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Multiple Models in a View in ASP.NET MVC 4 / MVC 5

Snesh Prajapati

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3 Nov 2014

Using Multiple Models in a View in ASP.NET MVC 4

Introduction

When I was a beginner for ASP.NET MVC, I faced a question many times: how many ways do you know to use/pass multiple models in/to a view? At that time, I knew only two ways, then I learned some other ways to achieve the same. In this article, I will share my learning so far. Hope it will be helpful for others.

Pre-requisite: you should be at intermediate level with C# and ASP.NET MVC. If you are absolute new to C# and ASP.NET MVC, please look for other resources to understand terms used here. You can put comment below article in case you need any detail. I will be happy to help. Thanks.

There are many ways of using multiple models in a view, most frequently used are given below:

ViewData
ViewBag
PartialView
TempData
ViewModel
Tuple

All the above ways of using multiple models in view have their place but we need to think and pick which one fits our requirements. All techniques have their own advantages and disadvantages and we have such discussion in another article How to Choose the Best Way to Pass Multiple Models.

To understand the article better, please download the attached code, have an overview of the code, then follow the steps given in this article.

Overview of Sample Demo

The attached code solution has six views demonstrating the following:

How to pass multiple models using ViewData
How to pass multiple models using ViewBag
How to pass multiple models using PartialView
How to pass multiple models using TempData
How to pass multiple models using ViewModel
How to pass multiple models using Tuple

In the sample demo, all views will have similar HTML structure to get same layout but implementation to pass models to the view will be different.

Structure of the HTML tags is shown below only code inside the scripts tag will be changed as per the scenarios.

HTML Layout of Views

Output of all demos will be similar to the screenshot shown below:

HTML Layout of Views

Creating Basic Structure of Sample Demo

Let's get started by creating a sample demo application. Follow the below steps:

Open Visual Studio 2012, select ASP.NET MVC4 Web Application template and give it project name as MultipleModelDemo and click OK. If you are using Visual Studio 2013 and MVC 5, Please look into the Update for VS 2013 / MVC 5 section below.
Select a template as Basic application then click OK. Visual Studio adds a MultipleModelDemo project in solution as shown below in screenshot.

Right click on the Models folder, add a Models.cs file. Now we need to add three models named as Course, Faculty and Student by writing the following code as shown below:

public class Course
{
    public int CourseId { get; set; }
    public string CourseName { get; set; }
}

public class Faculty
{
    public int FacultyId { get; set; }
    public string FacultyName { get; set; }
    public List<Course> AllotedCourses { get; set; }
}

public class Student
{
    public int EnrollmentNo { get; set; }
    public string StudentName { get; set; }
    public List<Course> EnrolledCourses { get; set; }
}

Add a class file under the Models folder named as Repository.cs file, which will have the implementation of methods to get hardcoded data for application in order to keep it convenient.

Following is the code for GetCourse method which will return a list of courses:

public List<Course> GetCourses()
{
    return new List<Course> { 
        new Course () {  CourseId = 1, CourseName = "Chemistry"}, 
        new Course () {  CourseId = 2, CourseName = "Physics"},
        new Course () {  CourseId = 3, CourseName = "Math" },
        new Course () {  CourseId = 4, CourseName = "Computer Science" }
    };
}

Following is the code GetFaculties method which will return a list of faculties:

public List<Faculty> GetFaculties()
{
    return new List<Faculty> {                 
        new Faculty () {  FacultyId = 1, FacultyName= "Prakash",
            AllotedCourses = new List<Course> 
            {new Course () { CourseId = 1, CourseName = "Chemistry"},
                             new Course () { CourseId = 2, CourseName = "Physics"},
                             new Course () { CourseId = 3, CourseName = "Math"},
        }}, 
        new Faculty () {  FacultyId = 2, FacultyName= "Ponty" ,
            AllotedCourses = new List<Course> 
            {new Course () { CourseId = 2, CourseName = "Physics"},
                             new Course () { CourseId = 4, CourseName = "Computer Science"}
        }},
        new Faculty () {  FacultyId = 3, FacultyName= "Methu", 
            AllotedCourses = new List<Course> 
            {new Course () { CourseId = 3, CourseName = "Math"},
                             new Course () { CourseId = 4, CourseName = "Computer Science"}
        }}
    };
}

