使用OR条件的条件RequiredIf条件

Question

我正在上下面的课：

public class CustomerNameSearchRequest
{
    public string FirstName { get; set; }

    [Required]
    public string LastName { get; set; }

    public string StreetAddress { get; set; }

    public string City { get; set; }

    public string State { get; set; }

    public string ZipCode { get; set; }

}

我有以下条件：The LastName property is required IF the FirstName is null OR StreetAddress is null OR City is null OR State is null OR ZipCode is null

我已经查找了堆栈溢出，并且习惯于遵循RequiredIf验证属性。

/// <summary>
/// Provides conditional validation based on related property value.
/// </summary>
[AttributeUsage(AttributeTargets.Property, AllowMultiple = true)]
public sealed class RequiredIfAttribute : ValidationAttribute
{
    #region Properties

    /// <summary>
    /// Gets or sets the other property name that will be used during validation.
    /// </summary>
    /// <value>
    /// The other property name.
    /// </value>
    public string OtherProperty { get; private set; }

    /// <summary>
    /// Gets or sets the display name of the other property.
    /// </summary>
    /// <value>
    /// The display name of the other property.
    /// </value>
    public string OtherPropertyDisplayName { get; set; }

    /// <summary>
    /// Gets or sets the other property value that will be relevant for validation.
    /// </summary>
    /// <value>
    /// The other property value.
    /// </value>
    public object OtherPropertyValue { get; private set; }

    /// <summary>
    /// Gets or sets a value indicating whether other property's value should match or differ from provided other property's value (default is <c>false</c>).
    /// </summary>
    /// <value>
    ///   <c>true</c> if other property's value validation should be inverted; otherwise, <c>false</c>.
    /// </value>
    /// <remarks>
    /// How this works
    /// - true: validated property is required when other property doesn't equal provided value
    /// - false: validated property is required when other property matches provided value
    /// </remarks>
    public bool IsInverted { get; set; }

    /// <summary>
    /// Gets a value that indicates whether the attribute requires validation context.
    /// </summary>
    /// <returns><c>true</c> if the attribute requires validation context; otherwise, <c>false</c>.</returns>
    public override bool RequiresValidationContext
    {
        get { return true; }
    }

    #endregion

    #region Constructor

    /// <summary>
    /// Initializes a new instance of the <see cref="RequiredIfAttribute"/> class.
    /// </summary>
    /// <param name="otherProperty">The other property.</param>
    /// <param name="otherPropertyValue">The other property value.</param>
    public RequiredIfAttribute(string otherProperty, object otherPropertyValue)
        : base("'{0}' is required because '{1}' has a value {3}'{2}'.")
    {
        this.OtherProperty = otherProperty;
        this.OtherPropertyValue = otherPropertyValue;
        this.IsInverted = false;
    }

    #endregion

    /// <summary>
    /// Applies formatting to an error message, based on the data field where the error occurred.
    /// </summary>
    /// <param name="name">The name to include in the formatted message.</param>
    /// <returns>
    /// An instance of the formatted error message.
    /// </returns>
    public override string FormatErrorMessage(string name)
    {
        return string.Format(
            CultureInfo.CurrentCulture,
            base.ErrorMessageString,
            name,
            this.OtherPropertyDisplayName ?? this.OtherProperty,
            this.OtherPropertyValue,
            this.IsInverted ? "other than " : "of ");
    }

    /// <summary>
    /// Validates the specified value with respect to the current validation attribute.
    /// </summary>
    /// <param name="value">The value to validate.</param>
    /// <param name="validationContext">The context information about the validation operation.</param>
    /// <returns>
    /// An instance of the <see cref="T:System.ComponentModel.DataAnnotations.ValidationResult" /> class.
    /// </returns>
    protected override ValidationResult IsValid(object value, ValidationContext validationContext)
    {
        if (validationContext == null)
        {
            throw new ArgumentNullException("validationContext");
        }

        PropertyInfo otherProperty = validationContext.ObjectType.GetProperty(this.OtherProperty);
        if (otherProperty == null)
        {
            return new ValidationResult(
                string.Format(CultureInfo.CurrentCulture, "Could not find a property named '{0}'.", this.OtherProperty));
        }

        object otherValue = otherProperty.GetValue(validationContext.ObjectInstance);

