Default image in magento extension

Question

I'm trying to develop a module to show a list of categories' name and image, my controller send an array contains names and images url to my block, i want to show a default image if no image assign to any category:

-so my questions where is the better place to check if the image url is null and assign the default image url (in controller or in block).

-my second part of the question where to save this image in media or in skin folder as im planning to use it in defferent themes and i dont want to change the code every time i move it

Answer 1

Load the category and check for a valid image url

    $_category = Mage::getModel('catalog/category')->load($_categoryId);
    $_catImgUrl = $_category->getImageUrl()
    if (!$_catImgUrl) {
      $_catImgUrl=Mage::getBaseUrl('media').'yourmodule/default-image.png'
    }

I would create a media folder for your module and store the images in media/yourmodule.