Following is the code for GetStudents method which will return a list of students:

public List<Student> GetStudents()
{
    List<Student> result = new List<Student> { 
        new Student () { EnrollmentNo = 1, StudentName= "Jim", 
            EnrolledCourses = new List<Course> 
            { new Course () { CourseId = 1, CourseName = "Chemistry"},
                              new Course () { CourseId = 2, CourseName = "Physics"},
                              new Course () { CourseId = 4, CourseName = "Computer Science"}
        }},
        
        new Student () {  EnrollmentNo = 2, StudentName= "Joli",
            EnrolledCourses = new List<Course> 
            { new Course () { CourseId = 2, CourseName = "Physics"} ,
                              new Course () 
                              { CourseId = 4, CourseName = "Computer Science"}
        }},
        
        new Student () {  EnrollmentNo = 3, StudentName= "Mortin",
            EnrolledCourses = new List<Course>
            {  new Course () { CourseId = 3, CourseName = "Math"},
                               new Course () { CourseId = 4, CourseName = "Computer Science"}
        }}
    };
    
    return result;
}

Add a HomeController to Controller folder. We will write the code in HomeController later.

In Shared folder, we will modify the existing code in _Layout.cshtml file. First write the following code in head tag:

 <head>
 <meta charset="utf-8" />
 <meta name="viewport" content="width=device-width" />

@*Referenced  js and css files which comes with template*@
 <script src="~/Scripts/jquery-1.8.2.min.js"></script>
 <link href="~/Content/Site.css" rel="stylesheet" />

 @*Referenced appcss file having custom CSS*@
 <link href="~/Content/appcss/appcss.css" rel="stylesheet" />
 </head>

Write the following code in body tag:

<body>
    @* Define the place for navigation links in left side of the page*@
    <div class="navigationPanel">
        <div style="margin: 40px 25px 2px 25px;">
            <h3>Links to Demostrations</h3>

So far, we have created basic code which we will be using in all scenarios. Further, we will learn each scenario one by one.

Passing Multiple Models using ViewData

ViewData is used to pass data from a controller to a view. ViewData is a dictionary of objects that is a type of ViewDataDictionary class. ViewData is defined as property in ControllerBase class. Values stored in ViewData require typecasting to their datatype in view. The values in ViewData are accessible using a key.

First, create a object of Repository class in HomeController.

Repository _repository = new Repository();

Add the following code in HomeController.

public ActionResult ViewDataDemo()
{
    ViewData["Courses"] = _repository.GetCourses();
    ViewData["Students"] = _repository.GetStudents();
    ViewData["Faculties"] = _repository.GetFaculties();
    return View();
}

Here ViewDataDemo action method will be passing all three models to its view using ViewData.

Add a view named as ViewDataDemo and write the same code as written below in body tag.
```
<body style="background-color: #DBDBB7">
 <h3>Passing Multiple Models using <span class="
 specialText">  <i>ViewData </i>
```
Here we are iterating Course model using ViewData and casting it into a List<Course>.

Inside the body tag, add a script tag and write the following code. Here we would show the table only when user will select a valid course otherwise the facultyDetailSection and studentDetailSection should not be appearing. We are using fadeout and fadeIn function of jQuery for that purpose.

