无法在Razor MVC条件下识别HTML语法

Question

Below is the code i am using for one of my mvc views, within the mentioned if condition, html code is not recognized.

<table class="table">
        <tr class="row h4">
            <td>Task</td>
            <td>Parameter</td>
            <td>Active</td>
            <td><input type="button" class="btn btn-default" value="Add Mapping" /></td>
        </tr>
        @foreach (OrderTypeTaskParameterMapping mapping in Model.OrderTypeTaskParameterMappings)
        {
            <tr class="row">
                <td>
                    <select class="form-control">
                        @foreach (Task task in Model.Tasks)
                        {
                            <option value="@task.Id"
                                    @if (mapping.TaskId == task.Id)
                                    {
                                        selected="selected" **doesn't work**
                                    }
                                    >@task.Name</option>
                        }
                    </select>
                </td>
                <td>
                    <select class="form-control">
                        @foreach (Parameter p in Model.Parameters)
                        {
                            <option>@p.Name</option>
                        }
                    </select>
                </td>
                <td>
                    @if (mapping.Active)
                    {
                        <input type="button" class="btn btn-info" value="Active" />
                    }
                    else
                    {
                        <input type="button" class="btn btn-danger" value="InActive" />
                    }
                </td>
                <td><input type="button" class="btn btn-info" value="Save" /></td>
            </tr>
        }
    </table>

On executing the above code i get an error :

What could be the reason? I thought this should have worked. Am i missing something here?

Answer 1

Try this code

<option value="@task.Id" @(mapping.TaskId == task.Id ? "selected" : string.Empty)>

Inside {} you can use only C# code

Answer 2

I think it also works using conditional attributes:

<option value="@task.Id" selected="@(mapping.TaskId == task.Id)">

If the expression evaluates to false , then Razor will not output the selected attribute.

More on conditional attributes

About the original question, I believe the problem is related to how Razor tells HTML from C# blocks. On your code, you are not closing the option tag. You're trying to open it, write (or not) the selected attribute using a code block and then close it.

Inside the code block, Razor's expecting a line of code or a new HTML tag. As it's not an HTML tag (no angle bracket) it tries to interpret it as C#, hence the missing ; message.

That's why the <tr> and <td> tags inside the parent @foreach(){}} are working: because they can be interpreted as new HTML blocks.