        // check if this value is actually required and validate it
        if (!this.IsInverted && object.Equals(otherValue, this.OtherPropertyValue) ||
            this.IsInverted && !object.Equals(otherValue, this.OtherPropertyValue))
        {
            if (value == null)
            {
                return new ValidationResult(this.FormatErrorMessage(validationContext.DisplayName));
            }

            // additional check for strings so they're not empty
            string val = value as string;
            if (val != null && val.Trim().Length == 0)
            {
                return new ValidationResult(this.FormatErrorMessage(validationContext.DisplayName));
            }
        }

        return ValidationResult.Success;
    }
}

但是，如果我要实现以下多个RequiredIf属性：

[RequiredIf(nameof(FirstName), null)]
[RequiredIf(nameof(StreetAddress), null)]
[RequiredIf(nameof(City), null)]
[RequiredIf(nameof(State), null)]
[RequiredIf(nameof(ZipCode), null)]
public string LastName { get; set; }

不管如何，它都将强制LastName属性具有一个值。如何在RequiredIf属性中实现OR条件?还有更好的代码可以帮助我实现我的需求吗？

提前谢谢。

Answer 1

可以将属性更改为接受具有以下字段和值对的字符串数组：

    public class CustomerNameSearchRequest
    {
        public string FirstName { get; set; }

        [RequiredIf(new string[] {
            "FirstName, !null",
            "StreetAddress, !null",
            "City, !null",
            "State, !null",
            "ZipCode, !null"
        })]
        public string LastName { get; set; }

        public string StreetAddress { get; set; }

        public string City { get; set; }

        public string State { get; set; }

        public string ZipCode { get; set; }
    }

并以下列方式创建RequiredIf属性：

    public class RequiredIfAttribute : ValidationAttribute
    {
        private const string DefaultErrorMessageFormatString = "The {0} field is required.";
        private readonly string[] _dependentProperties;

        public RequiredIfAttribute(string[] dependentProperties)
        {
            _dependentProperties = dependentProperties;
            ErrorMessage = DefaultErrorMessageFormatString;
        }

        private bool IsValueRequired(string checkValue, object currentValue)
        {
            if (checkValue.Equals("!null", StringComparison.InvariantCultureIgnoreCase))
            {
                return currentValue != null;
            }

            return checkValue.Equals(currentValue);
        }

        protected override ValidationResult IsValid(object value, ValidationContext context)
        {
            object instance = context.ObjectInstance;
            Type type = instance.GetType();
            bool valueRequired = false;

            foreach (string s in _dependentProperties)
            {
                var fieldValue = s.Split(',').ToList().Select(k => k.Trim()).ToArray();

                object propertyValue = type.GetProperty(fieldValue[0]).GetValue(instance, null);

                valueRequired = IsValueRequired(fieldValue[1], propertyValue);
            }

            if (valueRequired)
            {
                return value != null
                    ? ValidationResult.Success
                    : new ValidationResult(context.DisplayName + " required. ");
            }
            return ValidationResult.Success;
        }
    }

2.验证字段是否需要(不)的IsValueRequired方法

    private bool IsValueRequired(string checkValue, object currentValue)
    {
        if (checkValue.Equals("!null", StringComparison.InvariantCultureIgnoreCase))
        {
            return currentValue != null;
        }

        return checkValue.Equals(currentValue);
    }

3. IsValid检查字段为空还是不为空：

    protected override ValidationResult IsValid(object value, ValidationContext context)
    {
        object instance = context.ObjectInstance;
        Type type = instance.GetType();
        bool valueRequired = false;

        foreach (string s in _dependentProperties)
        {
            var fieldValue = s.Split(',').ToList().Select(k => k.Trim()).ToArray();

            object propertyValue = type.GetProperty(fieldValue[0]).GetValue(instance, null);

            valueRequired = IsValueRequired(fieldValue[1], propertyValue);
        }

        if (valueRequired)
        {
            return value != null
                ? ValidationResult.Success
                : new ValidationResult(context.DisplayName + " required. ");
        }
        return ValidationResult.Success;
    }

来源：

1. https://www.codeproject.com/Questions/5161571/How-to-use-data-annotation-to-check-for-two-values;