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

For ASP.NET Core 3 with the Microsoft JSON library (System.Text.Json)

In Startup.cs/ConfigureServices():

services
    .AddControllersWithViews(...) // or AddControllers() in a Web API
    .AddJsonOptions(options => 
        options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));

For ASP.NET Core 3 with the Json.NET (Newtonsoft.Json) library

Install the Swashbuckle.AspNetCore.Newtonsoft package.

In Startup.cs/ConfigureServices():

services
    .AddControllersWithViews(...)
    .AddNewtonsoftJson(options => 
        options.SerializerSettings.Converters.Add(new StringEnumConverter()));
// order is vital, this *must* be called *after* AddNewtonsoftJson()
services.AddSwaggerGenNewtonsoftSupport();

For ASP.NET Core 2

In Startup.cs/ConfigureServices():

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

Pre-ASP.NET Core

httpConfiguration
    .EnableSwagger(c => 
        {
            c.DescribeAllEnumsAsStrings();
        });

Answer 2

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

Answer 3

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 4

ASP.NET Core 3.1

To generate enums as strings using Newtonsoft JSON you must explicitly add Newtonsoft support by adding AddSwaggerGenNewtonsoftSupport() as follows:

services.AddMvc()
    ...
    .AddNewtonsoftJson(opts =>
    {
        opts.SerializerSettings.Converters.Add(new StringEnumConverter());
    });


services.AddSwaggerGen(...);
services.AddSwaggerGenNewtonsoftSupport(); //

This is available via a new package, Swashbuckle.AspNetCore.Newtonsoft. It looks like everything else works fine without this package apart from enum converter support.

Answer 5

.NET CORE 3.1 and SWAGGER 5

if you need a simple solution to selectively make enums passed as strings:

using System.Text.Json.Serialization;


[JsonConverter(typeof(JsonStringEnumConverter))]
public enum MyEnum
{
    A, B
}

Note, we use System.Text.Json.Serialization namespace, not the Newtonsoft.Json!

Answer 6

My variant for enum stings with values:

Configure Services:

services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "web server api", Version = "v1" });
                c.SchemaFilter<EnumSchemaFilter>();
            });

Filter:

public class EnumSchemaFilter : ISchemaFilter
    {
        public void Apply(OpenApiSchema model, SchemaFilterContext context)
        {
            if (context.Type.IsEnum)
            {
                model.Enum.Clear();
                Enum.GetNames(context.Type)
                    .ToList()
                    .ForEach(name => model.Enum.Add(new OpenApiString($"{Convert.ToInt64(Enum.Parse(context.Type, name))} - {name}")));
            }
        }
    }

Answer 7

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 8

if anyone is interested i have modified the code to work with

.NET CORE 3 and Swagger V5

    public class SwaggerAddEnumDescriptions : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        // add enum descriptions to result models
        foreach (var property in swaggerDoc.Components.Schemas.Where(x => x.Value?.Enum?.Count > 0))
        {
            IList<IOpenApiAny> propertyEnums = property.Value.Enum;
            if (propertyEnums != null && propertyEnums.Count > 0)
            {
                property.Value.Description += DescribeEnum(propertyEnums, property.Key);
            }
        }

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

    private void DescribeEnumParameters(IDictionary<OperationType, OpenApiOperation> operations, OpenApiDocument swaggerDoc)
    {
        if (operations != null)
        {
            foreach (var oper in operations)
            {
                foreach (var param in oper.Value.Parameters)
                {
                    var paramEnum = swaggerDoc.Components.Schemas.FirstOrDefault(x => x.Key == param.Name);
                    if (paramEnum.Value != null)
                    {
                        param.Description += DescribeEnum(paramEnum.Value.Enum, paramEnum.Key);
                    }
                }
            }
        }
    }

    private Type GetEnumTypeByName(string enumTypeName)
    {
        return AppDomain.CurrentDomain
            .GetAssemblies()
            .SelectMany(x => x.GetTypes())
            .FirstOrDefault(x => x.Name == enumTypeName);
    }

