Swagger UI Web Api documentation Present enums as strings?

Enable globally

From the docs:

httpConfiguration
    .EnableSwagger(c => 
        {
            c.SingleApiVersion("v1", "A title for your API");
            
            c.DescribeAllEnumsAsStrings(); // this will do the trick
        });

Enum/string conversion on particular property

Also, if you want this behavior only on a particular type and property, use the StringEnumConverter:

public class Letter 
{
    [Required]
    public string Content {get; set;}

    [Required]
    [EnumDataType(typeof(Priority))]
    [JsonConverter(typeof(StringEnumConverter))]
    public Priority Priority {get; set;}
}

If you’re using Newtonsoft and Swashbuckle v5.0.0 or higher

You’ll also need this package:

Swashbuckle.AspNetCore.Newtonsoft

And this in your startup:

services.AddSwaggerGenNewtonsoftSupport(); // explicit opt-in - needs to be placed after AddSwaggerGen()

There’s docs here: https://github.com/domaindrivendev/Swashbuckle.AspNetCore#systemtextjson-stj-vs-newtonsoft