CODEWITHSUNDEEP
c#asp.netasp.net-mvcvisual-web-developer
DarkLightA
DarkLightA

Reputation: 15662

What does Model.(Variable) do?

Okay, so I've got this code:

    public ActionResult Welcome(string name = "", int numTimes = 1)
    {
        var viewModel = new WelcomeViewModel
        {
            Message = "Hello " + name,
            NumTimes = numTimes
        };

        return View(viewModel);
    }
    public class WelcomeViewModel
    {
        public string Message { get; set; }
        public int NumTimes { get; set; }
    }

and the view in Welcome() is:

<h2>Welcome</h2>

<% for(int i = 0; i < Model.NumTimes; i++) {%>

    <h3><%: Model.Message; %></h3>
<%} %>

Firstly, when I run this, I get an error when running .../Welcome?name=Scott&numtimes=4 saying that in the line

<h3><%: Model.Message; %></h3>

it expects ')'

Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. Compiler Error Message: CS1026: ) expected

why is this?

Secondly what is this whole Model thing? What does it do?

Upvotes: 1

Views: 419

Answers (4)

dahlbyk
dahlbyk

Reputation: 77530

In addition to the misplaced semicolon, make sure your view is defined to inherit from ViewPage<WelcomeViewModel>. This specifies the type that Model has within the view, allowing the compiler to resolve its members (Message, NumTimes).

Upvotes: 0

Guffa
Guffa

Reputation: 700342

It's because the <%: Model.Message; %> translates (basically) into:

Response.Write(Model.Message;);

As you see, the semicolon should not be there. The compiler expects the ending parentheses before there is a semicolon, hence the error message.

The "Model thing" is the M in MVC. The Model is the data that the View displays. Each view has a single Model, so the Model contains all the data that the View needs.

Upvotes: 2

Basic
Basic

Reputation: 26766

With regards to your second question, MVC is a way of separating the logic (in your controller) from the presentation (in your view).

You use the controller to generate a model which contains all the information required by the view.

Eg for a form, the model would have a field for each input. For a table, it would have an IEnumerable<SomeRowClass> etc...

The view itself should do as little processing as possible - simple if statements and loops. all actual logic should be constrained to the controller.

One way to think of it is that a developer writes the controller, a designer writes the view and they collaborate for what goes in the model - designer says "I need to know X,Y,Z" - so the developer adds them to the model and populates the fields as appropriate

As mentioned in the other answer, the semicolon after Model.Message is superfluous.

Upvotes: 0

xandy
xandy

Reputation: 27411

I think you don't need to put the semi-colon after Model.Message.

Model is the reference to what you supplied to your view, in your controller. That's the same instance as what you type return View(viewModel); in your controller.

Upvotes: 2

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