Exercise 1: Adding Custom Range Validation Using Validation Attributes
In this exercise, you will learn how to create a custom validation by using MVC3 ValidationAttribute class at server side. For that purpose, you will include a range validation in the Store Manager example to validate that the price of an album belongs to a certain range.
Task 1 – Adding a validation attribute class
In this task, you will add a validation attribute class at server side. Each attribute to be validated should have a new class inherited from ValidationAttribute.
- Open the begin solution MvcMusicStore.sln at Source\Ex01-Server Side Custom Validation\Begin
- Create a new folder Validations at project root, which will include all the custom rules.
- Add a new C#(Visual Basic) class into the Validations folder and rename it to PriceValidationAttribute.[cs|vb].
Open PriceValidationAttribute.[cs|vb] and add a reference to the System.ComponentModel.DataAnnotations namespace:
using System;
FakePre-447fed3c96b44068a083f301518f7a94-264ca49cd2164e8b8c24b3f73ead9905FakePre-3ef2401ef63f49e88eab5cbcb8691947-f66891b855fc46b5bca93b9e71a5b2causing System.ComponentModel.DataAnnotations;
Imports System
FakePre-46839c3b12684abf9c57966baa9daea1-a48a368783584ef283facc9adfbfa0f5FakePre-63c8ac65b5ce41108102e87cedd24a23-b0fb2fe86fde4a8fbe6515ab38577d6fImports System.ComponentModel.DataAnnotations
Inherit the PriceValidationAttribute class from ValidationAttribute. Additionally, you have to add the AttributeUsage attribute specification, which in this case can be set to fields and properties:
using System;
FakePre-b7efea30a2864ccbbeeb82b23eda3068-88f3009356394a8cb1ab67d20ed70cb5FakePre-167a7382f234444bbbda8722f75451a5-78952e94569c4c9aa13bfb5e0385249eFakePre-4ef85c3717a948e282907878a77b0d11-90dd7fadfd0b4b2a9360dc290ec12ab5FakePre-316c196783824c77a4fe7277554cb31d-3de39ba499d841a4bf15710501af85d1[AttributeUsage(AttributeTargets.Field | AttributeTargets.Property, AllowMultiple = false, Inherited = true)]FakePre-9ec335e1c2874010b7b954a100b45170-9e51438833a14cc789573f316fbdf2f9FakePre-fbf38cd2c43b45f7aa8a3fd6b9908152-751d1395786940b8af9498f8b4e5f26eFakePre-c0e35210b00842fab1acec609ac83252-05c477e53d4a483d80d45d1288dd5a07
Imports System
FakePre-26934cd979634823b85aeb900d249431-55bf0dfdae2c499792ece334cfcdd00dFakePre-35347532c4ee4b56949b35295e7bdfff-f5fcc15a10674d67bc0c166a0a93bd21FakePre-4d16b53a0ff742f7a8018192f88089d7-34973d3f2c9249bea171dbb94ddef388FakePre-3d10e2a0eb774d51a9d0700c53dfed6a-8145c158ce5e460aadbf559878d26341<AttributeUsage(AttributeTargets.Field Or AttributeTargets.Property, AllowMultiple := false, Inherited := true)>FakePre-d634e3011c67472aad0ade0acd7e53b1-c63bbcf262494bea87c9e15ed585db8bFakePre-d144ab7099314d4da41aaa4625b28817-ac70b5ed5f1f4793b6e7295e56c43310FakePre-929234ac5dbc4e30ad73231f10a31c2a-692fcf6acc654c91ab002b9659f0d9bb
AttributeUsage determines how custom attribute class’s attributes can be applied.
-C#-
[System.AttributeUsage(System.AttributeTargets.All,
AllowMultiple = false, Inherited = true)]
-Visual Basic-
<System.AttributeUsage(System.AttributeTargets.All,
AllowMultiple = false, Inherited = true)>
AttributeTargets: This parameter specifies all the application elements on which it is
valid to apply an attribute. It is possible to use
System.AttributeTargets.All, or to specify each member (for example, Class, Property, Method or Field).
