C#•2w ago

✅ Enums as strings on AspNetCore controller .NET 9

I have added this enum

[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Locale
{
    [JsonStringEnumMemberName("ar_AE")]
    ArabicUae,

[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Locale
{
    [JsonStringEnumMemberName("ar_AE")]
    ArabicUae,

In swagger it shows as expected

6 Replies

James.OP•2w ago

However when you send a request it fails because of model validation

    [HttpPost("/authorize", Name = "Authorize")]
    [Consumes("application/x-www-form-urlencoded")]
    [ProducesResponseType<AuthorizeResponse>(StatusCodes.Status200OK)]
    public async Task<IActionResult> Authorize(
        [FromForm] string login,
        [FromForm] string password,
        [FromForm] Locale? locale,
        CancellationToken cancellationToken)

    [HttpPost("/authorize", Name = "Authorize")]
    [Consumes("application/x-www-form-urlencoded")]
    [ProducesResponseType<AuthorizeResponse>(StatusCodes.Status200OK)]
    public async Task<IActionResult> Authorize(
        [FromForm] string login,
        [FromForm] string password,
        [FromForm] Locale? locale,
        CancellationToken cancellationToken)

James.OP•2w ago

Sehra•2w ago

form data does not use encode using json

Sehra•2w ago

you want something like [TypeConverter(typeof(EnumMemberConverter<Locale>))] and [EnumMember(Value = "ae_AE")] see https://stackoverflow.com/a/68625960

Stack Overflow

Can't map [FromForm] enum with [EnumMember] in asp.net core api 3.1

I have an enum with EnumMemberAttribute specified for its values: public enum HireStrategy { [EnumMember(Value = "30-days")] Days30, [EnumMember(Value = "60-days")] ...

Sehra•2w ago

but for localization there is already support in aspnet to grab it from various places https://learn.microsoft.com/en-us/aspnet/core/fundamentals/localization?view=aspnetcore-9.0

Globalization and localization in ASP.NET Core

Learn how ASP.NET Core provides services and middleware for localizing content into different languages and cultures.

James.OP•2w ago

Thanks man, sorted the problem instantly. Added support to the converter to take into account JsonStringEnumMemberNameAttribute, so that this converted and json converter will convert in the same way across my app. Thanks but no thanks, I have a spec I need to follow 🙂 For any potential future readers here's my solution:

[TypeConverter(typeof(StringEnumConverter<Locale>))]
[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Locale
{
    [JsonStringEnumMemberName("ar_AE")]
    ArabicUae,
}

[TypeConverter(typeof(StringEnumConverter<Locale>))]
[JsonConverter(typeof(JsonStringEnumConverter))]
public enum Locale
{
    [JsonStringEnumMemberName("ar_AE")]
    ArabicUae,
}

public class StringEnumConverter<T> : TypeConverter where T : struct, Enum
{
    public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
    {
        return sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
    }

    public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
    {
        if (value is string stringValue)
        {
            var type = typeof(T);
            foreach (var field in type.GetFields())
            {
                var attr = field.GetCustomAttribute<JsonStringEnumMemberNameAttribute>();
                if (attr != null && string.Equals(attr.Name, stringValue, StringComparison.OrdinalIgnoreCase))
                {
                    return (T)Enum.Parse(type, field.Name);
                }
            }

            if (Enum.TryParse<T>(stringValue, true, out var result))
            {
                return result;
            }
        }
        
        throw new ArgumentException($"Cannot convert {value} to {typeof(T).Name}");
    }
}

public class StringEnumConverter<T> : TypeConverter where T : struct, Enum
{
    public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
    {
        return sourceType == typeof(string) || base.CanConvertFrom(context, sourceType);
    }

    public override object ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
    {
        if (value is string stringValue)
        {
            var type = typeof(T);
            foreach (var field in type.GetFields())
            {
                var attr = field.GetCustomAttribute<JsonStringEnumMemberNameAttribute>();
                if (attr != null && string.Equals(attr.Name, stringValue, StringComparison.OrdinalIgnoreCase))
                {
                    return (T)Enum.Parse(type, field.Name);
                }
            }

            if (Enum.TryParse<T>(stringValue, true, out var result))
            {
                return result;
            }
        }
        
        throw new ArgumentException($"Cannot convert {value} to {typeof(T).Name}");
    }
}

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✅ Enums as strings on AspNetCore controller .NET 9

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