[
  {
    "key": "firstName",
    "type": "input",
    "templateOptions": {
      "label": "First Name"
    }
  },
  {
    "key": "lastName",
    "type": "input",
    "templateOptions": {
      "label": "Last Name"
    }
  },
  {
    "key": "mac",
    "type": "input",
    "templateOptions": {
      "label": "Mac Address",
      "pattern": "([0-9A-F]{2}[:-]){5}([0-9A-F]{2})"
    }
  },
  {
    "key": "color",
    "type": "radio",
    "templateOptions": {
      "label": "Color Preference (try this out)",
      "options": [
        {
          "label": "No Preference",
          "value": null
        },
        {
          "label": "Green",
          "value": "green"
        },
        {
          "label": "Blue",
          "value": "blue"
        }
      ]
    }
  },
  {
    "key": "reason",
    "type": "textarea",
    "templateOptions": {
      "label": "Why?"
    },
    "expressionProperties": {
      "templateOptions.label": "'Why did you choose ' + model.color + '?'"
    },
    "hideExpression": "!model.color"
  }
]