AllowMultiple: If it is set to true, then the attribute can be applied more than once in the target
Inherit: If it is set to false, then the attribute is not inherited by derived attribute classes.
You could read more about
AttributeUsage in
msdn.
Define the thresholds for the album price range. To do this, add the following code to the generated class:
(Code Snippet – ASP.NET MVC 3 Custom Validation – Ex1 Custom Range Validation Thresholds - CSharp)
using System;
FakePre-31790c1bd1a7499b8066ce5067b37a8e-5fb2c462ba6c4fef86c87df7663dd66dFakePre-799ae750cccf4cb59bb3ec7a11bd42cd-4c302275179f470caa98453621705efeFakePre-451fb078b1f04f92b3c671a230320c34-3aeb4446ca1446d5b0bd78656b181a51FakePre-35eb212fd43641899244824bfbde1b97-bd0f2d7e6ab5429691d6c3fcfdaf7ed2FakePre-2cb4a92d350b4e1e971d072345c0ecd1-e9c70b8194b14b2ca1731775e9759f1fFakePre-98a0842e843d4100ad804dc9e174664c-bcfc8acffacd4c9393bcab81bbba7e95FakePre-281335a8c80e4c5eae2a945cf9fb885f-7234633c5fc342ca878bf21808b3eb60FakePre-25e8f20ad90c48b7a91b4a44d8fca22a-35121107d4e44f07b43196b00b197153FakePre-1aeea78dfeb5401bbee18edfde6a450f-ab3410393f80408dbc137d5364c7f1c2FakePre-a14221cffa7043fdbf098599f2f62a8e-878018ee31d74941b714ee2fb9e64cc8 private decimal minPrice = 0.01M; private decimal maxPrice = 100.00M;FakePre-6c794ef8122348798643eb82f67b9865-df3620ae6a7e46ffaffe36cee4e00437FakePre-e32316aa3a184361b1c4171f079d9bed-05bfe3797f5344da9bcc18da10b5681c
(Code Snippet – ASP.NET MVC 3 Custom Validation – Ex1 Custom Range Validation Thresholds - VB)
Imports System
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The values of minPrice and maxPrice are initialized here, but they could be retrieved from a database query or a Web Service call, making the application more maintainable.
Implement a class initializer and the method IsValid from the base class. This step is required for custom validation at server side:
(Code Snippet – ASP.NET MVC 3 Custom Validation – Ex1 Custom Range Validation IsValid- CSharp)
using System;
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(Code Snippet – ASP.NET MVC 3 Custom Validation – Ex1 Custom Range Validation IsValid- VB)
Imports System
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End Function
End Class
Task 2 – Creating the Custom Data Annotation
In this task, you will add a new data annotation tag to the Album class that will be automatically linked to the validation method just created:
- Open the Album.[cs|vb] file at MvcMusicStore\Models.
Add Validations namespace into the Album class
using MvcMusicStore.Validations;
Imports MvcMusicStore.Validations
Replace current data annotation with the PriceValidation attribute:
[Range(0.01, 100.00, ErrorMessage = "Price must be between 0.01 and 100.00")]
[PriceValidation]
<Range(0.01, 100.00, ErrorMessage: = "Price must be between 0.01 and 100.00")>
<PriceValidation()>
After the replacement, the Album.[cs|vb] file should look like the following:
namespace MvcMusicStore.Models { [MetadataType(typeof(AlbumMetaData))] public partial class Album { // Validation rules for the Album class ... [Required(ErrorMessage = "Price is required")] [PriceValidation] public object Price { get; set; } } }
<MetadataType(GetType(Album.AlbumMetaData))> Partial Public Class Album 'Validation rules for the Album class ... <Required(ErrorMessage:="Price is required"), PriceValidation()> Public Property Price As Object End Class
Task 3 – Running the Application
In this task, you will test that the StoreManager Create View template validates the price using custom validation.
- Press F5 to run the Application.
The project starts in the Home page. Browse /StoreManager/Create and click Save without filling the form to verify that you get the price range validation message:
Figure 1
Validating an album price
Next Step
Exercise 2: Adding validation at client side