Grouping lists in a template

[Andrea]

Hello. I'm new to both django and python. Been trying to figure out how to group items from  a model for hours now. 

This in an example code i made up to illustrate my problem:

# Models

class Book(models.Model):

    submitted_by = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='book_subby')

    submitted_date = models.DateField(auto_now=True)

    book_title = models.CharField(max_length=200)

    book_publisher = models.ForeignKey(Publishers)

class Publishers(models.Model):

    submitted_by = models.ForeignKey(settings.AUTH_USER_MODEL, related_name='publisher_subby')

    submitted_date = models.DateField(auto_now=True)

    book_publisher = models.CharField(max_length=200)

# View

def book_list(request):

    books = Book.objects.filter(submitted_by=request.user, submitted_date__lte=timezone.now()).order_by('submitted_date')

    return render(request, 'book/list_books.html', {

        'books': books 

        })

# Template list_books.html

{% for book in books %}

    <ul> {{ book.book_publisher }}

    <li> {{book.book_title }} </li>

{% endfor %}

This displays:

Publisher X

* Book A

Publisher Y

* Book B

Publisher X

* Book C

Publisher Y

* Book D

I want to display:

Publisher X

* Book A

* Book C

Publisher Y

* Book B

* Book D

I tried doing multiple for loops in the template, but couldn't make it work.

I would appreciate it alot if someone could nudge me in the right direction on how to solve this. 

Thanks, Andrea

[Daniel Roseman]

There are several ways of doing this. One is to sort by Publisher first: 

    books = Book.objects.filter(...).select_related('book_publisher').order_by('book_publisher__book_publisher', 'submitted_date')

and use the {% ifchanged %} tag to only print the publisher name when it changes:

{% for book in books %}

    {% ifchanged %} {{ book.book_publisher }} {% endif changed %}

    <li> {{book.book_title }} </li>

{% endfor %}

--

DR.

[Scot Hacker]

On Sunday, July 12, 2015 at 5:50:11 PM UTC-7, Andrea wrote:

Hello. I'm new to both django and python. Been trying to figure out how to group items from  a model for hours now. 

Check out the `regroup` template tag:

https://docs.djangoproject.com/en/1.8/ref/templates/builtins/#regroup

It can probably save you from writing custom code for this.

./s

[anotherdjangonewby]

Another approach would be to build a list of dictionaries based on the query and pass this to the template instead of the pure llst of books:

[{

publisher: 'Publisher X',

books: ['Book A', 'Book B']

}],....

So the logic remains in the code and not in the template.

Kai

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