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using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Localization;
using System;
using System.ComponentModel.DataAnnotations;
using Timeline.Helpers;
namespace Timeline.Models.Validation
{
/// <summary>
/// Generate a message from a localizer factory.
/// If localizerFactory is null, it should return a culture-invariant message.
/// </summary>
/// <param name="localizerFactory">The localizer factory. Could be null.</param>
/// <returns>The message.</returns>
public delegate string ValidationMessageGenerator(IStringLocalizerFactory? localizerFactory);
/// <summary>
/// A validator to validate value.
/// </summary>
public interface IValidator
{
/// <summary>
/// Validate given value.
/// </summary>
/// <param name="value">The value to validate.</param>
/// <returns>Validation success or not and the message generator.</returns>
(bool, ValidationMessageGenerator) Validate(object? value);
}
/// <summary>
/// Convenient base class for validator.
/// </summary>
/// <typeparam name="T">The type of accepted value.</typeparam>
/// <remarks>
/// Subclass should override <see cref="DoValidate(T, out string)"/> to do the real validation.
/// This class will check the nullity and type of value. If value is null or not of type <typeparamref name="T"/>
/// it will return false and not call <see cref="DoValidate(T, out string)"/>.
///
/// If you want some other behaviours, write the validator from scratch.
/// </remarks>
public abstract class Validator<T> : IValidator
{
public (bool, ValidationMessageGenerator) Validate(object? value)
{
if (value == null)
{
return (false, factory =>
factory?.Create("Models.Validation.Validator")?["ValidatorMessageNull"]
?? Resources.Models.Validation.Validator.InvariantValidatorMessageNull
);
}
if (value is T v)
{
return DoValidate(v);
}
else
{
return (false, factory =>
factory?.Create("Models.Validation.Validator")?["ValidatorMessageBadType", typeof(T).FullName]
?? Resources.Models.Validation.Validator.InvariantValidatorMessageBadType);
}
}
protected static ValidationMessageGenerator SuccessMessageGenerator { get; } = factory =>
factory?.Create("Models.Validation.Validator")?["ValidatorMessageSuccess"] ?? Resources.Models.Validation.Validator.InvariantValidatorMessageSuccess;
protected abstract (bool, ValidationMessageGenerator) DoValidate(T value);
}
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Field | AttributeTargets.Parameter,
AllowMultiple = false)]
public class ValidateWithAttribute : ValidationAttribute
{
private readonly IValidator _validator;
/// <summary>
/// Create with a given validator.
/// </summary>
/// <param name="validator">The validator used to validate.</param>
public ValidateWithAttribute(IValidator validator)
{
_validator = validator ?? throw new ArgumentNullException(nameof(validator));
}
/// <summary>
/// Create the validator with default constructor.
/// </summary>
/// <param name="validatorType">The type of the validator.</param>
public ValidateWithAttribute(Type validatorType)
{
if (validatorType == null)
throw new ArgumentNullException(nameof(validatorType));
if (!typeof(IValidator).IsAssignableFrom(validatorType))
throw new ArgumentException(
Resources.Models.Validation.Validator.ValidateWithAttributeNotValidator,
nameof(validatorType));
try
{
_validator = (Activator.CreateInstance(validatorType) as IValidator)!;
}
catch (Exception e)
{
throw new ArgumentException(
Resources.Models.Validation.Validator.ValidateWithAttributeCreateFail, e);
}
}
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
var (result, messageGenerator) = _validator.Validate(value);
if (result)
{
return ValidationResult.Success;
}
else
{
var localizerFactory = validationContext.GetRequiredService<IStringLocalizerFactory>();
return new ValidationResult(messageGenerator(localizerFactory));
}
}
}
}
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