StringLengthAttribute StringLengthAttribute StringLengthAttribute StringLengthAttribute Class

定义

指定数据字段中允许的最小和最大字符长度。Specifies the minimum and maximum length of characters that are allowed in a data field.

public ref class StringLengthAttribute : System::ComponentModel::DataAnnotations::ValidationAttribute
[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property, AllowMultiple=false)]
[System.AttributeUsage(System.AttributeTargets.Property | System.AttributeTargets.Field, AllowMultiple=false)]
[System.AttributeUsage(System.AttributeTargets.Property | System.AttributeTargets.Field | System.AttributeTargets.Parameter, AllowMultiple=false)]
public class StringLengthAttribute : System.ComponentModel.DataAnnotations.ValidationAttribute
type StringLengthAttribute = class
    inherit ValidationAttribute
Public Class StringLengthAttribute
Inherits ValidationAttribute
继承
属性

示例

下面的示例显示了如何限制字段中的字符数。The following example shows how to limit the number of characters in a field. 此示例适用于 AdventureWorksLT 数据库中的产品表中的 ThumbnailPhotoFileName 字段。This example works with the ThumbnailPhotoFileName field in the Products table in the AdventureWorksLT database. 该字段是通过应用限制的 4 个字符StringLengthAttribute属性表示产品实体的分部类。The field is limited 4 characters by applying the StringLengthAttribute attribute to the partial class that represents the Product entity.

[MetadataType(typeof(ProductMetadata))]  
public partial class Product  
{  

}  

public class ProductMetadata  
{  

    [ScaffoldColumn(true)]  
    [StringLength(4, ErrorMessage = "The ThumbnailPhotoFileName value cannot exceed 4 characters. ")]  
    public object ThumbnailPhotoFileName;  

    [ScaffoldColumn(true)]  
    [StringLength(4, ErrorMessage = "The {0} value cannot exceed {1} characters. ")]  
    public object PhotoFileName;  

}  
<MetadataType(GetType(ProductMetadata))> _   
Public Partial Class Product   

End Class   

Public Class ProductMetadata   

    <ScaffoldColumn(True)> _   
    <StringLength(4, ErrorMessage := "The ThumbnailPhotoFileName value cannot exceed 4 characters. ")> _   
    Public ThumbnailPhotoFileName As Object   

    <ScaffoldColumn(True)> _   
    <StringLength(4, ErrorMessage := "The {0} value cannot exceed {1} characters. ")> _   
    Public PhotoFileName As Object   

End Class  

注解

ASP.NET 动态数据启用数据模型中的 CRUD (创建、 读取、 更新和删除) 操作。ASP.NET Dynamic Data enables CRUD (Create, Read, Update and Delete) operations in a data model. 可以指定每个字段的字符的最小值和最大长度时禁止数据插入或更新。You can specify the minimum and maximum length of characters for each field when data is being inserted or updated. 对于字符数据类型MinimumLengthMaximumLength属性确定,这样才能存储字符串所需的字节的最大数目。For character data types, the MinimumLength and MaximumLength properties identify the largest number of bytes that are required in order to store a string.

可以使用复合格式设置错误消息中的占位符:{0}属性; 的名称{1}的最大长度; 和{2}的最小长度。You can use composite formatting placeholders in the error message: {0} is the name of the property; {1} is the maximum length; and {2} is the minimum length. 占位符对应于参数传递给String.Format方法在运行时。The placeholders correspond to arguments that are passed to the String.Format method at runtime.

构造函数

StringLengthAttribute(Int32) StringLengthAttribute(Int32) StringLengthAttribute(Int32) StringLengthAttribute(Int32)

使用指定的最大长度初始化 StringLengthAttribute 类的新实例。Initializes a new instance of the StringLengthAttribute class by using a specified maximum length.

属性

ErrorMessage ErrorMessage ErrorMessage ErrorMessage

获取或设置一条在验证失败的情况下与验证控件关联的错误消息。Gets or sets an error message to associate with a validation control if validation fails.

(Inherited from ValidationAttribute)
ErrorMessageResourceName ErrorMessageResourceName ErrorMessageResourceName ErrorMessageResourceName

获取或设置错误消息资源的名称,在验证失败的情况下,要使用该名称来查找 ErrorMessageResourceType 属性值。Gets or sets the error message resource name to use in order to look up the ErrorMessageResourceType property value if validation fails.

