Select only unique array values from this array

Question

I have the following variable $rows:

Array (

[0] => stdClass Object
    (
        [product_sku] => PCH20
    )

[1] => stdClass Object
    (
        [product_sku] => PCH20
    )

[2] => stdClass Object
    (
        [product_sku] => PCH19
    )

[3] => stdClass Object
    (
        [product_sku] => PCH19
    )

)

I need to create second array $second containing only unique values:

Array (

[0] => stdClass Object
    (
        [product_sku] => PCH20
    )

[1] => stdClass Object
    (
        [product_sku] => PCH19
    )

)

But when i run array_unique on $rows, i receive:

Catchable fatal error: Object of class stdClass could not be converted to string on line 191

By default, PHP will try to convert values to strings for comparison. Try specifying "default": `$result = array_unique($array, SORT_REGULAR);` — Aleks G, Jul 05 '12 at 08:26

score 25 · Answer 1 · answered Jul 05 '12 at 08:26

25

array_unique()

The optional second parameter sort_flags may be used to modify the sorting behavior using these values:

Sorting type flags:

SORT_REGULAR - compare items normally (don't change types)

SORT_NUMERIC - compare items numerically

SORT_STRING - compare items as strings

SORT_LOCALE_STRING - compare items as strings, based on the current locale.

Also note the changenotes below

5.2.10 Changed the default value of sort_flags back to SORT_STRING.

5.2.9 Added the optional sort_flags defaulting to SORT_REGULAR. Prior to 5.2.9, this function used to sort the array with SORT_STRING internally.

$values = array_unique($values, SORT_REGULAR);

answered Jul 05 '12 at 08:26

KingCrunch

128,817
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It should not be the accepted answer. The question says `But when i run array_unique on $rows, i receive:` which this question does not address. – Whitecat Feb 29 '16 at 06:44
1

@Whitecat `SORT_STRING` (the default) tries to cast the values to string, before it compares the values and that's where the error comes from. See https://3v4l.org/DeHIj That's what the manual excerpts try to tell you – KingCrunch Feb 29 '16 at 20:35
I see now, that is what the answer is saying but it is not clear to someone who does not understand PHP. – Whitecat Mar 01 '16 at 17:38

score 10 · Accepted Answer · answered Jul 05 '12 at 08:25

10

$uniques = array();
foreach ($array as $obj) {
    $uniques[$obj->product_sku] = $obj;
}

var_dump($uniques);

answered Jul 05 '12 at 08:25

deceze

510,633
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score 5 · Answer 3 · answered Jul 05 '12 at 08:27

5

The default behavior of function array_unique() is to treat the values inside as strings first. So what's happening is that PHP is attempting to turn your objects into strings (which is throwing the error).

You can modify your function call like this:

$uniqueArray = array_unique($rows, SORT_REGULAR);

This will compare values without changing their data type.

answered Jul 05 '12 at 08:27

Stegrex

4,004
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Sorry, I was just in the process of writing it... : / – Stegrex Jul 05 '12 at 08:39

score 0 · Answer 4 · edited May 22 '17 at 11:54

Please check below code, I hope this will be helpful to you.

$resultArray = uniqueAssocArray($actualArray, 'product_sku');

function uniqueAssocArray($array, $uniqueKey) 
{
   if (!is_array($array)) 
   {
     return array();
   }
   $uniqueKeys = array();
   foreach ($array as $key => $item) 
   {
     $groupBy=$item[$uniqueKey];
     if (isset( $uniqueKeys[$groupBy]))
     {
        //compare $item with $uniqueKeys[$groupBy] and decide if you 
        //want to use the new item
        $replace= false; 
     }
    else
    {
        $replace=true;
    }
    if ($replace) 
      $uniqueKeys[$groupBy] = $item;   
 }
 return $uniqueKeys;
}

Select only unique array values from this array

4 Answers4

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