Begin to introduce a DCL alike view for VMs

uncloud/uncloud_vm/models.py

@@ -127,6 +127,12 @@ class VMDiskImageProduct(models.Model):
         max_length=32, choices=STATUS_CHOICES, default=STATUS_DEFAULT
     )
 
+    def __str__(self):
+        return "VMDiskImage {} ({}): {} gb".format(self.uuid,
+                                                   self.name,
+                                                   self.size_in_gb)
+
+
 
 class VMDiskProduct(models.Model):
     """