nswag c# code gen: how to generate enum properties as string

I have a service that exposes a swagger.json file that goes like this:

 ...
      "AccountSummary": {
        "type": "object",
        "additionalProperties": false,
        "properties": {
          "serviceStatus": {
            "description": "The user service status. See the enumerated type for all the details.",
            "oneOf": [
              {
                "$ref": "#/components/schemas/ServiceStatus"
              }
            ]
          },
          "accountingStatus": {
            "description": "The user account status. See the enumerated type for all the details.",
            "oneOf": [
              {
                "$ref": "#/components/schemas/AccountStatus"
              }
            ]
          }
        }
      },
...
      "AccountStatus": {
        "type": "string",
        "description": "",
        "x-enumNames": [
          "Good",
          "PoorStanding",
          "Collection"
        ],
        "enum": [
          "Good",
          "PoorStanding",
          "Collection"
        ]
      },

When I use nswag to generate a client to contact this API, it generates code like this for the DTO:

[System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "10.3.4.0 (Newtonsoft.Json v12.0.0.0)")]
public partial class AccountSummary 
{
	/// <summary>The user service status. See the enumerated type for all the details.</summary>
	[Newtonsoft.Json.JsonProperty("serviceStatus", Required = Newtonsoft.Json.Required.DisallowNull, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
	[Newtonsoft.Json.JsonConverter(typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
	public ServiceStatus ServiceStatus { get; set; }

	/// <summary>The user account status. See the enumerated type for all the details.</summary>
	[Newtonsoft.Json.JsonProperty("accountingStatus", Required = Newtonsoft.Json.Required.DisallowNull, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
	[Newtonsoft.Json.JsonConverter(typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
	public AccountStatus AccountingStatus { get; set; }
}

So, as you can see, the DTO uses an enum for ServiceStatus and AccountingStatus.

We’ve been using nswag like this for a few years and been mostly satisified. But one problem that we found is that when the service adds a new value for the enum, it has the potential of breaking all the clients. For example, if the service adds a value Deleted the the AccountStatus enum, all the cliens will start to break with an error that says something like Deleted is not a recognized value for AccountStatus.

To fix this issue, we would want to tell nswag to generate a simple string (and not an enum) when it sees an enum in a swagger.json spec. Could you please tell me how to do it? I looked in the nswag documentation but I couldn’t find how to do it.

[jkone27]

This would still be useful as an option, many time wrong enum description in server side can cause problems to client, wheras working with simple strings would fix it. for most clients this would be acceptable, as changes in enum values dont need change in contract when type is just a string. We are also facing similar issues e.g. with apis generated in java or openapi contracts specified manually…

[RicoSuter]

Currently there is no such option, you have to postprocess the file before generating the clients - this is quite simple with NJS’s schema visitor class, just remove all “enum” properties…

Something I’d like to add anyway is some sort of “resilient” enum converter, e.g. if the value does not exist then the serializer falls back to eg “Unknown” - this way you lose information but at least deserialization does not fail.

Another option is to use string-based/custom enums instead of “real” enums.