<script>
       $(document).ready(function(){
           $("#facultyDetailSection").fadeOut(0);
           $("#studentDetailSection").fadeOut(0);
       });

       var selectedCourseName;

       $("#sltCourse").change(function () {
           selectedCourseName = $("#sltCourse").val().trim();

           if (selectedCourseName === "Select Course") {
               $("#facultyDetailSection").fadeOut();
               $("#studentDetailSection").fadeOut();
           }
           else {
               getFacultyTable();
               getStudentTable();
               $("#facultyDetailSection").fadeIn();
               $("#studentDetailSection").fadeIn();
           }
       });
</script>

Here on the change event of Course dropdown, we will read the value and confirm if there is a valid selection to display faculties and students. In case of a valid selection, getFacultyTable and getStudentTable function will be executed. Add the following functions in script tag:

    //Create table to display faculty detail
    function getFacultyTable() {         
    $("#facultyDetailTable").empty();
    $("#facultyDetailTable").append("<table id='tblfaculty'  
    class='tableStyle'><tr><th class='tableHeader' style='width:60px;'>
                                        Employee ID </th> 
                                        <th class='tableHeader'>Faculty Name 
                                        </th> </tr> </table>");

    //Get all faculties with the help of model 
    //(ViewData["Faculties"]), and convert data into json format. 
    var allFaculties = @Html.Raw(Json.Encode(ViewData["Faculties"]));

    for (var i = 0; i  < allFaculties.length; i++) {
        var allotedCourses = allFaculties[i].AllotedCourses;
        for (var j = 0; j  < allotedCourses.length; j++) {
            if(allotedCourses[j].CourseName === selectedCourseName)
                $("#tblfaculty").append
                (" <tr> <td class='tableCell'>"  + 
                allFaculties[i].FacultyId 
                    + " </td> <td class='tableCell'>"+
                    allFaculties[i].FacultyName+" </td> </tr>");
        }
    }
}

//Create table to display student detail
function getStudentTable() {
    $("#studentDetailTable").empty();
    $("#studentDetailTable").append(" <table id='tblStudent' 
    class='tableStyle'> <tr> <th class='tableHeader' style='width:60px;'>
                                        Roll No </th> <th 
                                        class='tableHeader'>Student Name 
                                        </th> </tr> </table>");

    //Get all students with the help of model 
    //(ViewData["Students"]), and convert data into json format. 
    var allStudents = @Html.Raw(Json.Encode(ViewData["Students"]));

    for (var i = 0; i  < allStudents.length; i++) {
        var studentCourses = allStudents[i].EnrolledCourses;
        for (var j = 0; j  < studentCourses.length; j++) {
            if(studentCourses[j].CourseName === selectedCourseName)                      
                $("#tblStudent").append(" <tr> 
                <td class='tableCell'>"  + allStudents[i].EnrollmentNo 
                    + " </td> <td  class='tableCell'>
                    "+allStudents[i].StudentName+" </td> </tr>");
        }
    }           
}

Note: As we have mentioned, all view will have same layout so further demos will have almost the same code as you have written in body tag of ViewDataDemo.cshtml file, now in further demos we just need to modify foreach function to fill data in dropdown and two lines of code in getFacultyTable and getStudentTable JavaScript function.

Passing Multiple Models using ViewBag

ViewBag is also used to pass data from a controller to a view. It is a dynamic property which comes in ControllerBase class that is why it doesn’t require typecasting for datatype.

Add the following code in HomeController:

public ActionResult ViewBagDemo()
{
    ViewBag.Courses = _repository.GetCourses();
    ViewBag.Students = _repository.GetStudents();
    ViewBag.Faculties = _repository.GetFaculties();
    return View();
}

Here ViewBagDemo action method will be passing data to view (ViewBagDemo.cshtml) file using ViewBag.

