Asp.net mvc two-level classification association method example

Front-end view code
<%: Html. DropDownList ("AwardClassMainID", "select") %>

<%: Html. dropDownList ("SubID", new List <SelectListItem >{( new SelectListItem () {Text = "select", Value = "0"}) %>

// Jquery code

$ ("# AwardClassMainID"). change (function (){

Var url = "../AwardSubClasic/GetClasicList/"; // The rule is Controller/method/Parameter

$. GetJSON (url, {firstclassid: $ ("# AwardClassMainID"). val ()}, function (data ){

Certificate ('{subid'}.html ('');

$ ('# Subid'). append ("<optionvalue = 0> select </option> ")

$. Each (data, function (I, item ){

$ ('# Subid'). append ($ ("<option> </option>" pai.val(item.secondclassid#.html (item. ClassName ));

});

});

});

Code in the Controller in the background
// Add level-1 classified data to the view

ViewBag. AwardClassMainID = new SelectList (bll. GetAll (), "ClassID", "ClassName ");

<Summary>

/// Json return data-query the second-level category of this category by category ID

/// </Summary>

/// <Param name = "id"> Level 1 category ID </param>

/// <Returns> </returns>

[HttpGet]

Public JsonResult GetClasicList (string firstclassid)

{

List <TrainingSecondClass> Classlist = m_BLL.GetClassDropDwonList (firstclassid );

Return Json (Classlist. ToList <AwardSubClasic> (), JsonRequestBehavior. AllowGet );

}

Add interface declaration in IBLL
List <TrainingSecondClass> GetClassDropDwonList (string id );

BLL
Public List <TrainingSecondClass> GetClassDropDwonList (stringid)

{

Return repository. GetClassDropDwonList (db, id). ToList <TrainingSecondClass> ();

}

Add implementation methods in repository
Public List <TrainingSecondClass> GetClassDropDwonList (SysEntities db, string FirstClassID)

{

List <TrainingSecondClass> result = new List <TrainingSecondClass> ();

Var n = db. TrainingSecondClass. Where (p => p. FirstClassID = FirstClassID). ToList ();

Foreach (var c in n)

{

Result. Add (new TrainingSecondClass

{// Retrieve the json call data

SecondClassID = c. SecondClassID,

ClassName = c. ClassName

});

}

Return result;

}