Swagger UI Web Api documentation Present enums as strings?

Question

Is there a way to display all enums as their string value in swagger instead of their int value?

I want to be able to submit POST actions and put enums according to their string value without having to look at the enum every time.

I tried DescribeAllEnumsAsStrings but the server then receives strings instead of the enum value which is not what we're looking for.

Has anyone solved this?

Edit:

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

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


public class LettersController : ApiController
{
    [HttpPost]
    public IHttpActionResult SendLetter(Letter letter)
    {
        // Validation not passing when using DescribeEnumsAsStrings
        if (!ModelState.IsValid)
            return BadRequest("Not valid")

        ..
    }

    // In the documentation for this request I want to see the string values of the enum before submitting: Low, Medium, High. Instead of 0, 1, 2
    [HttpGet]
    public IHttpActionResult GetByPriority (Priority priority)
    {

    }
}


public enum Priority
{
    Low, 
    Medium,
    High
}

Answer 1

From the docs:

httpConfiguration
    .EnableSwagger(c => 
        {
            c.SingleApiVersion("v1", "A title for your API");

            c.DescribeAllEnumsAsStrings(); // this will do the trick
        });

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;}
}

Answer 2

So I think I have a similar problem. I'm looking for swagger to generate enums along with the int -> string mapping. The API must accept the int. The swagger-ui matters less, what I really want is code generation with a "real" enum on the other side (android apps using retrofit in this case).

So from my research this ultimately seems to be a limit of the OpenAPI specification which Swagger uses. It's not possible to specify names and numbers for enums.

The best issue I've found to follow is https://github.com/OAI/OpenAPI-Specification/issues/681 which looks like a "maybe soon" but then Swagger would have to be updated, and in my case Swashbuckle as well.

For now my workaround has been to implement a document filter that looks for enums and populates the relevant description with the contents of the enum.

        GlobalConfiguration.Configuration
            .EnableSwagger(c =>
                {
                    c.DocumentFilter<SwaggerAddEnumDescriptions>();

                    //disable this
                    //c.DescribeAllEnumsAsStrings()

SwaggerAddEnumDescriptions.cs:

using System;
using System.Web.Http.Description;
using Swashbuckle.Swagger;
using System.Collections.Generic;

public class SwaggerAddEnumDescriptions : IDocumentFilter
{
    public void Apply(SwaggerDocument swaggerDoc, SchemaRegistry schemaRegistry, IApiExplorer apiExplorer)
    {
        // add enum descriptions to result models
        foreach (KeyValuePair<string, Schema> schemaDictionaryItem in swaggerDoc.definitions)
        {
            Schema schema = schemaDictionaryItem.Value;
            foreach (KeyValuePair<string, Schema> propertyDictionaryItem in schema.properties)
            {
                Schema property = propertyDictionaryItem.Value;
                IList<object> propertyEnums = property.@enum;
                if (propertyEnums != null && propertyEnums.Count > 0)
                {
                    property.description += DescribeEnum(propertyEnums);
                }
            }
        }

        // add enum descriptions to input parameters
        if (swaggerDoc.paths.Count > 0)
        {
            foreach (PathItem pathItem in swaggerDoc.paths.Values)
            {
                DescribeEnumParameters(pathItem.parameters);

                // head, patch, options, delete left out
                List<Operation> possibleParameterisedOperations = new List<Operation> { pathItem.get, pathItem.post, pathItem.put };
                possibleParameterisedOperations.FindAll(x => x != null).ForEach(x => DescribeEnumParameters(x.parameters));
            }
        }
    }

    private void DescribeEnumParameters(IList<Parameter> parameters)
    {
        if (parameters != null)
        {
            foreach (Parameter param in parameters)
            {
                IList<object> paramEnums = param.@enum;
                if (paramEnums != null && paramEnums.Count > 0)
                {
                    param.description += DescribeEnum(paramEnums);
                }
            }
        }
    }

    private string DescribeEnum(IList<object> enums)
    {
        List<string> enumDescriptions = new List<string>();
        foreach (object enumOption in enums)
        {
            enumDescriptions.Add(string.Format("{0} = {1}", (int)enumOption, Enum.GetName(enumOption.GetType(), enumOption)));
        }
        return string.Join(", ", enumDescriptions.ToArray());
    }

}

This results in something like the following on your swagger-ui so at least you can "see what you're doing":

Answer 3

I wanted to use rory_za's answer in a .NET Core application, but I had to modify it a bit to make it work. Here is the implementation I came up with for .NET Core.

