add string representation to ProteinDomainComplex class

ippisite/ippidb/models.py

@@ -126,6 +126,9 @@ class ProteinDomainComplex(models.Model):
     class Meta:
         verbose_name_plural = "complexes"
 
+    def __str__(self):
+        return '{}-{}'.format(self.protein_id, self.domain_id)
+
 class ProteinDomainBoundComplex(ProteinDomainComplex):
     ppp_copy_nb_per_p = models.IntegerField('Number of copies of the protein in the pocket')
     pockets_nb = models.IntegerField('Total number of pockets in the complex')