e. "===" comparison) out of array and:

• you are sure what array holds only objects
• you dont need keys preserved

is:

//sample data
$o1 = new stdClass;
$o2 = new stdClass;
$arr = [$o1,$o1,$o2];


//algorithm
$unique = [];
foreach($arr as $o){
$unique[spl_object_hash($o)]=$o;
}
$unique = array_values($unique);//optional - use if you want integer keys on output

This is my way of comparing objects with simple properties, and at the same time receiving a unique collection:

class Role {
private $name;


public function __construct($name) {
$this->name = $name;
}


public function getName() {
return $this->name;
}
}


$roles = [
new Role('foo'),
new Role('bar'),
new Role('foo'),
new Role('bar'),
new Role('foo'),
new Role('bar'),
];


$roles = array_map(function (Role $role) {
return ['key' => $role->getName(), 'val' => $role];
}, $roles);


$roles = array_column($roles, 'val', 'key');


var_dump($roles);

Will output:

array (size=2)
'foo' =>
object(Role)[1165]
private 'name' => string 'foo' (length=3)
'bar' =>
object(Role)[1166]
private 'name' => string 'bar' (length=3)

If you have array of objects and you want to filter this collection to remove all duplicates you can use array_filter with anonymous function:

$myArrayOfObjects = $myCustomService->getArrayOfObjects();


// This is temporary array
$tmp = [];
$arrayWithoutDuplicates = array_filter($myArrayOfObjects, function ($object) use (&$tmp) {
if (!in_array($object->getUniqueValue(), $tmp)) {
$tmp[] = $object->getUniqueValue();
return true;
}
return false;
});

Important: Remember that you must pass $tmp array as reference to you filter callback function otherwise it will not work

If you have an indexed array of objects, and you want to remove duplicates by comparing a specific property in each object, a function like the remove_duplicate_models() one below can be used.

class Car {
private $model;


public function __construct( $model ) {
$this->model = $model;
}


public function get_model() {
return $this->model;
}
}


$cars = [
new Car('Mustang'),
new Car('F-150'),
new Car('Mustang'),
new Car('Taurus'),
];


function remove_duplicate_models( $cars ) {
$models = array_map( function( $car ) {
return $car->get_model();
}, $cars );


$unique_models = array_unique( $models );


return array_values( array_intersect_key( $cars, $unique_models ) );
}


print_r( remove_duplicate_models( $cars ) );

The result is:

Array
(
[0] => Car Object
(
[model:Car:private] => Mustang
)


[1] => Car Object
(
[model:Car:private] => F-150
)


[2] => Car Object
(
[model:Car:private] => Taurus
)


)

This is very simple solution:

$ids = array();


foreach ($relate->posts as $key => $value) {
if (!empty($ids[$value->ID])) { unset($relate->posts[$key]); }
else{ $ids[$value->ID] = 1; }
}

You can also make the array unique using a callback function (e.g. if you want to compare a property of the object or whatever method).

This is the generic function I use for this purpose:

/**
* Remove duplicate elements from an array by comparison callback.
*
* @param array $array : An array to eliminate duplicates by callback
* @param callable $callback : Callback accepting an array element returning the value to compare.
* @param bool $preserveKeys : Add true if the keys should be perserved (note that if duplicates eliminated the first key is used).
* @return array: An array unique by the given callback
*/
function unique(array $array, callable $callback, bool $preserveKeys = false): array
{
$unique = array_intersect_key($array, array_unique(array_map($callback, $array)));
return ($preserveKeys) ? $unique : array_values($unique);
}

Sample usage:

$myUniqueArray = unique($arrayToFilter,
static function (ExamQuestion $examQuestion) {
return $examQuestion->getId();
}
);

array_unique version for strict (===) comparison, preserving keys:

function array_unique_strict(array $array): array {
$result = [];
foreach ($array as $key => $item) {
if (!in_array($item, $result, true)) {
$result[$key] = $item;
}
}
return $result;
}

Usage:

class Foo {}
$foo1 = new Foo();
$foo2 = new Foo();
array_unique_strict( ['a' => $foo1, 'b' => $foo1, 'c' => $foo2] ); // ['a' => $foo1, 'c' => $foo2]