Passing an Array As A Function's Parameters Using (...$array)

Question

I'm trying pass an array as a function's parameters, and am having some trouble. Here's the function.

$stmt->bind_param();

I was researching this and found that you can use this:

$stmt->bind_param(...$values);

This worked well on my developmental server (PHP 7.0.0), but when I inputted it into another server (PHP 5.*), I got the following error:

syntax error, unexpected '.', expecting ')'

Upon further research, I tried:

call_user_func_array(array($stmt, 'bind_param'), $values);

and got this error:

call_user_func_array() expects parameter 1 to be a valid callback, first array member is not a valid class name or object

I know that I could just input the parameters and everything will work out fine, but I need the function to take any number of parameters (which is what led to the function idea).

Here's the function:

function updateId($id, $data){

    $mysqli = dbConnect::connect();

    $sm=array();
    $values=array();
    $dataString = array();

    foreach($data as $column=>$value){
        $dataString[] = ($column .'= ?');
        $values[] = $value;
        if(gettype($value)==="string"){
            $sm[] = 's';
        }elseif(gettype($value)==="integer"){
            $sm[] = 'i';
        }elseif(gettype($value)==="double"){
            $sm[] = 'd';
        }else{
            $sm[] = 'b';
        }
    }

    $dataString = implode(', ',$dataString);
    $sm = implode('',$sm);

    $prepString = "UPDATE $this->tablename SET $dataString WHERE id=$id";

    array_unshift($values, $sm);

    $stmt = $mysqli->prepare($prepString);
    $stmt->bind_param(...$values);
    $stmt->execute() or die($stmt->error);
    $stmt->close();
    $mysqli->close();

}

Maybe if you showed us some actual code you would get a better response. — RiggsFolly, Oct 05 '16 at 17:35
Seems self explanatory _first array member is not a valid class name or object_ — AbraCadaver, Oct 05 '16 at 17:37
I can provide that if that's helpful, but it works in my developmental server. All the errors point to that line. — Blaise, Oct 05 '16 at 17:38
There are many major differences between PHP7 and previous versions, but in order to be sure this is due to one of them it would be useful to see what we are actually talking about before we give any Glib answers — RiggsFolly, Oct 05 '16 at 17:40
Haha I have another one that is a little more adaptable... unfortunately, it has the same issues. :( — Blaise, Oct 05 '16 at 18:02
Could you `var_dump($stmt)` just before your attempt to `call_user_func_array`? It could be that it is `false`, meaning the statement failed. — trincot, Oct 05 '16 at 19:00
You can check by doing `echo $mysqli->error;`. What does it say? — trincot, Oct 05 '16 at 19:22
I'm getting this error currently: Parameter 2 to mysqli_stmt::bind_param() expected to be a reference, — Blaise, Oct 05 '16 at 19:28
OK, so you now have a valid `$stmt` object I assume. Next thing is to ensure that your `$values` array (at least the original values part) consists of references. I posted an answer about that. — trincot, Oct 05 '16 at 19:45

score 1 · Accepted Answer · answered Oct 05 '16 at 19:44

1

You are getting an error because you pass non-reference values to bind_param. You can use call_user_func_array, but you must make sure that the values you pass are references. This you can achieve as follows:

Change this:

$values[] = $value;

to this:

$values[] = &$data[$column];

And (like you already did) change this:

$stmt->bind_param(...$values);

into this:

call_user_func_array(array($stmt, 'bind_param'), $values);

answered Oct 05 '16 at 19:44

trincot

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Thank you so much. What's the difference between $values[] = $value; and $values[] = &$data[$column];? – Blaise Oct 05 '16 at 19:55
1

The difference is visible when you `var_dump` the array after the loop: with the changed code you see a `&` before each value, meaning it really are pointers (or addresses) referring to the actual value. This is what `bind_param` needs. I suppose it needs this for making it possible to deal with output parameters, which is not your case, but could be the case when calling stored procedures/functions. – trincot Oct 05 '16 at 20:06

Passing an Array As A Function's Parameters Using (...$array)

1 Answers1