    private string DescribeEnum(IList<IOpenApiAny> enums, string proprtyTypeName)
    {
        List<string> enumDescriptions = new List<string>();
        var enumType = GetEnumTypeByName(proprtyTypeName);
        if (enumType == null)
            return null;

        foreach (IOpenApiAny enumOption in enums)
        {
            if (enumOption is OpenApiString @string)
            {
                string enumString = @string.Value;

                enumDescriptions.Add(string.Format("{0} = {1}", (int)Enum.Parse(enumType, enumString), enumString));
            }
            else if (enumOption is OpenApiInteger integer)
            {
                int enumInt = integer.Value;

                enumDescriptions.Add(string.Format("{0} = {1}", enumInt, Enum.GetName(enumType, enumInt)));
            }
        }

        return string.Join(", ", enumDescriptions.ToArray());
    }
}

Answer 9

ASP.NET Core 6 / ASP.NET Core 7

In your program.cs:

builder.Services.AddControllers().AddJsonOptions(options =>
{
    options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
});

Please also note:

DescribeAllEnumsAsStrings is obsolete

Answer 10

This is not possible with standard OpenAPI. Enums are described only with their string values.

Fortunately you can do it with some non-standard extensions that are utilized by your client generator.

NSwag supports x-enumNames

AutoRest supports x-ms-enum.

Openapi-generator supports x-enum-varnames

Other generators might support one of these extensions or have their own.

To generate x-enumNames for NSwag create the following schema filter:

public class EnumSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (context.Type.IsEnum)
        {
            var array = new OpenApiArray();
            array.AddRange(Enum.GetNames(context.Type).Select(n => new OpenApiString(n)));
            // NSwag
            schema.Extensions.Add("x-enumNames", array);
            // Openapi-generator
            schema.Extensions.Add("x-enum-varnames", array);
        }
    }
}

And register it as:

services.AddSwaggerGen(options =>
{
    options.SchemaFilter<EnumSchemaFilter>();
});

Answer 11

With asp.net core 3

using System.Text.Json.Serialization;

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
         services.AddControllers().AddJsonOptions(options =>
             options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));

But it seems that Swashbuckle Version 5.0.0-rc4 is not ready to support that. So we need to use an option(deprecated) in the Swashbuckle config file until it supports and reflects it like Newtonsoft library.

public void ConfigureServices(IServiceCollection services)
{ 
      services.AddSwaggerGen(c =>
      {
            c.DescribeAllEnumsAsStrings();

The difference between this answer and other answers is using only the Microsoft JSON library instead of Newtonsoft.

Answer 12

I have found nice workaround Here:

@PauloVetor - solved it using ShemaFilter like this:

public class EnumSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema model, SchemaFilterContext context)
    {
        if (context.Type.IsEnum)
        {
            model.Enum.Clear();
            Enum.GetNames(context.Type)
                .ToList()
                .ForEach(n =>
                {
                    model.Enum.Add(new OpenApiString(n)); 
                    model.Type = "string";
                    model.Format = null;
                });
        }
    }
}

And in Startup.cs:

services.AddSwaggerGen(options =>
{
    options.SchemaFilter<EnumSchemaFilter>();
}

Note: use this solution when enums are generated as ints into json (StringEnumConverter is not used or cannot be used). Swagger will show enum names, and will pass the string value into the API, and luckily ASP.NET Core can handle enum values as ints and also as strings, where the string value has to be case-insentitive enum name (e.g. for enum Priority.Low, ASP.NET Core accepts string values Low, low, lOw, etc).

Answer 13

I have modified Hosam Rehani's answer to work with nullable enums and with collection of enums also. The previous answer also works only if a property is named exactly like it's type. All these problems are addressed in the code below.

