Model metadata and model template for asp.net MVC: Introducing "ListControl" into asp.net mvc

Not only can we create the appropriate template to control the type of data based on the model metadata in the UI interface rendering methods, but also through some extensions to control the model metadata itself. In some cases, the combination of the two can often solve a lot of special data rendering problems, the example that we will demonstrate next is a typical example.

The traditional asp.net has a set of important control types called list controls (ListControl), and its subclasses include DropDownList, ListBox, RadioButtonList, and CheckBoxList. For ASP.net mvc, we can dropdownlist/dropdownlistfor and listbox/through htmlhelper/htmlhelper<tmodel> extension methods The listbox renders a Drop-down box and a list box on the interface, but we need to manually specify all of the list options included. In general Web applications, especially in enterprise applications, we choose to maintain these lists individually, and if we can eliminate the task of manually providing lists when building a "list control", this will undoubtedly lead to great traversal of development, which is actually easy to implement.

This article supporting source code: http://www.bianceng.net/dotnet/201211/644.htm

First, the effect of implementation

Let's take a look at the effect of the final implementation through this extension. In an empty Web application created through the ASP.net MVC project template for Visual Studio, we define an employee type that represents the employees as model. As shown in the following code snippet, attributes that represent gender, education, department, and skills are applied to Radiobuttonlistattribute, Dropdownlistattribute, Listboxattribute and Checkboxlistattribubte four features. As you can see from the name, these four features represent the form that the target element renders on the UI interface, which corresponds to the four types of list controls in the traditional ASP.net Web application: RadioButtonList, DropdownList, ListBox and CheckBoxList. The string specified in the attribute represents the name of the predefined list.

   1:public class Employee
   2: {
   3:     [DisplayName ("name")]
   4: Public     string Name {get; set;}
   5:
   6:     [RadioButtonList ("Gender")]
   7:     [DisplayName ("gender")]
   8: Public     string Gender {get; set;}
   9:
       [DropdownList ("Education")]
  One:     [DisplayName ("Education")]
  : Public     string Education {get; set;}
  13:
       [ListBox ("Department")]
  :     [DisplayName ("department")]
  : Public     ienumerable<string> Departments {get; set;}
  17:
       [CheckBoxList ("Skill")]
  :     [DisplayName ("good skill")]
  Public     ienumerable<string> Skills {get; set;}
  21:}

In the default HomeController created, we define one of the following index action methods. In this method, we create a specific employee object and set all of its properties accordingly, and eventually render the object in the default view.

   1:public class Homecontroller:controller
   2: {
   3: Public     actionresult Index ()
   4:     {
   5:         Employee employee = new Employee
   6:         {
   7:             Name       = "John",
   8:             Gender     = "M",
   9:             Education  = "M",
               departments= New string[] {"HR", "AD"},
  One:             Skills     = new string[] {"CSharp", "ADONet"}
  :         };
  : Return         View (employee);
  :     }
  15:}

As shown below is the view definition corresponding to the index operation above, which is a strongly typed view with model type as employee, we call htmlhelper<tmodel> Template method editorfor All attributes of the employee object as model will be rendered in edit mode.

 1: @model Employee 
 2: <table> 
 3: <tr> 
 4: <td> @Html. labelfor (M =&G T M.name) </td><td> @Html. Editorfor (M => m.name) </td> 
 5: </tr> 
 6: <tr>< br> 7: <td> @Html. labelfor (M => m.gender) </td><td> @Html editorfor (M => m.gender) </TD&G T 
 8: </tr> 
 9: <tr> 
: <td> @Html. labelfor (M => m.education) </td&         Gt;<td> @Html. Editorfor (M => m.education) </td> 
 One: </tr> 
: <tr> 
 13: <td> @Html. Labelfor (M => m.departments) </td><td> @Html. Editorfor (M => m.departments) </td& Gt Lt;td> @Html. Editorfor (M => m.skills) </td> 
: </tr> 
: </table> 

The following illustration shows the effect of the Web application runtime. As we can see, the four properties are rendered in four different list controls, and the list attributes defined for the four words on them (Radiobuttonlistattribute, Dropdownlistattribute, Listboxattribute and Checkboxlistattribubte).