Description of problem:

Creating host with interface attached to subnet with IPAM set to internal DB over API fails with "ip can't be blank" when the IP address isn't provided explicitly. API doesn't suggest new IP and model validations fail. UI works without any problem because it makes ajax calls to fetch new IP and pre-fills the form with the retrieved value.

Steps to Reproduce:

Using hammer, create a new host on a subnet with internal DB IPAM, without explicitly setting an IP address.

Actual results:

The API call fails with: "Ip can't be blank"

Expected results:

New host with suggested IP should be created