CODEWITHSUNDEEP
django
zoidberg
zoidberg

Reputation: 2199

Django: using objects.values() and get ForeignKey data in template

I have a Django app where my main Model has ForeignKey fields to other DB tables.

class Bugs(models.Model):
    bug_id = models.PositiveIntegerField(primary_key=True)
    bug_severity = models.ForeignKey(Bug_severity,null=True)
    priority = models.ForeignKey(Priority,null=True)
    bug_status = models.ForeignKey(Bug_Status,null=True)
    resolution = models.ForeignKey(Resolution,null=True)
    etc...

All of the ForeignKey tables have a unicode function that returns the name that I want displayed in the template.

class Priority(models.Model):
    value = models.CharField(max_length=64)
    sortkey = models.PositiveSmallIntegerField()
    isactive = models.NullBooleanField()
    visibility_value_id = models.SmallIntegerField(null=True,blank=True)

    def __unicode__(self):
        return self.value

In the view, I am running the query as:

    bugs = Bugs.objects.filter(active=True).order_by('priority__sortkey','bug_severity__sortke

In the template, I can iterate through them, and display the ForeignKey value correctly.

{% for bug in bugs %}
   <tr class="bugrow" >
   <td>{{bug.bug_id}}</td>
   <td>{{bug.priority}}</td>
   <td>{{bug.bug_severity}}</td>
   <td>{{bug.bug_status}}</td>
   <td>{{bug.resolution}}</td>

The problem I am having is that I need to manipulate the Bugs data before sending it to the template, so I use the values() method to return a dictionary. When I pass that dictionary to the template it does not show any fields that point to a ForeignKey.

I'm pretty sure that the reason is that the values only returns the actual database value, so it cannot follow the FK.

The question is, how can I manipulate the data sending it to the template, and still follow the ForeignKey?

Upvotes: 32

Views: 36895

Answers (1)

Michael B
Michael B

Reputation: 5388

I use this method all of the time. You are correct. It only returns the values, so you have to use the "__" notation to get the value from the ForeignKey. For example:

# Get all of the bugs
bugs = Bugs.objects.filter(
    active=True,
).order_by(
    'priority__sortkey',
    'bug_severity__sortkey',
).values(
    'bug_id',
    'priority', # Only the pk (id) of the bug priority FK
    'priority__value', # Equal to bug.priority.value
    'bug_severity',
    'bug_severity__some_value', # Equal to bug.priority.some_value
)

Now, in your template, you do:

{% for bug in bugs %}
    <tr class="bugrow">
        <td>{{ bug.bug_id }}</td>
        <td>{{ bug.priority }}</td>
        <td>{{ bug.priority__value }}</td>
        <td>{{ bug.bug_severity }}</td>
        <td>{{ bug.bug_severity__some_value }}</td>
    </tr>
{% endfor %}

This is covered in the QuerySet.values() documentation, near the bottom:

You can also refer to fields on related models with reverse relations through OneToOneField, ForeignKey and ManyToManyField attributes:

Blog.objects.values('name', 'entry__headline')
[{'name': 'My blog', 'entry__headline': 'An entry'},
 {'name': 'My blog', 'entry__headline': 'Another entry'}, ...]

Upvotes: 64

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