CODEWITHSUNDEEP
djangodjango-modelsjinja2
Mario Rossi
Mario Rossi

Reputation: 127

Django display Foreign Key reference in Template

I'm trying to develop an application in django. I have a general Publication table that may or may be not linked to a Project model.

Here is some code :

Project

class Project(models.Model):
    title = models.CharField(max_length=254)
    abstract = models.CharField(max_length=254)
    link = models.URLField()

    def __str__(self):
        return self.title

Publication

class Publication(models.Model):
    id = models.IntegerField(primary_key=True)
    title = models.CharField(max_length=254)
    authors_string = models.CharField(max_length=254, default='')
    project = models.ForeignKey(Project, on_delete=models.DO_NOTHING, blank=True, null=True)

    def __str__(self):
        return self.title

Now the problem is that I'm trying to display this reference in the template. How can I do that? publication.project.title seems not to work. In general publication seems not to have a project field

Template

{% for p in projects %}
    <option value="">{{ p.title }}</option>
    {% if p.projects.id %}
        <option>{{ p.title }}</option>
    {% endif %}
{% endfor %}

What am I missing?

Edit

@login_required
def profile(request, initial_page=1):

    # Get query params
    offset = (initial_page-1) * 10
    limit = offset + 10

    # Handle default GET request
    current_user = request.user
    pending_publications = Publication.objects.filter(authors=current_user).order_by('-year')
    number_of_pending_publications = Publication.objects.filter(authors=current_user).count()
    number_of_pending_pages = int(number_of_pending_publications/10) + 1
    confirmed_publications = Publication.objects.filter(authors2=current_user).order_by('-year')
    number_of_confirmed_publications = Publication.objects.filter(authors2=current_user).count()
    number_of_confirmed_pages = int(number_of_confirmed_publications/10) + 1
    projects = Project.objects.all()

    if (number_of_confirmed_publications % 10) == 0:
        number_of_confirmed_pages -=1 
    if (number_of_pending_publications % 10) == 0:
        number_of_pending_pages -=1

    # Set up form defaults
    default_form_values = {
        "first_name" : request.user.first_name, 
        "last_name" : request.user.last_name,
        "email" : request.user.email, 
        "organization" : request.user.organization,
        "bio" : request.user.bio,
    }

    # Set up context variables for html
    context = {
        'form': UpdateProfileForm(initial = default_form_values),
        'projects' : projects,
        'confirmed_publications' : confirmed_publications[offset:limit],
        'number_of_confirmed_publications' : number_of_confirmed_publications,
        'number_of_confirmed_pages' : number_of_confirmed_pages,
        'pending_publications' : pending_publications[offset:limit],
        'number_of_pending_publications' : number_of_pending_publications,
        'number_of_pending_pages' : number_of_pending_pages,
        'initial_pending_page' : initial_page,
        'initial_confirmed_page' : 1,

    }

    # Render page
    return render(request, 'main/publication.html', context)

Upvotes: 1

Views: 3793

Answers (1)

Chris
Chris

Reputation: 2212

You are handling a 1 -> n relationship. In order to access the properties of your Publication instances from a Project instance you either need to call yourmodel_set or provide a related name.

1. Using _set

Supposing you have a Project instance in your view and would like to iterate over all related Publications this would be e.g

for pub in project.publication_set.all():
    print(pub.title)

In a template using the django template language this would be (using your template):

{% for p in projects %}
{{ p.title }}
    {% for pub in p.publication_set.all %}
    {{ pub.title }}
    {% endfor %}
{% endfor %}

2. Using a related name

If you do not like the _set thing you can add a related name and use this to access the related objects.

In your models:

class Publication(models.Model):
    id = models.IntegerField(primary_key=True)
    title = models.CharField(max_length=254)
    authors_string = models.CharField(max_length=254, default='')
    project = models.ForeignKey(Project, on_delete=models.DO_NOTHING, blank=True, null=True, related_name='publications')

    def __str__(self):
        return self.title

and then in your template

{% for p in projects %}
    {{ p.title }}
        {% for pub in p.publications.all %}
        {{ pub.title }}
        {% endfor %}
{% endfor %}

If you want to access a Project from a Publication, the syntax you stated is correct, e.g:

pub.project.title

Upvotes: 4

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