Add a view named as ViewBagDemo. All code will be same as you have written in ViewDataDemo.cshtml file. Just modify input model to foreach function.
```
@*Iterating Course model using ViewBag *@
@foreach (var item in ViewBag.Courses)
{         
    <option>@item.CourseName</option>
```

In script tag, replace the following line of code in getFacultyTable function:

//Get all faculties with the help of model 
// (ViewBag.Faculties), and convert data into json format.                
var allFaculties = @Html.Raw(Json.Encode(ViewBag.Faculties));

Replace the following line of code in getStudentTable function:

//Get all students with the help of model(ViewBag.Students), 
//and convert data into json format.
var allStudents = @Html.Raw(Json.Encode(ViewBag.Students));

Passing Multiple Models using PartialView

Partial view is used where you need to share the same code (Razor and HTML code) in more than one view. For more details about PartialView, please visit here.

In Home controller, add the following code, PartialViewDemo action method will return a view having the list of all courses only. This action method will not have or pass any faculty or student information as of now.
```
public ActionResult PartialViewDemo()
{
    List<Course> allCourse = _repository.GetCourses();
    return View(allCourse);
}            
```
Add a view named as PartialViewDemo. All HTML code will be same as you have written before. Just modify foreach function.
```
@*Iterating Course Model*@
@foreach(var item in Model)
{         
    <option>@item.CourseName
    </option>
```

In script tag, modify getFacultyTable function as written below:

function getFacultyTable() {
		$.ajax({
	        // Get Faculty PartialView
	        url: "/Home/FacultiesToPVDemo",
	    type: 'Get',
	    data: { courseName: selectedCourseName },
	    success: function (data) {
        $("#facultyDetailTable").empty().append(data);
	    },
	    error: function () {
        alert("something seems wrong");
	}
		});
}

Modify getStudentTable function as written below:

    function getStudentTable() {
    $.ajax({
        // Get Student PartialView
        url: "/Home/StudentsToPVDemo",
        type: 'Get',
        data: { courseName: selectedCourseName },
        success: function (data) {
            $("#studentDetailTable").empty().append(data);
        },
        error: function () {
            alert("something seems wrong");
        }
    });
}

Add a new Action method in HomeController as StudentsToPVDemo and add the following code in StudentsToPVDemo action method.

public ActionResult StudentsToPVDemo(string courseName)
{
    IEnumerable <Course> allCourses = _repository.GetCourses();
    var selectedCourseId = (from c in allCourses where 
    c.CourseName == courseName select c.CourseId).FirstOrDefault();
    
    IEnumerable <Student> allStudents = _repository.GetStudents();
    var studentsInCourse = allStudents.Where(s => 
    s.EnrolledCourses.Any(c => c.CourseId == selectedCourseId)).ToList();
    
    return PartialView("StudentPV", studentsInCourse); 
}

Add a PartialView to the Shared folder by right clicking on StudentsToPVDemo action method, give it name as StudentPV. StudentsToPVDemo action will return StudentPV PartialView having the list of students studying in a particular course.

Add the following code in StudentPV.cshtml file.

@model  IEnumerable <MultipleModelDemo.Models.Student>
 <table id="tblFacultyDetail" class="tableStyle">
         <tr>
         <th class="tableHeader" style="width:60px;">Roll No </th>

Add a new action method to call PatialView for faculties in HomeController. Name it as FacultiesToPVDemo and add the following code:

public ActionResult FacultiesToPVDemo(string courseName)
{
    IEnumerable <Course> allCourses = _repository.GetCourses();
    var selectedCourseId = (from c in allCourses where 
    c.CourseName == courseName select c.CourseId).FirstOrDefault();
    
    IEnumerable <Faculty> allFaculties = _repository.GetFaculties();
    var facultiesForCourse = allFaculties.Where(f => 
    f.AllotedCourses.Any(c =>  c.CourseId == selectedCourseId)).ToList();
    
    return PartialView("FacultyPV", facultiesForCourse);
  }

Add a PartialView named as FacultyPV as we did for student PartialView, write the same code as you have written in StudentPV.cshtml file. Just replace one line of code as:
```
@model  IEnumerable<MultipleModelDemo.Models.Faculty>
```
FacultiesToPVDemo action will return FacultyPV PartialView having the list of faculties who teach a particular course.

