GraphQL single-object endpoints broken

[jdrew82]

Environment

• Python version: 3.7
• Nautobot version: 1.2.0-beta1

Steps to Reproduce

1. Build Nautobot instance of 1.2.0-beta1.
2. Add some sample devices and associated data.
3. Attempt to use the GraphiQL endpoint with a simple query such as:

query ($device_id: ID!) {
  device(id: $device_id) {
    hostname: name
  }
}

along with one of your device's UUID as the query.

Expected Behavior

Expect to see the device's hostname returned.

Observed Behavior

Get error with following:

{
  "errors": [
    {
      "message": "'Device' object has no attribute 'only'",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "device"
      ]
    }
  ],
  "data": {
    "device": null
  }
}

A larger query returns this:

{
  "errors": [
    {
      "message": "'Device' object has no attribute 'select_related'",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "device"
      ]
    }
  ],
  "data": {
    "device": null
  }
}

This appears to be related to optimizations that were done in the core.

[glennmatthews]

Probably a regression introduced by #769.

[glennmatthews]

Seems to be specifically an issue with "single" queries (e.g. device as opposed to devices.) The corresponding devices query seems to work fine:

query ($device_id: String!) {
  devices (id: [$device_id]) {
    hostname: name
  }
}