It works with .net core 3.x and swagger 5.x.

it could be more efficient by not searching for the enum type twice in some cases.

class SwaggerAddEnumDescriptions : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        // add enum descriptions to result models
        foreach (var property in swaggerDoc.Components.Schemas.Where(x => x.Value?.Enum?.Count > 0))
        {
            IList<IOpenApiAny> propertyEnums = property.Value.Enum;
            if (propertyEnums != null && propertyEnums.Count > 0)
            {
                property.Value.Description += DescribeEnum(propertyEnums, property.Key);
            }
        }

        // add enum descriptions to input parameters
        foreach (var pathItem in swaggerDoc.Paths)
        {
            DescribeEnumParameters(pathItem.Value.Operations, swaggerDoc, context.ApiDescriptions, pathItem.Key);
        }
    }

    private void DescribeEnumParameters(IDictionary<OperationType, OpenApiOperation> operations, OpenApiDocument swaggerDoc, IEnumerable<ApiDescription> apiDescriptions, string path)
    {
        path = path.Trim('/');
        if (operations != null)
        {
            var pathDescriptions = apiDescriptions.Where(a => a.RelativePath == path);
            foreach (var oper in operations)
            {
                var operationDescription = pathDescriptions.FirstOrDefault(a => a.HttpMethod.Equals(oper.Key.ToString(), StringComparison.InvariantCultureIgnoreCase));
                foreach (var param in oper.Value.Parameters)
                {
                    var parameterDescription = operationDescription.ParameterDescriptions.FirstOrDefault(a => a.Name == param.Name);
                    if (parameterDescription != null && TryGetEnumType(parameterDescription.Type, out Type enumType))
                    {
                        var paramEnum = swaggerDoc.Components.Schemas.FirstOrDefault(x => x.Key == enumType.Name);
                        if (paramEnum.Value != null)
                        {
                            param.Description += DescribeEnum(paramEnum.Value.Enum, paramEnum.Key);
                        }
                    }
                }
            }
        }
    }

    bool TryGetEnumType(Type type, out Type enumType)
    {
        if (type.IsEnum)
        {
            enumType = type;
            return true;
        }
        else if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
        {
            var underlyingType = Nullable.GetUnderlyingType(type);
            if (underlyingType != null && underlyingType.IsEnum == true)
            {
                enumType = underlyingType;
                return true;
            }
        }
        else
        {
            Type underlyingType = GetTypeIEnumerableType(type);
            if (underlyingType != null && underlyingType.IsEnum)
            {
                enumType = underlyingType;
                return true;
            }
            else
            {
                var interfaces = type.GetInterfaces();
                foreach (var interfaceType in interfaces)
                {
                    underlyingType = GetTypeIEnumerableType(interfaceType);
                    if (underlyingType != null && underlyingType.IsEnum)
                    {
                        enumType = underlyingType;
                        return true;
                    }
                }
            }
        }

        enumType = null;
        return false;
    }

    Type GetTypeIEnumerableType(Type type)
    {
        if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(IEnumerable<>))
        {
            var underlyingType = type.GetGenericArguments()[0];
            if (underlyingType.IsEnum)
            {
                return underlyingType;
            }
        }

        return null;
    }

    private Type GetEnumTypeByName(string enumTypeName)
    {
        return AppDomain.CurrentDomain
            .GetAssemblies()
            .SelectMany(x => x.GetTypes())
            .FirstOrDefault(x => x.Name == enumTypeName);
    }

    private string DescribeEnum(IList<IOpenApiAny> enums, string proprtyTypeName)
    {
        List<string> enumDescriptions = new List<string>();
        var enumType = GetEnumTypeByName(proprtyTypeName);
        if (enumType == null)
            return null;

        foreach (OpenApiInteger enumOption in enums)
        {
            int enumInt = enumOption.Value;

            enumDescriptions.Add(string.Format("{0} = {1}", enumInt, Enum.GetName(enumType, enumInt)));
        }

        return string.Join(", ", enumDescriptions.ToArray());
    }
}

to use the filter add c.DocumentFilter<SwaggerAddEnumDescriptions>(); to swagger configuration in Startup.cs.