Passing Multiple Models using TempData

TempData is a dictionary of objects that is a type of TempDataDictionary class. TempData is defined as property in ControllerBase class. Values stored in TempData require typecasting to datatype in view. The values in TempData are accessible using a key. It is similar to ViewData but the difference is that it allow us to send and receive the data from one controller to another controller and from one action to another action. It’s all about possible because it internally uses session variables.

For more information about TempData, please visit here. Here, we will use TempData only to hold (at server side HomeController) and pass (to the TempDataDemo.cshtml) List of Courses.

In home controller, add the following code:

public ActionResult TempDataDemo()
{
    // TempData demo uses repository to get List<courses> only one time
    // for subsequent request to get List<courses> it will use TempData
    TempData["Courses"] = _repository.GetCourses();

    // This will keep Courses data untill next request is served
    TempData.Keep("Courses");
    return View();
}

Using TempData, we can pass values from one action to another action. TempData["Courses"] having the list of course. We will access this list in FacultiesToTempDataDemo action as shown below:

public ActionResult FacultiesToTempDataDemo(string courseName)
{
    var allCourses = TempData["Courses"] as IEnumerable <Course>;
    
    // Since there are two AJAX call on TempDataPage
    // So we keep to keep Courses data for the next one
    TempData.Keep("Courses");
    var selectedCourseId = (from c in allCourses where 
    c.CourseName == courseName select c.CourseId).FirstOrDefault();
    
    IEnumerable <Faculty> allFaculties = _repository.GetFaculties();
    var facultiesForCourse = allFaculties.Where(f => 
    f.AllotedCourses.Any(c => c.CourseId == selectedCourseId)).ToList();
    
    return PartialView("FacultyPV", facultiesForCourse);
}

public ActionResult StudentsToTempDataDemo(string courseName)
{
    var allCourses = TempData["Courses"] as IEnumerable <Course>;
    
    // If there is change in course again...it may cause more AJAX calls
    // So we need to keep Courses data
    TempData.Keep("Courses");
    
     var selectedCourseId = (from c in allCourses where 
     c.CourseName == courseName select c.CourseId).FirstOrDefault();
     
    IEnumerable <Student> allStudents = _repository.GetStudents();
    var studentsInCourse = allStudents.Where(s => 
    s.EnrolledCourses.Any(c => c.CourseId == selectedCourseId)).ToList();
    
    return PartialView("StudentPV", studentsInCourse);
}

Add a view by right clicking on TempDataDemo action method. Write the same code as you have written in PartialViewDemo.cshtml. Only one line of code needs to modify as written below:
```
@*Iterating Course model using TempData["Courses"] *@
@foreach (var item in TempData["Courses"] 
	as List <MultipleModelDemo.Models.Course>)
{         
    <option>@item.CourseName </option>
```
Modify url in getFacultyTable and getStudentTable function respectively as written below:
```
url: "/Home/FacultiesToTempDataDemo",
url: "/Home/StudentsToTempDataDemo",            
```
Both Action methods FacultiesToTempDataDemo and StudentsToTempDataDemo will return the same PartialView which we used for PartialView demo.

Passing Multiple Models using ViewModel

ViewModel is a pattern that allow us to have multiple models as a single class. It contains properties of entities exactly need to be used in a view. ViewModel should not have methods. It should be a collection of properties needed for a view.

We have three models (classes) named as Student, Course and Faculty. All are different models but we need to use all three models in a view. We will create a ViewModel by adding a new folder called ViewModels and add a class file called ViewModelDemoVM.cs and write the following code as shown below:
```
public class ViewModelDemoVM
{        
    public List <Course> allCourses { get; set; }
    public List <Student> allStudents { get; set; }
    public List <Faculty> allFaculties { get; set; }
}            
```
Note: As a good practice when you create any ViewModel, it should have suffix as VM or ViewModel.

