On Jan 12, 2008 10:59 AM, Darthmahon <[EMAIL PROTECTED]> wrote:
>
> Hey,
>
> I want to check if the current item I am printing in one list is also
> available in another list. Basically I have a list of books and I want
> to check if the user already has a particular book in their profile so
> that instead of it saying "Add Book", it says "Remove Book".
>
> At the moment I am trying something like this:
>
> ################
> # File: custom_filters.py
> ################
> @register.filter
> def IN(value,arg): return value in arg
> ################
>
> ################
> # File: /books/views.py
> ################
> {% for book in books %}
> {% if book.id|IN:user_profile.books.all %}
> <p>Remove Book</p>
> {% else %}
> <p>Add Book</p>
> {% endif %}
> {% endfor %}
> ################
>
This is really your template file, right, not views.py?
> user_profile has a many-to-many field relationship so that it gets a
> list of all the books the user has.
>
> Basically, I get an error that tells me:
>
> Invalid Filter: 'IN'
>
> Is there a better way of checking if the current item in the for loop
> is present in another list?
In my experience "Invalid" whatever from template processing usually means I
forgot to load my custom template tags/filters. So did you include a {%
load custom_filters %} in your template file?
Karen
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