Ability to specify related objects by attribute during CSV import

[jeremystretch]

Environment

• Python version: 3.5.2
• NetBox version: 2.5.12

Proposed Functionality

Currently, specifying a related object when importing a new object as CSV data requires the related object to have a unique name. For example, importing an IP address assigned to an interface might look like this:

address,status,device,interface
192.0.2.1/24,Active,router3,et-0/0/1

The combination of device name and interface name forms a unique identifier for the interface to which the new IP address should be assigned.

This proposal would allow a related object to be specified by an arbitrary set of fields. For example:

address,status,device,interface
192.0.2.1/24,Active,{site.name: "Raleigh", name: "router3"},et-0/0/1

This would allow the user to have multiple devices named "router3" yet specify the one belonging to site "Raleigh."

The specific formatting is up for debate; the above is intended solely as an illustration of the concept. Special consideration must be given to the use of commas, since parsing of the related object field is being done within the context of processing CSV data.

As I write this, I have to admit it feels like we're trying to squeeze too much functionality out of the CSV format: Maybe a JSON-centric approach would be preferable, but we'd need a low-friction solution for converting spreadsheet data into JSON.

Use Case

This FR was prompted by #2669, which would relax the uniqueness constraint on device and virtual machine names. If a device name cannot be assumed unique, a more robust approach to referencing devices must be implemented. We've already taken a step toward this approach with FlexibleModelChoiceField, which allows referencing an unnamed object by numeric ID (e.g. {{123}}).

Database Changes

None

External Dependencies

Probably none. We may end up using some external parsing library, depending on the approach chosen.

[tb-killa]

Doesn´t we could use this as Base for the #822 and #451 ??

[jeremystretch]

@tb-killa #822, yes. #451 is unrelated to CSV import.

[jeremystretch]

I think it makes sense to do something like this:

address,status,device.site,device.name,interface
192.0.2.1/24,Active,Site D,router3,et-0/0/1

I'm just not sure how we'd get there. It likely means throwing out the existing CSV import forms and starting largely from scratch.