Silverstripe DataObjects as Pages Part 2 tutorial-

问题:

I've been following Silverstripe DataObjects as Pages - Part 2: Using Model Admin and URL Segments to create a product catalogue tutorial on my localhost and running into a sidebar problem.

When I use the same method to create a sidebar as tutorial one, an error message shows on my site [User Error] Uncaught Exception: Object->__call(): the method 'categorypages' does not exist on 'Product'

This is the code I added to Product.php for sidebar to appear.

//Return the Title as a menu title
public function MenuTitle()
{
  return $this->Title;
}  

//Ensure that the DO shows up in menu (it is needed otherwise sidebar doesn't show when not logged in)

function canView()
{
 return $this->CategoryPages()->canView();
}

Does anyone know how to fix this problem? Thanks very much.

回答1:

have you tried $this->Categories()->First()->canView() ? reading the comments below it seems to me you're trying to call canView on the list of all of your related CategoryPage objects (ComponentSet)

[EDIT] as you mentioned in the comments below, you get an error now in the cms calling canView on a non-object. my guess is you haven't attached any Categories yet to some Product, therefore Categories()->First() returns NULL. please try:

function canView() {
  //always show this product for users with full administrative rights (see tab 'Security' in CMS
  if(Permission::check('ADMIN')) return true;
  //go and get all categories this product belongs to
  $categories = $this->Categories();
  //are there any categories?
  if($categories->Count() > 0) {
    //get the first category to see wheter it's viewable by the current user
    return $categories->First()->canView();
  } else {
    //product doesn't belong to any categories, so don't render it
    return false;
  }
}

i don't really get though why you implemented this canView check. does it really matter wheter a Product is already related to a category? otherwise, just return true; in your canView method.

回答2:

I haven't tried it myself, but taking a look at the comments you should change $Category = $this->CategoryPages()->First(); to $Category = $this->Categories()->First();

回答3:

The error would suggest to me that you do not have a has_one relationship on your Product class with the name 'CategoryPages'. The example in the tutorial has the following on the StaffMember class (note the StaffPage relationship):

//Relations
static $has_one = array (
    'StaffPage' => 'StaffPage',
    'Photo' => 'Image'
);

This is what is referenced in the example canView function ($this->StaffPage()):

function canView()
{
    return $this->StaffPage()->canView();
}

Do you have an equivalent relationship named 'CategoryPages' on your Product? You need to specify the relationship to the parent correctly.