StringLengthAttribute 類別

定義

指定資料欄位中允許的最小和最大字元長度。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)]
public class StringLengthAttribute : System.ComponentModel.DataAnnotations.ValidationAttribute
[System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false)]
public class StringLengthAttribute : System.ComponentModel.DataAnnotations.ValidationAttribute
[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Parameter | System.AttributeTargets.Property, AllowMultiple=false)>]
type StringLengthAttribute = class
    inherit ValidationAttribute
[<System.AttributeUsage(System.AttributeTargets.Field | System.AttributeTargets.Property, AllowMultiple=false)>]
type StringLengthAttribute = class
    inherit ValidationAttribute
Public Class StringLengthAttribute
Inherits ValidationAttribute
繼承
StringLengthAttribute
屬性

範例

下列範例顯示如何限制欄位中的字元數。The following example shows how to limit the number of characters in a field. 此範例適用于 AdventureWorksLT 資料庫之 Products 資料表中的 ThumbnailPhotoFileName 欄位。This example works with the ThumbnailPhotoFileName field in the Products table in the AdventureWorksLT database. 欄位的限制為4個字元,方法是將 StringLengthAttribute 屬性套用至代表 Product 實體的部分類別。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  

備註

ASP.NET 動態資料可讓 CRUD (在資料模型中建立、讀取、更新和刪除) 作業。ASP.NET Dynamic Data enables CRUD (Create, Read, Update and Delete) operations in a data model. 您可以指定插入或更新資料時,每個欄位的最小和最大字元長度。You can specify the minimum and maximum length of characters for each field when data is being inserted or updated. 若為字元資料類型, MinimumLengthMaximumLength 屬性會識別儲存字串所需的最大位元組數目。For character data types, the MinimumLength and MaximumLength properties identify the largest number of bytes that are required in order to store a string.

您可以在錯誤訊息中使用 複合格式 預留位置: {0} 是屬性的名稱; {1} 是最大長度,而 {2} 是最小長度。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. 預留位置會對應至在執行時間傳遞給方法的引數 String.FormatThe placeholders correspond to arguments that are passed to the String.Format method at runtime.

建構函式

StringLengthAttribute(Int32)

使用指定的最大長度,初始化 StringLengthAttribute 類別的新執行個體。Initializes a new instance of the StringLengthAttribute class by using a specified maximum length.

屬性

ErrorMessage

取得或設定錯誤訊息,此錯誤訊息會在驗證失敗時與驗證控制項產生關聯。Gets or sets an error message to associate with a validation control if validation fails.

(繼承來源 ValidationAttribute)
ErrorMessageResourceName

取得或設定要在驗證失敗時用來查閱 ErrorMessageResourceType 屬性值的錯誤訊息資源名稱。Gets or sets the error message resource name to use in order to look up the ErrorMessageResourceType property value if validation fails.

(繼承來源 ValidationAttribute)
ErrorMessageResourceType

取得或設定資源類型,此類型可在驗證失敗時用於查閱錯誤訊息。Gets or sets the resource type to use for error-message lookup if validation fails.

(繼承來源 ValidationAttribute)
ErrorMessageString

取得當地語系化的驗證錯誤訊息。Gets the localized validation error message.

(繼承來源 ValidationAttribute)
MaximumLength

取得或設定字串的最大長度。Gets or sets the maximum length of a string.

MinimumLength

取得或設定字串的長度下限。Gets or sets the minimum length of a string.

RequiresValidationContext

取得值,這個值表示屬性是否需要驗證內容。Gets a value that indicates whether the attribute requires validation context.

(繼承來源 ValidationAttribute)
TypeId

在衍生類別中實作時,取得這個 Attribute 的唯一識別碼。When implemented in a derived class, gets a unique identifier for this Attribute.

(繼承來源 Attribute)

方法

Equals(Object)

傳回值,這個值指出此執行個體是否與指定的物件相等。Returns a value that indicates whether this instance is equal to a specified object.

(繼承來源 Attribute)
FormatErrorMessage(String)

將格式套用到指定的錯誤訊息 Applies formatting to a specified error message.

GetHashCode()

傳回這個執行個體的雜湊碼。Returns the hash code for this instance.

(繼承來源 Attribute)
GetType()

取得目前執行個體的 TypeGets the Type of the current instance.

(繼承來源 Object)
GetValidationResult(Object, ValidationContext)

檢查指定的值在目前的驗證屬性方面是否有效。Checks whether the specified value is valid with respect to the current validation attribute.

(繼承來源 ValidationAttribute)
IsDefaultAttribute()

在衍生類別中覆寫時,表示這個執行個體的值是衍生類別的預設值。When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class.

(繼承來源 Attribute)
IsValid(Object)

判斷指定的物件是否有效 Determines whether a specified object is valid.

IsValid(Object, ValidationContext)

根據目前的驗證屬性,驗證指定的值。Validates the specified value with respect to the current validation attribute.

(繼承來源 ValidationAttribute)
Match(Object)

在衍生類別中覆寫時,會傳回值,表示這個執行個體是否等於指定物件。When overridden in a derived class, returns a value that indicates whether this instance equals a specified object.

(繼承來源 Attribute)
MemberwiseClone()

建立目前 Object 的淺層複製。Creates a shallow copy of the current Object.

(繼承來源 Object)
ToString()

傳回代表目前物件的字串。Returns a string that represents the current object.

(繼承來源 Object)
Validate(Object, String)

驗證指定的物件。Validates the specified object.

(繼承來源 ValidationAttribute)
Validate(Object, ValidationContext)

驗證指定的物件。Validates the specified object.

(繼承來源 ValidationAttribute)

明確介面實作

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

將一組名稱對應至一組對應的分派識別項 (Dispatch Identifier)。Maps a set of names to a corresponding set of dispatch identifiers.

(繼承來源 Attribute)
_Attribute.GetTypeInfo(UInt32, UInt32, IntPtr)

擷取物件的類型資訊,可以用來取得介面的類型資訊。Retrieves the type information for an object, which can be used to get the type information for an interface.

(繼承來源 Attribute)
_Attribute.GetTypeInfoCount(UInt32)

擷取物件提供的類型資訊介面數目 (0 或 1)。Retrieves the number of type information interfaces that an object provides (either 0 or 1).

(繼承來源 Attribute)
_Attribute.Invoke(UInt32, Guid, UInt32, Int16, IntPtr, IntPtr, IntPtr, IntPtr)

提供物件所公開的屬性和方法的存取權。Provides access to properties and methods exposed by an object.

(繼承來源 Attribute)

適用於