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

Question

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?

Answer 1

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'}, ...]