Fluent Validation with Swagger in Asp.net Core

Question

I am currently using Fluent Validation instead of Data Annotations for my Web api and using swagger for API documentation. Fluent validation rules

Answer 1

After searching i have finally figured out that i needed to IValidationFactory for validator instance.

public class AddFluentValidationRules : ISchemaFilter
{
    private readonly IValidatorFactory _factory;

    /// 

    ///     Default constructor with DI
    /// 
    /// 
    public AddFluentValidationRules(IValidatorFactory factory)
    {
        _factory = factory;
    }

    /// 

    /// 
    /// 
    /// 
    public void Apply(Schema model, SchemaFilterContext context)
    {

        // use IoC or FluentValidatorFactory to get AbstractValidator instance
        var validator = _factory.GetValidator(context.SystemType);
        if (validator == null) return;
        if (model.Required == null)
            model.Required = new List();

        var validatorDescriptor = validator.CreateDescriptor();
        foreach (var key in model.Properties.Keys)
        {
            foreach (var propertyValidator in validatorDescriptor
                .GetValidatorsForMember(ToPascalCase(key)))
            {
                if (propertyValidator is NotNullValidator 
                  || propertyValidator is NotEmptyValidator)
                    model.Required.Add(key);

                if (propertyValidator is LengthValidator lengthValidator)
                {
                    if (lengthValidator.Max > 0)
                        model.Properties[key].MaxLength = lengthValidator.Max;

                    model.Properties[key].MinLength = lengthValidator.Min;
                }

                if (propertyValidator is RegularExpressionValidator expressionValidator)
                    model.Properties[key].Pattern = expressionValidator.Expression;

                // Add more validation properties here;
            }
        }
    }

    /// 

    ///     To convert case as swagger may be using lower camel case
    /// 
    /// 
    /// 
    private static string ToPascalCase(string inputString)
    {
        // If there are 0 or 1 characters, just return the string.
        if (inputString == null) return null;
        if (inputString.Length < 2) return inputString.ToUpper();
        return inputString.Substring(0, 1).ToUpper() + inputString.Substring(1);
    }
}

and add this class to swaggerGen options

options.SchemaFilter();