Articolo
11/18/2011

StringLengthAttribute Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Specifies the maximum and minimum number of characters that are allowed for an entity member.

Inheritance Hierarchy

System.Object
  System.Attribute
    System.ComponentModel.DataAnnotations.ValidationAttribute
      System.ComponentModel.DataAnnotations.StringLengthAttribute

Namespace: System.ComponentModel.DataAnnotations
Assembly: System.ComponentModel.DataAnnotations (in System.ComponentModel.DataAnnotations.dll)

Syntax

'Declaration
<AttributeUsageAttribute(AttributeTargets.Property Or AttributeTargets.Field Or AttributeTargets.Parameter, AllowMultiple := False)> _
Public Class StringLengthAttribute _
    Inherits ValidationAttribute

[AttributeUsageAttribute(AttributeTargets.Property|AttributeTargets.Field|AttributeTargets.Parameter, AllowMultiple = false)]
public class StringLengthAttribute : ValidationAttribute

The StringLengthAttribute type exposes the following members.

Constructors

	Name	Description
	StringLengthAttribute	Initializes a new instance of the StringLengthAttribute class.

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Properties

	Name	Description
	ErrorMessage	Gets or sets the non-localizable error message to display when validation fails. (Inherited from ValidationAttribute.)
	ErrorMessageResourceName	Gets or sets the property name on the resource type that provides the localizable error message. (Inherited from ValidationAttribute.)
	ErrorMessageResourceType	Gets or sets the resource type that provides the localizable error message. (Inherited from ValidationAttribute.)
	ErrorMessageString	Gets the localized or non-localized error message. (Inherited from ValidationAttribute.)
	MaximumLength	Gets the maximum length of a string.
	MinimumLength	Gets or sets the minimum length of a string.

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Methods

	Name	Description
	Equals	Infrastructure. Returns a value that indicates whether this instance is equal to a specified object. (Inherited from Attribute.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	FormatErrorMessage	Applies formatting to an error message that is displayed when the string value is not within the specified length. (Overrides ValidationAttribute.FormatErrorMessage(String).)
	GetHashCode	Returns the hash code for this instance. (Inherited from Attribute.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValidationResult	Determines whether the specified object is valid and returns an object that includes the results of the validation check. (Inherited from ValidationAttribute.)
	IsValid	Determines whether the specified object is valid. (Inherited from ValidationAttribute.)
	Match	When overridden in a derived class, returns a value that indicates whether this instance equals a specified object. (Inherited from Attribute.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Validate	Determines whether the specified object is valid and throws a ValidationException if the object is not valid. (Inherited from ValidationAttribute.)

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Remarks

You apply the StringLengthAttribute attribute to a property when you need to specify the number of characters allowed for the property. If the value of the property is nulla null reference (Nothing in Visual Basic), the value will not fail validation for the StringLengthAttribute attribute. To validate that the value is not nulla null reference (Nothing in Visual Basic), use the RequiredAttribute attribute.

Examples

The following example shows how to specify the number of characters for a property named LastName.

Public Class Customer
  <Required()> _
  <StringLength(50)> _
  Public Property LastName As String
    'Implement Get and Set logic
  End Property
End Class

public class Customer
{
  [Required]
  [StringLength(50)]
  public string LastName { get; set; }
}

Version Information

Silverlight

Supported in: 5, 4, 3

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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