如何迭代Django字典中的外键？

Question

I am pretty new to programming and have a question about iterating over foreign keys in my Django view file.

models.py

class Site(models.Model):
    other fields.......
    sensor = models.ForeignKey("Sensor", blank=True, null=True)
    slug = models.SlugField(unique=True)

views.py

def site(request, site_name_slug):

    context_dict = {}

    empty_field = "<font color='LightGray'>No Data</font>"


    try:
        site = Site.objects.values().get(slug=site_name_slug)
        context_dict['site_slug'] = site_name_slug

        for key, value in site.iteritems():
            if value:
                context_dict[key] = value
            else:
                context_dict[key] = empty_field

Is it possible to do add something like this?

for key, value in (site.sensor).iteritems():
    if value:
        context_dict['sensor_%s' % key] = value
    else:
        context_dict['sensor_%s' % key] = value

So that I don't have to use if/else or try/except for every field in the sensor object.

Answer 1

No, ForeignKeys provide one-to-many relationships.

In your model a given Site will only ever have at most one sensor. There is nothing to iterate over, so what you are asking doesn't make sense.

---

There is no need to specifically iterate through all of the sensor s fields to access them in the template, if you pass the page site into the template, for example as current_site you can access the sensor like so:

{{ current_site.sensor }}

To access a sensors field, (for example if a sensor had a field named "value") just append that, like so:

{{ current_site.sensor.value }}