debugging an undefined variable, Magento PHP

Question

I am using the theme "Love Fashion" for magento, however this is just for info if anyone has come across the same problem with this theme before.

I get the following error Notice: Undefined variable: deal. The error occurs on two lines, 50 and 61 - however the error shows up twice on line 50 eg.:

Notice: Undefined variable: deal on line 50
Notice: Undefined variable: deal on line 50
Notice: Undefined variable: deal on line 61

This happens for the following code (starting on line 49, ending on line 67):

public function addFilter($filterName,$filtervalue,$condition='='){
        if ($deal instanceof Sm_Deal_Model_Deal){
            $deal = $deal->getId();
        }
        if (!$this->_joinedFields){
            $this->joinFields();
        }
         $this->getSelect()->where('deal.'.$filterName.' '.$condition.' ?', $filtervalue);
        return $this;
    }

public function OrderbyAdd($orderName,$ordervalue){
        if ($deal instanceof Sm_Deal_Model_Deal){
            $deal = $deal->getId();
        }
        $this->getSelect()->order('deal.'.$orderName.' '.$ordervalue);

        return $this;
    }

So my question is, how do i fix the undefined variable in this case?

For example, i use the following code earlier in the same document, but this doesn't give any errors: (starting at line 26, ending at line 47)

public function addDealFilter($deal){
    if ($deal instanceof Sm_Deal_Model_Deal){
        $deal = $deal->getId();
    }
    if (!$this->_joinedFields){
        $this->joinFields();
    }
    $this->getSelect()->where('related.deal_id = ?', $deal);
    return $this;
}

public function joinFieldsdeal(){

        $this->getSelect()->join(
            array('deal' => $this->getTable('deal/deal')),
            'deal.entity_id = related.deal_id',
            array('deal.end_date','deal.start_date','deal.name')
        );
        $this->_joinedFields = true;

    return $this;
}

The question is not a duplicate of "Reference: What is variable scope, which variables are accessible from where and what are “undefined variable” errors?" as this simply explains the basic of functions - which is not the case here.

possible duplicate of [Reference: What is variable scope, which variables are accessible from where and what are "undefined variable" errors?](http://stackoverflow.com/questions/16959576/reference-what-is-variable-scope-which-variables-are-accessible-from-where-and) — IMSoP, Apr 28 '15 at 20:07
Hi IMSoP - it might be the same sort of problem, but the question you link to, only defines the basic of functions, which I already know. The code i listed above, i don't understand the scoping of, as this is not as clear to me, as the scoping you linked to. — Patrick, Apr 28 '15 at 20:19
Given the scoping rules explained in the linked answer, where do you think `$deal` will come from on the line highlighted by the Notice? — IMSoP, Apr 28 '15 at 20:22
Ah, so the `function addFilter($filterName,$filtervalue,$condition='=')` isn't defining $deal within the addFilter() function, and therefore it cannot be found by the if statement?? — Patrick, Apr 28 '15 at 20:28
Bingo! The reason the second example works is that $deal is the name of a parameter, so has already been defined at the very start of that function. — IMSoP, Apr 28 '15 at 20:30
I see! Thanks! Quick question: would i be able to just write for example `function addFilter($deal,$filterName,$filtervalue,$condition='=')` or would i have to know, at what position in the addFilter() function $deal is defined whereever the function is used? — Patrick, Apr 28 '15 at 20:35
If you add it as a parameter, it takes on whatever value you give it when you call that function - every time you call the function, you have to decide what it is that you want that parameter to be. The whole point of scope is that $deal can mean different things in different places. Consider this: `function foo($deal) { var_dump($deal); } $deal='hello'; foo($deal); foo(42); $old_deal=$deal; $deal++; foo($deal); foo($old_deal);` etc. — IMSoP, Apr 28 '15 at 20:41

score 1 · Accepted Answer · answered Apr 28 '15 at 21:00

In both of those functions (addFilter, OrderbyAdd), the offending bit of code is here

if ($deal instanceof Sm_Deal_Model_Deal){
    $deal = $deal->getId();
}

The only variables available in a function are

The function parameters ($filterName,$filtervalue,$condition and $orderName,$ordervalue), respectively.
Variables defined in the function
Any global variables

The variable $deal is none of these. It is, as the error message says, not defined. The clause

if ($deal instanceof Sm_Deal_Model_Deal){
    $deal = $deal->getId();
}

Has no practical impact on your program. The variable $deal is never an instance of Sm_Deal_Model_Deal because the variable $deal does not exist. You can remove the entire if clause from your code and you won't change how your system behaves (except to remove that Notices)

That said -- it's not clear why this code is here in the first place. Someone added it for a reason -- or possibly removed portions of each function that defined $deal. It'd be worth checking these files against a clean version of your theme.

debugging an undefined variable, Magento PHP

1 Answers1