Error – What Should Mage::throwException Do?

errorexceptionlogging

I'm sorry if this is a bleedingly obvious question. I think I am going crazy.

I have code that I know is stopping at a specific point. The file I am looking at is app/code/core/Mage/Downloadable/Helper/Download.php (NB. yes, I totally understand and agree that I should not be fiddling with core, but this is just my playing around in a locally installed Magento, and going to be reverted back afterwards)

The line that the code is breaking at is:

if (!isset($urlProp['scheme']) || strtolower($urlProp['scheme'] != 'http')) {
    Mage::throwException(Mage::helper('downloadable')->__('Invalid download URL scheme.'));
}

It is not getting past the Mage::throwException line. I know this because I am logging comments (to my own custom log file) before and after that line, and only the comments before that line are being logged.

My question is not why I am getting this specific error for this specific bit of code – but why I am not seeing the Invalid download URL scheme. error ANYWHERE. It is not appearing in my browser when the code is run, and it is not appearing in exception.log (that file actually does not exist in var/log – nor does system.log). Am I right in thinking that I should be seeing that error somewhere? It is making debugging very difficult!

Here's what I've done to try and get errors showing:

In System/Configuration/Advanced/Developer/Log Settings – Set "Enabled" to "Yes".
In index.php, I have got Mage::setIsDeveloperMode(true);
In index.php, I have got ini_set('display_errors', 1); I know this is working because if I force a syntax error, I get an error in browser.
In /errors, I have renamed local.xml.sample to local.xml (not sure what this one does but have seen it in a couple of articles to do with exception printing).
I have checked that var/log is writable. I know this is working because there is another custom log file that I am writing to successfully with Mage::log

Any ideas greatly welcomed! What should Mage::throwException actually be doing – printing in browser, or in exception.log, or both?

I am using Magento CE 1.9.0.1 on localhost (using a Mac with MAMP).

Best Answer

It throws an exception, nothing more, nothing less.

That means, any code higher up the stack may catch it and do whatever it decides to. Typically it's one or more of the following:

Mage::logException() (this is where it gets added to exception.log)
show an error message to the user
just move on
throw another exception

My guess is on (3) in your case. Get a debugger installed on your development system, set a breakpoint at the Mage::throwException() line and you will find out. And I actually highly recommend looking at the core. It's one of the best resources to learn Magento development.

Update:

if you see a page with something like "An error occured, please contact the store owner" and a long number, this is what Magento shows you for uncaught exceptions. You will find the exception message and stack trace logged in var/report/HERE_COMES_THE_NUMBER

Related Solutions

Magento – Magento system.log is filling up with errors

Answer for one of the errors, having run into it before...

line 55: $this->addItem('skin_css', $name, $params);

I'd start looking for a malformed line in your template layout local.xml, head.xml or page.xml

The Head.php block is being fed a configuration line with missing info.

Typical addCss type CSS load statements are as follows:

<action method="addCss"><stylesheet>css/widgets.css</stylesheet></action>

addItem statements have the ability to use parameters for conditional loading of either JavaScript or CSS.

Typical addItem type CSS load statements in layout xml files look like the following:

<action method="addItem"><type>skin_css</type><name>css/funky.css</name><params/><if>lt IE 8</if></action>

You need to tell it:

the type of addItem
relative path and name of file
conditional parameters

Magento then goes to your current active template skin folder, looks for the css folder and loads the file. Apparently the file name is bunged up in one of the lines which causes Head.php to choke.

I'd run grep from the command line and look for all addItem lines in in the layout folder in my currently active template (paying close attention to the CSS versions and then back up and look for layouts added by third party modules.

Invalid Argument Supplied for Foreach in Mage/Eav/Model/Entity/Collection/Abstract.php – Magento 1.8 Fix

I had the problem too and your comment hinted me to the right spot.

As you said the error comes from the public function joinTable() in app/code/core/Mage/Eav/Model/Entity/Collection/Abstract.php.

Unlike you I have used joinTable() in a Module of mine.

The head of that function says the following

 * @param string|array $table
 * @param string $bind
 * @param string|array $fields
 * @param null|array $cond
 * @param string $joinType
 * @return Mage_Eav_Model_Entity_Collection_Abstract
 */
public function joinTable($table, $bind, $fields = null, $cond = null, $joinType = 'inner')

Problem here is that $fields should not be of type string as said in the @param because it is used in a foreach loop.

I modified my call of joinTable() to not give a string, but an array with a string. No log entries so far.

My guess for you would be that some module uses joinTable and passes just a string for $fields. Are you able to debug into your code? That way you would have the stacktrace and could determine which modules fault that was.

EDIT:

I've looked further into it to anser your last questions:

"is it a bad one"

No. The join will still work, because later on, deep in call structure reachable from line 817 of Abstract.php there is a check if $fields (until then called $cols) is an array (/lib/Varien/Db/Select.php line 411) and if not will be converted into one for further processing (this is missing in Abstract.php).

"can it be ignored"

I'd say yes. It crams your log, but not disabling your project (at this point).

Best Answer

Update:

Related Solutions

Magento – Magento system.log is filling up with errors

Invalid Argument Supplied for Foreach in Mage/Eav/Model/Entity/Collection/Abstract.php – Magento 1.8 Fix

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