Question

There is probably a better way of dealing with non existant query sets…!
The problem i have with this code is that it raises an exception if the normal case will be true! That is: if a workspace name with the same name in the db is not existent.

But instead of having an exception i would like to go for a query that does not return DoesNotExist but true or false

My unelegant code:

 try:
            is_workspace_name = Workspace.objects.get(workspace_name=workspace_name,user=self.user.id )
 except:
        return workspace_name
 if is_workspace_name:
            raise forms.ValidationError(u'%s already exists as a workspace name! Please choose a different one!' %workspace_name  ) 

Thanks a lot!

Answer 1

You can use exists() method. Quoting docs:

Returns True if the QuerySet contains any results, and False if not.
This tries to perform the query in the simplest and fastest way
possible, but it does execute nearly the same query as a normal
QuerySet query.

Remarks: the simplest and fastest way. It is cheaper to use exists (than count) because with exists the database stops counting at first occurrence.

if Workspace.objects.filter(workspace_name=workspace_name, 
                            user=self.user.id).exists()
    raise forms.ValidationError(u'%s already exists ...!' % workspace_name)
else:
    return workspace_name