Determine if a JavaScript code in my ASP view will be executed based on control from the controller

Question

Determine if a JavaScript code in my ASP view will be executed based on control from the controller

Working on an ASP.NET MVC4 system, I have a javascript code that displays a performance graph of students when the page loads.

Here is the code for the graph:

<script>
    window.onload = function () {
        var r = Raphael("holder"),
            txtattr = { font: "20px sans-serif" };

        var lines = r.linechart(30, 30, 600, 440,<%= Json.Encode(ViewBag.dates) %>,<%= Json.Encode(ViewBag.Grades)%>, {axisxstep : 6,nostroke: false, axis: "0 0 1 1", symbol: "circle", smooth: false }).hoverColumn(function () {
            this.tags = r.set();
            for (var i = 0, ii = this.y.length; i < ii; i++) {
                this.tags.push(r.tag(this.x, this.y[i], Number(this.values[i]).toFixed(5), 160, 10).insertBefore(this).attr([{ fill: "#fff" }, { fill: this.symbols[i].attr("fill") }]));
            }
        });
</script>

The data for the graph is retrieved from the function DisplayGraph in the controller. See the controller code below:

public ActionResult DisplayGraph(String InputStudent = "IP11")
{
    // Controller logic to fetch data for the graph
}

When a new student joins the school, I want to display a message instead of the graph. How can I control the execution of javascript from the controller?

Any help would be greatly appreciated. Thank you

c#javascript asp.net asp.net-mvc asp.net-mvc-4

Answer 1

Answer №1

Is there a way for my controller to determine when to execute a javascript function and when not to?

One way to do this is through a view model. The view model should contain all the necessary information for rendering the view, including any scripts or links to scripts.

It is recommended to minimize the use of ViewBag and instead use strongly-typed models.

Model

public class MyViewModel {
    public bool DisplayGraph { get; set; }

    public List<object> Data { get; set; }

    public List<int?> Dates { get; set; }

    public List<double> Grades { get; set; }
}

Controller

public ActionResult Index(){

    var model = new MyViewModel();
    model.DisplayGraph = !IsStudentNew();

    // set other properties of the model here, avoiding the use of ViewBag

    return View( model );
}

View

@model MyViewModel

@if( Model.DisplayGraph ){
    <script>
        // javascript for displaying the graph should be placed here
    </script>
}else{
    <div>No statistics available.</div>
}

Answer 2

Is there a way for my controller to determine when to execute a javascript function and when not to?

One way to do this is through a view model. The view model should contain all the necessary information for rendering the view, including any scripts or links to scripts.

It is recommended to minimize the use of ViewBag and instead use strongly-typed models.

Model

public class MyViewModel {
    public bool DisplayGraph { get; set; }

    public List<object> Data { get; set; }

    public List<int?> Dates { get; set; }

    public List<double> Grades { get; set; }
}

Controller

public ActionResult Index(){

    var model = new MyViewModel();
    model.DisplayGraph = !IsStudentNew();

    // set other properties of the model here, avoiding the use of ViewBag

    return View( model );
}

View

@model MyViewModel

@if( Model.DisplayGraph ){
    <script>
        // javascript for displaying the graph should be placed here
    </script>
}else{
    <div>No statistics available.</div>
}

Answer 3

Answer №2

One way to enhance your model is to include a property called GraphText. This property can be displayed on top of the graph. If there are statistics available, you can leave this property empty. However, if there are no statistics, you can assign it a default value:

public class YourModel {
    public IList<Statistic> StudentStatistics { get; set; }
    public string GraphText {
        get {
            return StudentStatistics.Any() ? "" : "No statistics available yet";
        }
    }
}

After updating your model, you can then simply render the GraphText property on top of the graph in your view.

Answer 4

One way to enhance your model is to include a property called GraphText. This property can be displayed on top of the graph. If there are statistics available, you can leave this property empty. However, if there are no statistics, you can assign it a default value:

public class YourModel {
    public IList<Statistic> StudentStatistics { get; set; }
    public string GraphText {
        get {
            return StudentStatistics.Any() ? "" : "No statistics available yet";
        }
    }
}

After updating your model, you can then simply render the GraphText property on top of the graph in your view.

Determine if a JavaScript code in my ASP view will be executed based on control from the controller

Answer №1

Answer №2

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