Django：如何向 ListView 添加查找字段？

Question

I have a model (Listing below) that contains information about ship sailings. The ports for the sailings are given by the duple of xxxx_country and xxxx_port.

I list the sailings with a class ListingView based on ListView. I want to pass the port name to the template rather than xxxx_country and xxxx_port, and I can get the name from a Port model. Here's the code:

# from listing/models.py

class Listing(models.Model):
    # Port Codes - see https://www.worldnetlogistics.com/seaport-codes/
    orig_country = models.CharField(max_length=2, blank=True)
    orig_port = models.CharField(max_length=3, blank=True)
    dest_country = models.CharField(max_length=2, blank=True)
    dest_port = models.CharField(max_length=3, blank=True)


# from codes/models.py

class Port(models.Model):
    country_code = models.CharField(max_length=2, blank=True)
    location_code = models.CharField(max_length=3, blank=True)
    name = models.TextField()


# from listing/views.py

class ListingView(ListView):
    model = Listing

    # need code here that looks up the port name by combination of country_code and location_code
    # one Port object will be returned
    orig_port_name = ?
    dest_port_name = ?

    template_name = 'listing/home.html'  # change from default template name
    ordering =['-ship_sailing']  # reordering the list in reverse order
    paginate_by = 16

What code do I need to put into the view so that I can pass the orrig_port_name and dest_port_name to the template?

Best regards...Paul

Answer 1

What you need here is a ForeignKey that refers to Port objects instead of writing the fields like dest_country and dest_post in the model. This results in duplicated data . Duplicated data is an antipattern since it makes data harder to maintain, store, retrieve, and aggregate.

class Listing(models.Model):
    # Port Codes - see https://www.worldnetlogistics.com/seaport-codes/
    orig = models.,
        on_delete=models.PROTECT,
        related_name='listings_as_orig'
    
    dest = models.,
        on_delete=models.PROTECT,
        related_name='listings_as_dest'
    

Then you can thus fetch the

class ListingView(ListView):
    model = Listing
    queryset = Listing.objects.
    template_name = 'listing/home.html'
    paginate_by = 16

In the template you then can for example list it in a table as:

<table>
  {% for object in object_list %}
    <tr>
        <td>{{ object }}</td>
        <td>{{ object }}</td>
        <td>{{ object }}</td>
        <td>{{ object }}</td>
        <td>{{ object }}</td>
        <td>{{ object }}</td>
    </tr>
  {% endfor %}
</table>