Now that you have completed the controller and views, let’s proceed with model validations. Creating a Custom Data Annotation Attribute The EmployeeID textbox is made read-only by adding the readonly attribute. The EmployeeID is displayed in a read-only textbox since it’s the primary key. Notice that a ValidationMessageFor() helper is used for FirstName and LastName to display any model validation errors. The markup of the Edit view is shown below: Īs you can see the Edit view uses the LabelFor() and TextBoxFor() helpers to display EmployeeID, FirstName and LastName. In the next section you will build a custom data annotation that adds this validation to the Employee model. Notice that the figure also shows a validation error. The Edit view displays the EmployeeID, FirstName and LastName columns using HTML helpers and submits the form to the Update() action method. Then add the Edit view and design it as shown below. Notice how the ActionLink() helper is used to render the Show link pointing to the Edit action method and also adds the EmployeeID as a route parameter. The following markup shows the for loop that builds the employee list: There is a Show hyperlink for each employee row that points to the Edit() action method. Now, add the Index view and design it as shown in the following figure:Īs you can see the Index view displays a list of Employee records. The Update() method returns the Edit view and passes the same Employee object as its model. A success message is stored in a ViewData variable and is later displayed on the Edit view. The changes are saved to the database using the SaveChanges() method. If Employee is found, its FirstName and LastName properties are changed to reflect the new values submitted by the user. If the model contains valid values it looks for an existing Employee using the Find() method. The Update() method checks whether the Employee model contains valid values or not using the IsValid property of the ModelState. The Edit view submits the form to the Update() action method. The Update() method accepts Employee as its parameter. It then returns the Edit view and passes the selected Employee to the view as its data model. The Edit() method accepts an EmployeeID as its parameter and selects an Employee object based on the supplied EmployeeID. A List of Employee objects is passed to the Index view as its data model. The Index() action method selects all the employee records from the database and returns the Index view. Index(), Edit() and Update() into it as shown below: NorthwindEntities db = new NorthwindEntities() Įmployee obj = db.Employees.Find(e.EmployeeID) Once the data model is in place add a new controller to the project and write three action methods, viz. For the sake of the example developed in this article you need only three: EmployeeID, FirstName and LastName. The following figure shows the Employee model class.Īs you can see, the Employee class has many properties. Creating the Required Model, Views and Controllerīefore you develop a custom data annotation, first of all create a new ASP.NET MVC project and add an entity framework data model for the Employees table of the Northwind database. This article discusses how this task can be accomplished. You can also add client side validation capabilities to your custom data annotation. In such cases you can create a custom data annotation attribute and attach it with a model property. However, at times you need to perform custom validations on the model properties. ASP.NET MVC provides a few data annotations that cover frequently needed validations such as, and. ASP.NET MVC applications can use data annotation attributes to enforce validations on model properties.
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