discourse-custom-wizard/spec/fixtures/custom_field/custom_fields.json

{
  "custom_fields": [
    {
      "klass": "topic",
      "name": "topic_field_1",
      "type": "boolean",
      "serializers": [
        "topic_list_item",
        "topic_view"
      ]
    },
    {
      "klass": "post",
      "name": "post_field_1",
      "type": "integer",
      "serializers": [
        "post"
      ]
    }
  ]
}