How can I check if a linked Component is first in the list?

Question

I have the following syntax in a template using Razor Mediator:

<tcdl:ComponentField name="Fields.contact_nav">
    @foreach (dynamic link in Fields.contact_nav.links) {
        @if(link.IsFirst){...}
    }
</tcdl:ComponentField>

How do I write the link.IsFirst in MVC Razor? I have done the following:

@Html.SiteEditField(Model.Component,Model.Component.Fields["contact_nav"])
@foreach (var link in Model.Component.Fields["contact_nav"].LinkedComponentValues) {
    if(link.EmbeddedValues.First()){...}
}

But it is giving error for EmbeddedValues.

What am I doing wrong? How do I check whether a field is the first in a list or not in MVC Razor?

Answer 1

To expand a little on what your problem is and why your solution won't work; the IsFirst property that you're using is part of the Razor Mediator's DynamicItemFields class and is explicitly set by the library, not a built-in part of any .NET collection type.

By contrast, when you use the Enumerable.First method as in your MVC example, you are not checking if the link is the first in the list, you are querying for the first embedded value in link that matches the provided expression (or in this case, as you pass no expression, the first embedded value in the link field), although since link is probably not an embeddable schema, there likely won't actually be any embedded values (not that it would help you if there were).

The most robust solution is probably just to set a flag:

@{
    bool first = true;
}
@foreach(var link in Model.Component.Fields["contact_nav"].LinkedComponentValues)
{
    if (first)
    {
        first = false;
        ...
    }
}

If you need more sophisticated index-related logic you would probably be better off using a standard for loop rather than a foreach.

@{
    var values = Model.Component.Fields["contact_nav"].LinkedComponentValues;
}

@for(int i = 0; i < values.Count; i++)
{
    if(i == 0)
    {
        ...
    }
}