Very often you have a list of items, and then a details-page showing just one item. In this example, we'll just use code to do this (so no visual query) - just so you understand the principle. This example even has the list & details view in the same file - but usually you don't want that - so check the next examples afterwards.
@inherits Custom.Hybrid.Razor14
@using ToSic.Razor.Blade
@{
var persons = AsList(App.Data["Persons"]);
// Get the current url params so we can use it and also modify it in details links
var urlParams = CmsContext.Page.Parameters;
// check if we have a url-parameter called "id" with a value
// if we do, switch on showDetails and filter the persons to only one
var urlId = urlParams["id"];
}
@if (!Text.Has(urlId)) {
<h3>List of Persons</h3>
<ul>
@foreach (var person in persons) {
<li>
<a href='@Link.To(parameters: urlParams.Set("id", person.EntityId.ToString()))'>
@person.FirstName @person.LastName
</a>
</li>
}
</ul>
} else {
// find the person with this Id using LINQ
int id = Kit.Convert.ToInt(urlId);
var person = persons.First(p => p.EntityId == id);
<img loading="lazy" src="@person.Mugshot?w=50&h=50&mode=crop" width="50px" style="border-radius: 50%" class="float-left">
<h3>Details of @person.FirstName @person.LastName</h3>
<a href='@Link.To(parameters: urlParams.Remove("id"))'>back to list</a>
}