DateTimeModelBinder.cs

public class DateTimeModelBinder : IModelBinder
{
    public static readonly Type[] SupportedTypes = [typeof(DateTime), typeof(DateTime?)];

    public async Task BindModelAsync(ModelBindingContext bindingContext)
    {
        if (bindingContext == null)
        {
            throw new ArgumentNullException(nameof(bindingContext));
        }

        if (!SupportedTypes.Contains(bindingContext.ModelType))
        {
            return;
        }

        var modelName = GetModelName(bindingContext);

        var valueProviderResult = bindingContext.ValueProvider.GetValue(modelName);
        if (valueProviderResult == ValueProviderResult.None)
        {
            return;
        }

        bindingContext.ModelState.SetModelValue(modelName, valueProviderResult);

        var dateToParse = valueProviderResult.FirstValue;
        if (string.IsNullOrEmpty(dateToParse))
        {
            return;
        }

        var dateTime = ParseDate(bindingContext, dateToParse);

        bindingContext.Result = ModelBindingResult.Success(dateTime);

        await Task.CompletedTask;
    }
    
    private DateTime? ParseDate(ModelBindingContext bindingContext, string dateToParse)
        {
            var attribute = GetDateTimeModelBinderAttribute(bindingContext);
            var dateFormat = attribute?.DateFormat;

            if (string.IsNullOrEmpty(dateFormat))
            {
                return Helper.ParseDateTime(dateToParse);
            }

            return Helper.ParseDateTime(dateToParse, new string[] { dateFormat });
        }

        private DateTimeModelBinderAttribute GetDateTimeModelBinderAttribute(ModelBindingContext bindingContext)
        {
            var modelName = GetModelName(bindingContext);

            var paramDescriptor = bindingContext.ActionContext.ActionDescriptor.Parameters
                .Where(x => x.ParameterType == typeof(DateTime?))
                .Where((x) =>
                {
                    // See comment in GetModelName() on why we do this.
                    var paramModelName = x.BindingInfo?.BinderModelName ?? x.Name;
                    return paramModelName.Equals(modelName);
                })
                .FirstOrDefault();

            if (!(paramDescriptor is ControllerParameterDescriptor ctrlParamDescriptor))
            {
                return null;
            }

            var attribute = ctrlParamDescriptor.ParameterInfo
                .GetCustomAttributes(typeof(DateTimeModelBinderAttribute), false)
                .FirstOrDefault();

            return (DateTimeModelBinderAttribute)attribute;
        }

        private string GetModelName(ModelBindingContext bindingContext)
        {
            if (!string.IsNullOrEmpty(bindingContext.BinderModelName))
            {
                return bindingContext.BinderModelName;
            }

            return bindingContext.ModelName;
        }
}

public class DateTimeModelBinderAttribute : ModelBinderAttribute
{
    public string DateFormat { get; set; }

    public DateTimeModelBinderAttribute()
        : base(typeof(DateTimeModelBinder))
    {
    }
}