I get this error: "array_push() expects parameter 1 to be array, string given" even when the value is of type array

Question

I am trying to add a value to the end of an array. I am using:

array_push($this->_attributes["class"],$value);

Now I know that the first parameter has to be an array. Upon inspection :

var_dump($this->_attributes["class"]); die(0);
array_push($this->_attributes["class"],$value);

I can see that the value being passed in is indeed an array as it should be. I am not sure how or why I am getting a string being passed. The output of the var_dump look like such:

array (size=0)
    empty

Why or how is $this->_attributes["class"] being seen as a string and not an array?

Edit: If I invert the two lines like so:

array_push($this->_attributes["class"],$value);
var_dump($this->_attributes["class"]); die(0);

The var_dump looks like this:

array (size=1)
   0 => string 'btn' (length=3)

This is the expected output. If I remove the var_dump, I get a fatal error on the array_push again.

** Full Class Declaration** This is enough of the class I able building for this example:

class Tag
{
    protected $_attributes = array("class"=>array());

    public function setAttribute($attribute,$value)
    {
        if( $attribute === "class" ) {
            $this->setClassAttribute($value);
        }
        $this->_attributes[$attribute] = $value;
    }
    public function setClassAttribute($value)
    {
        if( is_array($value) ) {
            foreach ($value as $c) {
                $this->setClassAttribute($c);
            }
            return;
        }
        // var_dump($this->_attributes["class"]); die(0);
        array_push($this->_attributes["class"],$value);
        // var_dump($this->_attributes["class"]); die(0);
    }
}

To execute it:

$tag = new Tag();
$tag->setAttribute("class","btn");

Please provide a minimal piece of code with which we can reproduce this. Definition of $this->_attributes? — trincot
– trincot, Commented Dec 10, 2016 at 23:50
Your updated sample doesn't reproduce the issue. - edit: looks like you have to set twice to cause. — Kevin Stich
– Kevin Stich, Commented Dec 11, 2016 at 0:03
Try using $this->_attributes["class"][] = $value instead. It might work, and if not, then you will likely get a more descriptive error. — SeinopSys
– SeinopSys, Commented Dec 11, 2016 at 0:03
@HPierce I am using xdebug. But this is not the case. If I were to var_dump($this->_attributes) then I would get more of a result like you are talking about. I will add it in the question so it is more legible. — wesleywmd
– wesleywmd, Commented Dec 11, 2016 at 0:04
@SeinopSys $this->_attributes["class"][] = $value throw a [] operator not supported for strings. Which is essentially the same problem. — wesleywmd
– wesleywmd, Commented Dec 11, 2016 at 0:06

Kevin Stich · Accepted Answer · 2016-12-11 00:08:28Z

1

Your problem is here:

public function setAttribute($attribute,$value)
{
    if( $attribute === "class" ) {
        $this->setClassAttribute($value);
    }
    $this->_attributes[$attribute] = $value;
}

setClassAttribute is indeed setting the value to array("btn"). Afterwards, it's being overwritten by the line outside the statement. Try:

public function setAttribute($attribute,$value)
{
    if( $attribute === "class" ) {
        $this->setClassAttribute($value);
    } else {
        $this->_attributes[$attribute] = $value;
    }
}

REPL:

php > $tag = new Tag();
php > $tag->setAttribute("class","btn");
array(0) {
}
array(1) {
  [0]=>
  string(3) "btn"
}
php > $tag->setAttribute("class","btn");
string(3) "btn"

Warning: array_push() expects parameter 1 to be array, string given in php shell code on line 21
string(3) "btn"

answered Dec 11, 2016 at 0:08

Kevin Stich

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1 Comment

wesleywmd Over a year ago

After adding the else clause, the error goes away. Thank you.

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