StringLengthAttribute 類別

定義

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

Object

Attribute

ValidationAttribute

StringLengthAttribute

屬性

AttributeUsageAttribute

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， MinimumLength 和 MaximumLength 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.Format 。The placeholders correspond to arguments that are passed to the String.Format method at runtime.

建構函式

屬性

方法

明確介面實作

適用於