Network / Create bond issue

[igorgnip-gmail]

Describe the bug
Inconsistent and incomplete model save on create and edit network bonds.

MAAS version
Maas 2.6.2 to 2.7.1 unchanged (same bug)

LP issue
no

To Reproduce
Steps to reproduce the behavior:

1. Go to 'machine -> network, select two interfaces and create a bond'
2. Click on 'on bond creation screen' choose 802.3ad type of bond and enable MII monitor with default parameters. Hash type Layer3+4. Right hand select vlan, subnet, ip

• if this is bond creation, on save, most of the parameters will be saved but for example MII mon will not (minor bug)

3. With already having the bond created in previous steps, click on edit bond,
   see that MII monitor is not set.

Some fields get updated, some do not. Most of the time, if bond is created from scratch, all except mii mon gets saved correctly.

For bonds that already exist and have set hash of layer2 (Example), attempt to update/change to some other hash type does not save.

Expected behavior
All touched/changed/dirty fields must be updated on save.

Similar to this but not directly tied to bonds only, right hand ip configuration ... if ip mode is set to unassigned, ip address is not reset to null and thus remains in the database poluting and taking address space. Each of the selected options should clean out all other options that do not apply to the selection.

Example - I switch vlan - since vlan changed, subnet Id must be invalidated, ip address type and ip address value needs to be invalidated and written to database so we do not end up with disparate values in database.

Please excise - my first bug report.
I would love to help as time permits - not sure about how feasible that is.