Answer 14

For .NET core 5 it is same as .NET core 3.1 which is to add

   options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());

Example:

services.AddControllers(options =>
{
    options.ReturnHttpNotAcceptable = true;
    var builder = new AuthorizationPolicyBuilder().RequireAuthenticatedUser();
    options.Filters.Add(new AuthorizeFilter(builder.Build()));
 }).AddJsonOptions(options =>
 {
    options.JsonSerializerOptions.IgnoreNullValues = true;
    options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter());
 });

Answer 15

Simple Solution. It works for me.

   using System.Text.Json.Serialization;
    
    
    [JsonConverter(typeof(JsonStringEnumConverter))]
    public enum Priority
    {
        Low, 
        Medium,
        High
    }

Answer 16

To display the enums as strings in swagger, please configure the JsonStringEnumConverter by adding the following line in ConfigureServices :

services.AddControllers().AddJsonOptions(options =>
            options.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));

If you want to display the enums as strings and int values, you could try to create an EnumSchemaFilter to change the schema, as below:

public class EnumSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema model, SchemaFilterContext context)
    {
        if (context.Type.IsEnum)
        {
            model.Enum.Clear();
            Enum.GetNames(context.Type)
                .ToList()
                .ForEach(name => model.Enum.Add(new OpenApiString($"{Convert.ToInt64(Enum.Parse(context.Type, name))} = {name}")));
        }
    }
}

Configure the SwaggerGen to use the above SchemaFilter :

services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new OpenApiInfo
            {
                Version = "v1",
                Title = "ToDo API",
                Description = "A simple example ASP.NET Core Web API",
                TermsOfService = new Uri("https://example.com/terms"),
                Contact = new OpenApiContact
                {
                    Name = "Shayne Boyer",
                    Email = string.Empty,
                    Url = new Uri("https://twitter.com/spboyer"),
                },
                License = new OpenApiLicense
                {
                    Name = "Use under LICX",
                    Url = new Uri("https://example.com/license"),
                }
            });
              
            c.SchemaFilter<EnumSchemaFilter>();
        });

Answer 17

in .net core 3.1 & swagger 5.0.0 :

using System.Linq;
using Microsoft.OpenApi.Any;
using Microsoft.OpenApi.Models;
using Swashbuckle.AspNetCore.SwaggerGen;

namespace WebFramework.Swagger
{
    public class EnumSchemaFilter : ISchemaFilter
    {
        public void Apply(OpenApiSchema schema, SchemaFilterContext context)
        {
            if (context.Type.IsEnum)
            {
                var enumValues = schema.Enum.ToArray();
                var i = 0;
                schema.Enum.Clear();
                foreach (var n in Enum.GetNames(context.Type).ToList())
                {
                    schema.Enum.Add(new OpenApiString(n + $" = {((OpenApiPrimitive<int>)enumValues[i]).Value}"));
                    i++;
                }
            }
        }
    }

}

and in Startup.cs :

services.AddSwaggerGen(options =>
            {
                #region  EnumDesc
                options.SchemaFilter<EnumSchemaFilter>();
                #endregion
            });

Answer 18

If you are using newtonsof.json then use this

using Newtonsoft.Json.Converters;


[JsonConverter(typeof(StringEnumConverter))]
public enum MyEnum
{
    A, B
}

If you are using System.Text.Json.Serialization

using System.Text.Json.Serialization;


[JsonConverter(typeof(JsonStringEnumConverter))]
public enum MyEnum
{
    A, B
}

Answer 19

After searching for answers here, I found the partial solution for the issue with displaying enums in the Schema as [SomeEnumString = 0, AnotherEnumString = 1], but all of the answers related to this are only partially correct as @OhWelp mentioned in one of the comments.