In the HomeController, add the following code:

public ActionResult ViewModelDemo()
{
    ViewModelDemoVM vm = new ViewModelDemoVM();
    vm.allCourses = _repository.GetCourses();
    vm.allFaculties = _repository.GetFaculties();
    vm.allStudents = _repository.GetStudents();

    return View(vm);
}

ViewModelDemo is an action method that will return a view having ViewModelDemoVM which has lists of all Courses, Faculties and Students.

Right click on ViewModelDemo to add a view is called ViewModelDemo. ViewModelDemo.cshtml view will use ViewModelDemoVM as Model as shown below:
```
@model MultipleModelDemo.ViewModel.ViewModelDemoVM            
```

Modify foreach function.

@*Iterating Course ViewModel *@
@foreach (var item in Model.allCourses)
    {         
        <option>@item.CourseName</option>

Replace the following line of code in getFacultyTable function:

//Get all faculties with the help of viewmodel
//(Model.allFaculties), and convert data into json format.
var allFaculties = @Html.Raw(Json.Encode(Model.allFaculties));

Replace the following line of code in getStudentTable function:

//Get all students with the help of viewmodel(Model.allStudents), 
//and convert data into json format.
var allStudents = @Html.Raw(Json.Encode(Model.allStudents));

Passing Multiple Models using Tuple

Tuple is a new class introduced in .NET Framework 4.0. It is an ordered sequence, immutable, fixed-size collection of heterogeneous (allows us to group multiple kind of data types) objects.

Add the following code in Home controller.

public ActionResult TupleDemo()
{
    var allModels = new Tuple <List <Course>, 
    List <Faculty>,  List <Student>>
    (_repository.GetCourses(), _repository.GetFaculties(),  _repository.GetStudents()) { };
     return View(allModels);
}

Here, we are defining a tuple which is having lists of courses, faculties and students. We are passing this tuple to the View.

Add a View named as TupleDemo. Write code as you have written in ViewModelDemo.cshtml file. Just need to replace few lines of code. Replace model declarations as shown below. Here, we will use the namespace used to avoid long fully qualified class names.
```
@using MultipleModelDemo.Models;
@model Tuple <List <Course>, List <Faculty>, List <Student>>            
```

Modify foreach function:

@*Iterating Course model using tuple *@
@foreach (var item in Model.Item1)
    {         
         <option>@item.CourseName </option>

Here Model.Item1 is mapped to Course model.

Inside the JavaScript function called getFacultyTable replace the following line of code:
```
var allFaculties = @Html.Raw(Json.Encode(Model.Item2));            
```
Here Model.Item2 is mapped with Faculty model.
Inside the JavaScript function called getStudentTable, replace the following line of code:
```
var allStudents = @Html.Raw(Json.Encode(Model.Item3));            
```
Here Model.Item3 is mapped with Student model.

Update for VS 2013 / MVC 5

If you would like to use Visual Studio 2013 / MVC 5, Step 1 and 2 as given for MVC 4 would be different, So please follow the steps as given below and then start from steps 3 as given for MVC 4 above.

Open Visual Studio 2013, Click on "New Project" and select ASP.NET Web Application template and give it project name as MultipleModelDemo and click OK.
Select a template as MVC and make sure that all check box given in lower section of popup are unchecked other than MVC. Before clicking OK, we need to change Authentication (since for this demo we are not using either Authentication or Unit Tests to keep it simple and to the point). Please find screen shots below for the same:

Changing the Authentication from "Individual User Account" to "No Authentication":

Visual Studio adds a MultipleModelDemo project in solution. Now you can follow the step 3 and further as given for MVC 4.

Conclusion

In this article, we learned how to use multiple models in a view. In the article How to Choose the Best Way to Pass Multiple Models, I have shared my findings about when and where to pick a particular way to use multiple models in a view. Your inputs and queries are most welcome. Thanks.

License

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