How to Choose the Best Way to Pass Multiple Models in ASP.NET MVC

Snesh Prajapati, 8 Dec 2014

http://www.codeproject.com/Articles/717941/How-to-Choose-the-Best-Way-to-Pass-Multiple-Models

Introduction

In this article, we will discuss how to choose the most suitable way to pass multiple models from controller to view in ASP.NET MVC. We have seen 6 such approaches, i.e., ViewModel, Patial View, Tuple, ViewData, ViewBagand TempDatain the previous article "Using Multiple Models in a view in ASP.NET MVC4". We may get confused while selecting a way to be used in a particular scenario. In this article, I will share my findings on this topic.

If you have not read our previous article on Using Multiple Models in a view in ASP.NET MVC4, please have a look because the current article is based on that. The previous article has detailed discussion on how we can pass multiple models from controller to view along with a demo application in ASP.NET MVC 4. It will help you to understand the current article better.

Overview of Approaches

All six approaches described in the previous article have their own pros and cons. What to pick when depends upon the specific scenario in hand and obviously it is a debatable topic. Before taking any decision, we need to identify the requirement exactly then only we should choose one of those approaches by comparing the pros and cons. In this article, I would like to arrange those approaches from most to least frequently used in ASP.NET MVC applications as given below:

ViewModel

Partial View

ViewBag

ViewData

TempData

Tuple

An application can use more than one approach based on the requirement at a particular point. We need to consider the best one as per the current need.
Now we will discuss the above approaches, their usages, associated pros and cons in detail.

ViewModel

ViewModel is a pattern that allow us to have multiple models as a single class. It aggregates models or contains their properties exactly as per the need of a view. ViewModel should not have methods. It should be a collection of properties needed for a view.

Typical Usages

It is the most widely used approach to pass multiple models to View in enterprise applications. It is the standard way you can use when you need to display multiple models in the view (applicable in case of partial view too).

Advantages

ViewModel allows us to render multiple model types in a View as a single model.

Great intellisense support and compile time error checking on View page.

ViewModel is good for security purpose also as Views have only what they exactly need. Core domain models are not exposed to user.

If there is any change in core domain model, you do not need to change anywhere in View code, just you need to modify corresponding ViewModel.

In this way, ViewModel promotes loose coupling in application.

Disadvantages

ViewModels add another layer between Models and Views so it increases the complexity a little bit. So for small and demo applications, we can use tuple or other ways to keep the things simple for demo.

Partial View

A Partial View is a sub-view that you can include in a parent view. In many cases, we have a situation where many Views have shared/common presentation, that common presentation is separated into a Partial View and used in other Views.

Typical Usages

This approach is also frequently used in enterprise applications along with ViewModels. It is used where you need to share the same code (Razor and HTML code) in more than one View.

Advantages

It promotes reusability of code (Razor and HTML code) in application.

It is very helpful for single page applications

You can use ViewModel approach to Partial View too.

Using Partial View, you can update a particular area of a View without refreshing the whole page using AJAX.

Disadvantages

If used excessively, then View becomes a just aggregation of Partial Views, so sometime readability is compromised.

ViewBag

ViewBagis a dynamic property which comes from

ControllerBase

class. Internally

ViewBag

properties are stored as name/value pairs in the dictionary. It takes advantage of the new dynamic features in C# 4.0 so

ViewBag

doesn’t require typecasting for data types.

Typical Usages

ASP.NET MVC 3.0 and latest versions, it is supposed to be used where a property is directly associated to View and do not fit as a model (a model is supposed to be a class encapsulating business data and behaviors). Typical examples of

ViewBag

are to set the title of a View using

ViewBag.Title

, or display some message in View as

ViewBag.Message

, etc.

Advantages

Using

ViewBag

, we can send data from controller to view with minimal efforts.

Syntax of

ViewBag

is better than

ViewData

. No need to use key.

ViewBag

doesn’t require type casting for data types.

Disadvantages

It is meant for transferring data one-way only that is from controller to view.

The value of

ViewBag

persists only during current request. Its value cannot persist between requests so if redirection occurs, then its value becomes

null

.

It is certainly a bad practice to overuse

ViewBag

. It is not recommended in enterprise application, even though sometime it may use to transfer small data.

No intelligence support and compile-time error checking.

Technically speaking, it is slow as compared to

ViewData

but in real world scenarios, the difference is just negligible. (And at first place, micro optimization is bad.)

ViewData

ViewData

is defined as property (type of

ViewDataDictionary

class) in

ControllerBase

class. Values stored in

ViewData

require typecasting to their datatype in View. The values in

ViewData

are accessible using a key.

Typical Usages

In ASP.NET MVC version 1 and 2, it is used for the same purpose as

ViewBag

. Microsoft is supporting

ViewData

for newer version but as

ViewBag

is providing more benefits, it is better not to use

ViewData

with latest versions of MVC.

Advantages

Using

ViewData

, we can send data from controller to view with inbuilt feature using keys.

Disadvantages

It is meant for transferring data one-way only that is from controller to view.

The value of

ViewData

persists only during current request. Its value cannot persist between requests so if redirection occurs, then its value becomes

null

.

It is certainly a bad practice to overuse

ViewData

. It is not recommended in enterprise application, even though sometime it may use to show small data.

Use key syntax, so not as readable as

ViewBag

which uses property style syntax.

No intelligence support and compile-time error checking.

TempData

TempData

is defined as property in

ControllerBase

class. It is a type of

TempDataDictionary

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 is possible because it internally uses session variables.

Typical Usages

Whenever you need to hold some information till subsequent request, it is good to use

TempData

. It should be used when you need to hold some information like validation messages, error message or some small data which are not having any sensitive information. As it maintains the session to pass value, you should not keep sensitive data in

TempData

.

Advantages

You can pass value from one action to another action or one controller to another controller.

Disadvantages

It may introduce security risk as described above.

It requires type casting for data type and check for

null

values to avoid error.

No intellisense support in Visual Studio.

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.

Typical Usages

It may be good for small and demo applications.

Tuple

is a feature of C# language meant for specific scenarios (described here), but if you are using it in ASP.NET MVC, you should use

Tuple

only when you do not want to create

ViewModel

.

Advantages

It provides a way to aggregate models without creating new class (

ViewModel

)

A quick remedy and need less coding efforts than

ViewModel

Disadvantages

Tuples is fixed size maximum limit of 8 items.

Value is passes as

item1

,

item2

.....It is difficult to identify the arguments just by seeing the code.

Not a great intellisense support in Visual Studio.

Conclusion

In this article, we learned how to choose the best way to pass multiple models in ASP.NET MVC application. I hope this article will help you to understand and use those concepts in your applications in an efficient way. Your queries and comments are most welcome in this respect. Thanks.

References

[1] http://stackoverflow.com/questions/664205/viewmodel-best-practices

[2] http://www.codeproject.com/Articles/193537/C-4-Tuples

[3] http://stackoverflow.com/questions/1500402/when-to-use-tempdata-vs-session-in-asp-net-mvc

[4] http://www.webcodeexpert.com/2013/12/what-is-use-of-viewbag-viewdata-and_3.html