Here's the full solution for .NET core (2, 3, currently working on 6):

    public class EnumSchemaFilter : ISchemaFilter
    {
        public void Apply(OpenApiSchema model, SchemaFilterContext context)
        {
            if (context.Type.IsEnum)
            {
                model.Enum.Clear();

                var names = Enum.GetNames(context.Type).ToList();

                names.ForEach(name => model.Enum.Add(new OpenApiString($"{GetEnumIntegerValue(name, context)} = {name}")));


                 // the missing piece that will make sure that the new schema will not replace the mock value with a wrong value 
                // this is the default behavior - the first possible enum value as a default "example" value
                model.Example = new OpenApiInteger(GetEnumIntegerValue(names.First(), context));
            }
        }

        private int GetEnumIntegerValue(string name, SchemaFilterContext context) => Convert.ToInt32(Enum.Parse(context.Type, name));
    }

And in the startup/program:

    services.AddSwaggerGen(options =>
        {
            options.SchemaFilter<EnumSchemaFilter>();
        });

EDIT: Refactored the code a bit, if you want to see the original version which is more similar to the rest of the answers please, check the chronology of edits.

Answer 20

Go to Program.cs and put the below code:

using Microsoft.AspNetCore.Http.Json;
using MvcJsonOptions = Microsoft.AspNetCore.Mvc.JsonOptions;

.....

builder.Services.Configure<JsonOptions>(o => o.SerializerOptions.Converters.Add(new JsonStringEnumConverter()));
builder.Services.Configure<MvcJsonOptions>(o => o.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));

Answer 21

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 22

I got it working for .NET 6 Web API using the following code based from the other answers here:

1 - Create a DocumentFilter

/// <summary>
/// Add enum value descriptions to Swagger
/// </summary>
public class SwaggerEnumDocumentFilter : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        // add enum descriptions to result models
        foreach (var property in swaggerDoc.Components.Schemas)
        {
            var propertyEnums = property.Value.Enum;
            if (propertyEnums is { Count: > 0 })
            {
                property.Value.Description += DescribeEnum(propertyEnums, property.Key);
            }
        }

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

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

            var affectedOperations = new List<OperationType> { OperationType.Get, OperationType.Post, OperationType.Put, OperationType.Patch };

            foreach (var operation in pathItem.Operations)
            {
                if (affectedOperations.Contains(operation.Key))
                {
                    DescribeEnumParameters(operation.Value.Parameters);
                }
            }
        }
    }

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

        foreach (var param in parameters)
        {
            if (param.Schema.Reference != null)
            {
                var enumType = GetEnumTypeByName(param.Schema.Reference.Id);
                var names = Enum.GetNames(enumType).ToList();

                param.Description += string.Join(", ", names.Select(name => $"{Convert.ToInt32(Enum.Parse(enumType, name))} - {name}").ToList());
            }
        }
    }

    private static Type GetEnumTypeByName(string enumTypeName)
    {
        if (string.IsNullOrEmpty(enumTypeName))
        {
            return null;
        }

        try
        {
            return AppDomain.CurrentDomain
                            .GetAssemblies()
                            .SelectMany(x => x.GetTypes())
                            .Single(x => x.FullName != null
                                      && x.Name == enumTypeName);
        }
        catch (InvalidOperationException e)
        {
            throw new Exception($"SwaggerDoc: Can not find a unique Enum for specified typeName '{enumTypeName}'. Please provide a more unique enum name.");
        }
    }

    private static string DescribeEnum(IEnumerable<IOpenApiAny> enums, string propertyTypeName)
    {
        var enumType = GetEnumTypeByName(propertyTypeName);

        if (enumType == null)
        {
            return null;
        }

        var parsedEnums = new List<OpenApiInteger>();
        foreach (var @enum in enums)
        {
            if (@enum is OpenApiInteger enumInt)
            {
                parsedEnums.Add(enumInt);
            }
        }

        return string.Join(", ", parsedEnums.Select(x => $"{x.Value} - {Enum.GetName(enumType, x.Value)}"));
    }

}

2 - Add it to your Program.cs file

   services.AddSwaggerGen(config =>
        {

            config.DocumentFilter<SwaggerEnumDocumentFilter>();

        })

Answer 23

write code inside Startup.cs

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

Answer 24

There were a number of shortcomings I found in the other answers for what we were looking for, so I thought I'd supply my own take on this. We're using ASP.NET Core 3.1 with System.Text.Json, but our approach works irrespective of the JSON serializer used.