I also changed it so it doesn't assume the underlying type is int, and use new lines between the values for easier reading.

/// <summary>
/// Add enum value descriptions to Swagger
/// </summary>
public class EnumDocumentFilter : IDocumentFilter {
    /// <inheritdoc />
    public void Apply(SwaggerDocument swaggerDoc, DocumentFilterContext context) {
        // add enum descriptions to result models
        foreach (var schemaDictionaryItem in swaggerDoc.Definitions) {
            var schema = schemaDictionaryItem.Value;
            foreach (var propertyDictionaryItem in schema.Properties) {
                var property = propertyDictionaryItem.Value;
                var propertyEnums = property.Enum;
                if (propertyEnums != null && propertyEnums.Count > 0) {
                    property.Description += DescribeEnum(propertyEnums);
                }
            }
        }

        if (swaggerDoc.Paths.Count <= 0) return;

        // add enum descriptions to input parameters
        foreach (var pathItem in swaggerDoc.Paths.Values) {
            DescribeEnumParameters(pathItem.Parameters);

            // head, patch, options, delete left out
            var possibleParameterisedOperations = new List<Operation> {pathItem.Get, pathItem.Post, pathItem.Put};
            possibleParameterisedOperations.FindAll(x => x != null)
                .ForEach(x => DescribeEnumParameters(x.Parameters));
        }
    }

    private static void DescribeEnumParameters(IList<IParameter> parameters) {
        if (parameters == null) return;

        foreach (var param in parameters) {
            if (param is NonBodyParameter nbParam && nbParam.Enum?.Any() == true) {
                param.Description += DescribeEnum(nbParam.Enum);
            } else if (param.Extensions.ContainsKey("enum") && param.Extensions["enum"] is IList<object> paramEnums &&
                paramEnums.Count > 0) {
                param.Description += DescribeEnum(paramEnums);
            }
        }
    }

    private static string DescribeEnum(IEnumerable<object> enums) {
        var enumDescriptions = new List<string>();
        Type type = null;
        foreach (var enumOption in enums) {
            if (type == null) type = enumOption.GetType();
            enumDescriptions.Add($"{Convert.ChangeType(enumOption, type.GetEnumUnderlyingType())} = {Enum.GetName(type, enumOption)}");
        }

        return $"{Environment.NewLine}{string.Join(Environment.NewLine, enumDescriptions)}";
    }
}

Then add this to your ConfigureServices method in Startup.cs:

c.DocumentFilter<EnumDocumentFilter>();

Answer 4

I just did this and it works fine!

Startup.cs

services.AddSwaggerGen(c => {
  c.DescribeAllEnumsAsStrings();
});

Model.cs

public enum ColumnType {
  DATE = 0
}

swagger.json

type: {
  enum: ["DATE"],
  type: "string"
}

I hope this helps you how it helped me!

Answer 5

write code inside Startup.cs

services.AddSwaggerGen(c => {
      c.DescribeAllEnumsAsStrings();
    });

Answer 6

DescribeAllEnumsAsStrings() didn't work for me because then as OP said the server receives strings and is expecting ints. To enable server to expect strings I believe you need to add the StringEnumConverter to the SerializerSettings, plus then you can leave off DescribeAllEnumsAsStrings() entirely. In other words in ConfigureServices() in Startup.cs just do this:

services
    .AddMvc(...)
    .AddJsonOptions(options => options.SerializerSettings.Converters.Add(new StringEnumConverter()));