title: Join Multiple Querysets From Different Base Models Django
body: <p>I currently have two different models.</p>
  
  <pre><code>class Journal(models.Model):
      date = models.DateField()
      from_account = models.ForeignKey(Account,related_name='transferred_from')
      to_account = models.ForeignKey(Account,related_name='transferred_to')
      amount = models.DecimalField(max_digits=8, decimal_places=2)
      memo = models.CharField(max_length=100,null=True,blank=True)
  
  class Ledger(models.Model):
      date = models.DateField()
      bank_account = models.ForeignKey(EquityAccount,related_name='paid_from')
      account = models.ForeignKey(Account)
      amount = models.DecimalField(max_digits=8, decimal_places=2)
      name = models.ForeignKey(Party)
      memo = models.CharField(max_length=100,null=True,blank=True)
  </code></pre>
  
  <p>I am creating a report in a view and get the following error:
  Merging 'ValuesQuerySet' classes must involve the same values in each case.</p>
  
  <p>What I'm trying to do is only pull out the fields that are common so I can concatenate both of them e.g. </p>
  
  <pre><code>def report(request):
  
      ledger = GeneralLedger.objects.values('account').annotate(total=Sum('amount'))
      journal = Journal.objects.values('from_account').annotate(total=Sum('amount'))
      report = ledger &amp; journal
  ...
  </code></pre>
  
  <p>If I try to make them exactly the same to test e.g.</p>
  
  <pre><code>def report(request):
  
      ledger = GeneralLedger.objects.values('memo').annotate(total=Sum('amount'))
      journal = Journal.objects.values('memo').annotate(total=Sum('amount'))
      report = ledger &amp; journal
  ...
  </code></pre>
  
  <p>I get this error:
  Cannot combine queries on two different base models.</p>
  
  <p>Anyone know how this can be accomplished?</p>