.net - 在 .net 中验证数据

Question

我正在寻找任何推荐的验证框架或 N 层客户端应用程序的模式，我想编写一次验证方法并将其绑定(bind)到 WPF GUI，如果可能的话还用于服务器端和客户端相关业务逻辑。

Answer 1

很简单，您的业务实体应该包含一个部分来存储业务验证(即业务逻辑)。无论您是在设计基于 Web 的应用程序、基于客户端的应用程序、移动应用程序等，这都适用。非常灵活。

假设您有一个像客户这样的业务对象(实体):

public class Customer
 {
         public Customer(int customerId, string company, string city, string country)
        {
            CustomerId = customerId;
            Company = company;
            City = city;
            Country = country;
        }
  }

然后你意识到你希望你的业务逻辑声明你验证一个客户ID(此外它> 0)，你需要一个公司名称(没有一个客户是无效的)等等。这些验证是你的业务逻辑层。因此，您可以更改您的客户类以继承自 BusinessObject 层，这样您的类就变成了这样:

    public class Customer : BusinessObject
    {
        /// <summary>
        /// Default constructor for customer class.
        /// Initializes automatic properties.
        /// </summary>
        public Customer()
        {
            // Default property values
            Orders = new List<Order>();

            // Business rules
            AddRule(new ValidateId("CustomerId"));

            AddRule(new ValidateRequired("Company"));
            AddRule(new ValidateLength("Company", 1, 40));

        }

        /// <summary>
        /// Overloaded constructor for the Customer class.
        /// </summary>
        /// <param name="customerId">Unique Identifier for the Customer.</param>
        /// <param name="company">Name of the Customer.</param>
        /// <param name="city">City where Customer is located.</param>
        /// <param name="country">Country where Customer is located.</param>
        public Customer(int customerId, string company, string city, string country)
            : this()
        {
            CustomerId = customerId;
            Company = company;
            City = city;
            Country = country;
        }
//much more code like methods...
}

您不需要 BusinessObject 类型的对象，但 businessobject 用作​​存储验证错误和业务规则的抽象类。业务规则最终是您在调用 AddRule 时声明的规则:

public abstract class BusinessObject
{
    /// <summary>
    /// Default value for version number (used in LINQ's optimistic concurrency)
    /// </summary>
    protected static readonly string _versionDefault = "NotSet";

    // List of business rules
    private IList<BusinessRule> _businessRules = new List<BusinessRule>();

    // List of validation errors (following validation failure)
    private IList<string> _validationErrors = new List<string>();

    /// <summary>
    /// Gets list of validations errors.
    /// </summary>
    public IList<string> ValidationErrors
    {
        get { return _validationErrors; }
    }

    /// <summary>
    /// Adds a business rule to the business object.
    /// </summary>
    /// <param name="rule"></param>
    protected void AddRule(BusinessRule rule)
    {
        _businessRules.Add(rule);
    }

    /// <summary>
    /// Determines whether business rules are valid or not.
    /// Creates a list of validation errors when appropriate.
    /// </summary>
    /// <returns></returns>
    public bool Validate()
    {
        bool isValid = true;

        _validationErrors.Clear();

        foreach (BusinessRule rule in _businessRules)
        {
            if (!rule.Validate(this))
            {
                isValid = false;
                _validationErrors.Add(rule.ErrorMessage);
            }
        }
        return isValid;
    }
}

需要实现validateid、validaterequired、validatelength等业务规则:

public class ValidateId : BusinessRule
{
    public ValidateId(string propertyName)
        : base(propertyName)
    {
        ErrorMessage = propertyName + " is an invalid identifier";
    }

    public ValidateId(string propertyName, string errorMessage)
        : base(propertyName)
    {
        ErrorMessage = errorMessage;
    }

    public override bool Validate(BusinessObject businessObject)
    {
        try
        {
            int id = int.Parse(GetPropertyValue(businessObject).ToString());
            return id >= 0;
        }
        catch
        {
            return false;
        }
    }

     public class ValidateLength : BusinessRule
        {
            private int _min;
            private int _max;

            public ValidateLength(string propertyName, int min, int max)
                : base(propertyName)
            {
                _min = min;
                _max = max;

                ErrorMessage = propertyName + " must be between " + _min + " and " + _max + " characters long.";
            }

            public ValidateLength(string propertyName, string errorMessage, int min, int max)
                : this(propertyName, min, max)
            {
                ErrorMessage = errorMessage;
            }

            public override bool Validate(BusinessObject businessObject)
            {
                int length = GetPropertyValue(businessObject).ToString().Length;
                return length >= _min && length <= _max;
            }
        }

这只是 validatelength 和 validateid 的两个示例，您可以提出 validaterequired(检查该值是否存在)。他们都实现了一个业务规则类:

public abstract class BusinessRule
    {
        public string PropertyName { get; set; }
        public string ErrorMessage { get; set; }

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="propertyName">The property name to which rule applies.</param>
        public BusinessRule(string propertyName)
        {
            PropertyName = propertyName;
            ErrorMessage = propertyName + " is not valid";
        }

        /// <summary>
        /// Overloaded constructor
        /// </summary>
        /// <param name="propertyName">The property name to which rule applies.</param>
        /// <param name="errorMessage">The error message.</param>
        public BusinessRule(string propertyName, string errorMessage)
            : this(propertyName)
        {
            ErrorMessage = errorMessage;
        }

        /// <summary>
        /// Validation method. To be implemented in derived classes.
        /// </summary>
        /// <param name="businessObject"></param>
        /// <returns></returns>
        public abstract bool Validate(BusinessObject businessObject);

        /// <summary>
        /// Gets value for given business object's property using reflection.
        /// </summary>
        /// <param name="businessObject"></param>
        /// <param name="propertyName"></param>
        /// <returns></returns>
        protected object GetPropertyValue(BusinessObject businessObject)
        {
            return businessObject.GetType().GetProperty(PropertyName).GetValue(businessObject, null);
        }
    }

因此您的 businessobject 类只保留所需业务规则的列表和它捕获的验证错误。业务规则类仅存储属性名称和一条错误消息，以防规则未正确应用。它还包含为每个验证类定义的抽象 validate() 方法。每个验证类都不同，因为验证 id 与验证必填字段不同。

gang of four website在这方面有很多很好的帮助。大部分代码取自他们的模型。