Our goal was to accept lower-camel-cased enum string values in both the ASP.NET Core API as well as document the same in Swagger. We're currently making use of [DataContract] and [EnumMember], so the approach is to take the lower-camel-cased value from the EnumMember value property and use that across the board.

Our sample enum:

[DataContract]
public class enum Colors
{
  [EnumMember(Value="brightPink")]
  BrightPink,
  [EnumMember(Value="blue")]
  Blue
}

We'll use the EnumMember values in Swashbuckle by using an ISchemaFilter as in the following:

public class DescribeEnumMemberValues : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (context.Type.IsEnum)
        {
            schema.Enum.Clear();

            //Retrieve each of the values decorated with an EnumMember attribute
            foreach (var member in context.Type.GetMembers())
            {
                var memberAttr = member.GetCustomAttributes(typeof(EnumMemberAttribute), false).FirstOrDefault();
                if (memberAttr != null)
                {
                    var attr = (EnumMemberAttribute) memberAttr;
                    schema.Enum.Add(new OpenApiString(attr.Value));
                }
            }
        }
    }
}

We're using a third-party NuGet package (GitHub repo) to ensure that this naming scheme is also utilized in ASP.NET Core. Configure it in Startup.cs within ConfigureServices with:

services.AddControllers()
  .AddJsonOptions(opt => opt.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverterWithAttributeSupport()));

Finally, we need to register our ISchemaFilter in Swashbuckle, so also add the following also in ConfigureServices():

services.AddSwaggerGen(c => {
  c.SchemaFilter<DescribeEnumMemberValues>();
});

Answer 25

If the version of the swagger were 5.5.x, then you need to:

1. install: Install-Package Swashbuckle.AspNetCore.Newtonsoft -Version 5.5.0

2. services.AddSwaggerGenNewtonsoftSupport();

Reference: https://github.com/domaindrivendev/Swashbuckle.AspNetCore#systemtextjson-stj-vs-newtonsoft

Answer 26

.Net Core 3.0

   using Newtonsoft.Json.Converters;

 services
    .AddMvc(options =>
    {
     options.EnableEndpointRouting = false;
     })
    .AddNewtonsoftJson(options => options.SerializerSettings.Converters.Add(new StringEnumConverter()))

Answer 27

ASP NET SOLUTION

In my api docs one enum was still shown as int despite the property being marked with StringEnumConverter. We couldn't afford using the global setting for all enums mentioned above. Adding this line in SwaggerConfig solved the issue:

c.MapType<ContactInfoType>(() => new Schema { type = "string", @enum = Enum.GetNames(typeof(ContactInfoType))});

Answer 28

In order to generate enums with name and value you can use this solution.

Prerequisites:

• you're using NSwag or Openapi-generator to generate API client
• you have an old Web Api project (pre .NET Core) and use Swashbuckle.WebApi package

Register SchemaFilter:

GlobalConfiguration.Configuration
    .EnableSwagger("/swagger", c =>
    {
        c.SchemaFilter<EnumSchemaFilter>();
    });

EnumSchemaFilter:

public class EnumSchemaFilter : ISchemaFilter
{
    public void Apply(Schema schema, SchemaRegistry schemaRegistry, Type type)
    {
        var enumProperties = schema.properties?.Where(p => p.Value.@enum != null);
        if(enumProperties != null)
        {
            foreach (var property in enumProperties)
            {
                var array = Enum.GetNames(type.GetProperty(property.Key).PropertyType).ToArray();
                property.Value.vendorExtensions.Add("x-enumNames", array); // NSwag
                property.Value.vendorExtensions.Add("x-enum-varnames", array); // Openapi-generator
            }
        }
    }
}

Answer 29

I had some problems to get the answers for Swagger and .NET for version 6.x working. I wanted to continue using integer values for enums, but also display a list of possible values (in a readable format). So here is my modified version (includes parts of some answers), maybe it saves some time for some of you ;)

P.S. There is still some room for improvement, you should also check if the logic of the method "GetEnumTypeByName" fits for you. In my case I wanted to primarily update descriptions only for project internal and unique enums.