(Inherited from ValidationAttribute)
ErrorMessageResourceType ErrorMessageResourceType ErrorMessageResourceType ErrorMessageResourceType

获取或设置在验证失败的情况下用于查找错误消息的资源类型。Gets or sets the resource type to use for error-message lookup if validation fails.

(Inherited from ValidationAttribute)
ErrorMessageString ErrorMessageString ErrorMessageString ErrorMessageString

获取本地化的验证错误消息。Gets the localized validation error message.

(Inherited from ValidationAttribute)
MaximumLength MaximumLength MaximumLength MaximumLength

获取或设置字符串的最大长度。Gets or sets the maximum length of a string.

MinimumLength MinimumLength MinimumLength MinimumLength

获取或设置字符串的最小长度。Gets or sets the minimum length of a string.

RequiresValidationContext RequiresValidationContext RequiresValidationContext RequiresValidationContext

获取指示特性是否要求验证上下文的值。Gets a value that indicates whether the attribute requires validation context.

(Inherited from ValidationAttribute)
TypeId TypeId TypeId TypeId

在派生类中实现时,获取此 Attribute 的唯一标识符。When implemented in a derived class, gets a unique identifier for this Attribute.

(Inherited from Attribute)

方法

Equals(Object) Equals(Object) Equals(Object) Equals(Object)

返回一个值,该值指示此实例是否与指定的对象相等。Returns a value that indicates whether this instance is equal to a specified object.

(Inherited from Attribute)
FormatErrorMessage(String) FormatErrorMessage(String) FormatErrorMessage(String) FormatErrorMessage(String)

对指定的错误消息应用格式设置。Applies formatting to a specified error message.

GetHashCode() GetHashCode() GetHashCode() GetHashCode()

返回此实例的哈希代码。Returns the hash code for this instance.

(Inherited from Attribute)
GetType() GetType() GetType() GetType()

获取当前实例的 TypeGets the Type of the current instance.

(Inherited from Object)
GetValidationResult(Object, ValidationContext) GetValidationResult(Object, ValidationContext) GetValidationResult(Object, ValidationContext) GetValidationResult(Object, ValidationContext)

检查指定的值对于当前的验证特性是否有效。Checks whether the specified value is valid with respect to the current validation attribute.

(Inherited from ValidationAttribute)
IsDefaultAttribute() IsDefaultAttribute() IsDefaultAttribute() IsDefaultAttribute()

在派生类中重写时,指示此实例的值是否是派生类的默认值。When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.

(Inherited from Attribute)
IsValid(Object) IsValid(Object) IsValid(Object) IsValid(Object)

确定指定的对象是否有效。Determines whether a specified object is valid.

IsValid(Object, ValidationContext) IsValid(Object, ValidationContext) IsValid(Object, ValidationContext) IsValid(Object, ValidationContext)

根据当前的验证特性来验证指定的值。Validates the specified value with respect to the current validation attribute.

(Inherited from ValidationAttribute)
Match(Object) Match(Object) Match(Object) Match(Object)

当在派生类中重写时,返回一个指示此实例是否等于指定对象的值。When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(Inherited from Attribute)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

创建当前 Object 的浅表副本。Creates a shallow copy of the current Object.

(Inherited from Object)
ToString() ToString() ToString() ToString()

返回表示当前对象的字符串。Returns a string that represents the current object.

(Inherited from Object)
Validate(Object, String) Validate(Object, String) Validate(Object, String) Validate(Object, String)

验证指定的对象。Validates the specified object.

(Inherited from ValidationAttribute)
Validate(Object, ValidationContext) Validate(Object, ValidationContext) Validate(Object, ValidationContext) Validate(Object, ValidationContext)

验证指定的对象。Validates the specified object.

(Inherited from ValidationAttribute)

显式界面实现

_Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr) _Attribute.GetIDsOfNames(Guid, IntPtr, UInt32, UInt32, IntPtr)

将一组名称映射为对应的一组调度标识符。Maps a set of names to a corresponding set of dispatch identifiers.

(Inherited from Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr) _Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

检索对象的类型信息,然后可以使用该信息获取接口的类型信息。Retrieves the type information for an object, which can be used to get the type information for an interface.

(Inherited from Attribute)
_Attribute.GetTypeInfoCount(UInt32) _Attribute.GetTypeInfoCount(UInt32) _Attribute.GetTypeInfoCount(UInt32) _Attribute.GetTypeInfoCount(UInt32)

检索对象提供的类型信息接口的数量(0 或 1)。Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(Inherited from Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr) _Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

提供对某一对象公开的属性和方法的访问。Provides access to properties and methods exposed by an object.

(Inherited from Attribute)

适用于