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.OpenApi.Any;
using Microsoft.OpenApi.Models;
using Models.Api;
using Swashbuckle.AspNetCore.SwaggerGen;

/// <summary>
/// Add enum value descriptions to Swagger
/// </summary>
public class SwaggerEnumDocumentFilter : IDocumentFilter
{
    public void Apply(OpenApiDocument swaggerDoc, DocumentFilterContext context)
    {
        // add enum descriptions to result models
        foreach (var property in swaggerDoc.Components.Schemas)
        {
            var propertyEnums = property.Value.Enum;
            if (propertyEnums is { Count: > 0 })
            {
                property.Value.Description += DescribeEnum(propertyEnums, property.Key);
            }
        }

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

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

            var affectedOperations = new List<OperationType> { OperationType.Get, OperationType.Post, OperationType.Put };

            foreach (var operation in pathItem.Operations)
            {
                if (affectedOperations.Contains(operation.Key))
                {
                    DescribeEnumParameters(operation.Value.Parameters);
                }
            }
        }
    }

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

        foreach (var param in parameters)
        {
            if (param.Schema.Reference != null)
            {
                param.Description += DescribeEnum(param.Schema.Reference.Id);
            }
        }
    }

    private static Type GetEnumTypeByName(string enumTypeName)
    {
        if (string.IsNullOrEmpty(enumTypeName))
        {
            return null;
        }

        try
        {
            var projectNamespaceRoot = "MyProject.";

            return AppDomain.CurrentDomain
                            .GetAssemblies()
                            .SelectMany(x => x.GetTypes())
                            .Single(x => x.FullName != null
                                      && x.FullName.StartsWith(projectNamespaceRoot)
                                      && x.Name == enumTypeName);
        }
        catch (InvalidOperationException _)
        {
            throw new ApiException($"SwaggerDoc: Can not find a unique Enum for specified typeName '{enumTypeName}'. Please provide a more unique enum name.");
        }
    }

    private static string DescribeEnum(IEnumerable<IOpenApiAny> enums, string propertyTypeName)
    {
        var enumType = GetEnumTypeByName(propertyTypeName);

        if (enumType == null)
        {
            return null;
        }

        var parsedEnums = new List<OpenApiInteger>();
        foreach (var @enum in enums)
        {
            if (@enum is OpenApiInteger enumInt)
            {
                parsedEnums.Add(enumInt);
            }
        }

        return string.Join(", ", parsedEnums.Select(x => $"{x} = {Enum.GetName(enumType, x.Value)}"));
    }
}

As already mentioned by others, you have to register this Filter inside your Swagger setup:

services.AddSwaggerGen(options =>
        {
            options.SwaggerDoc("v1", new OpenApiInfo
            {
                // some configuration
            });
              
            options.DocumentFilter<SwaggerEnumDocumentFilter>();
        });

Answer 30

There is a nuget that handles all the tweaks suggested here. It particularly useful if you do not want to change how enums are serialized (because text might be more brittle than a integer value) but just need more documentation in the Swagger description.

The nuget also works with .NET 7 minimal APIs:

using Unchase.Swashbuckle.AspNetCore.Extensions.Extensions;
...
builder.Services.ConfigureSwaggerGen(options =>
{
    options.AddEnumsWithValuesFixFilters();
});

Answer 31

In .Net 6 with NSwag and System.Text.Json for me works:

services.AddControllersWithViews()
       .AddJsonOptions(o => o.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter())) 

and

services.AddOpenApiDocument(configure =>
{
       ...
       configure.GenerateEnumMappingDescription = true;
});

It accepts int-s and strings, generates enums in open-api and .ts client with names and show enums with names in SwaggerUI

export enum PaymentDirection {
    Input = "Input",
    Output = "Output",
}