Hey!
I'm play today a little bit with umbraco to learn it with c#. After little start errors run the system now and i can work with that in Visual Studio. But now i have try to create a new "partial view" for the navigation with the template code, but if i reload the page they print errors. I understand the errors but i don't know what i can do for fix.

Errors:

"IPublishedContent" does not contain a definition for "content", and no accessible content extension method could be found that accepts an initial argument of type "IPublishedContent" (possibly missing a using directive or assembly reference).

@{ var selection = Model?.Content.Root().Children.Where(x => x.IsVisible(PublishedValueFallback)).ToArray(); }

 "IPublishedContent" enthält keine Definition für "Content", und es konnte keine zugängliche Content-Erweiterungsmethode gefunden werden, die ein erstes Argument vom Typ "IPublishedContent" akzeptiert (möglicherweise fehlt eine using-Direktive oder ein Assemblyverweis).

    @if (selection?.Length > 0)
    {
        <ul>
            @foreach (var item in selection)
            {
                <li class="@(item.IsAncestorOrSelf(Model?.Content) ? "current" : null)">
                    <a href="@item.Url(PublishedUrlProvider)">@item.Name</a>
                </li>
            }
        </ul>
    }

Argument "1": Conversion from "method group" to "object?" not possible.

@if (selection?.Length > 0)
{
    <ul>
        @foreach (var item in selection)
        {
            <li class="@(item.IsAncestorOrSelf(Model?.Content) ? "current" : null)">
                <a href="@item.Url(PublishedUrlProvider)">@item.Name</a>
            </li>
        }
    </ul>
}

Code:

@inherits Umbraco.Cms.Web.Common.Views.UmbracoViewPage
@using Umbraco.Cms.Core
@using Umbraco.Cms.Core.Models.PublishedContent
@using Umbraco.Cms.Core.Routing
@using Umbraco.Extensions

@inject IPublishedValueFallback PublishedValueFallback
@inject IPublishedUrlProvider PublishedUrlProvider
@*
    This snippet displays a list of links of the pages immediately under the top-most page in the content tree.
    This is the home page for a standard website.
    It also highlights the current active page/section in the navigation with the CSS class "current".
*@

@{ var selection = Model?.Content.Root().Children.Where(x => x.IsVisible(PublishedValueFallback)).ToArray(); }

@if (selection?.Length > 0)
{
    <ul>
        @foreach (var item in selection)
        {
            <li class="@(item.IsAncestorOrSelf(Model?.Content) ? "current" : null)">
                <a href="@item.Url(PublishedUrlProvider)">@item.Name</a>
            </li>
        }
    </ul>
}

System:

• Operating system name Microsoft Windows 11 Pro Insider Preview
• Processor AMD Ryzen 5 3500X 6-Core Processor, 3593 MHz, 6 core(s), 6 logical processor(s)
• Microsoft Visual Studio Community 2022 Version 17.3.1 VisualStudio.17.Release/17.3.1+32811.315 Microsoft .NET Framework Version 4.8.09032
  Version installed: Community
  ASP.NET and Web Tools 17.3.375.53775
  ASP.NET and Web Tools
  C#-Tools 4.3.0-3.22401.3+41ae77386c335929113f61d6f51f2663d2780443
  C# components used in the IDE. Depending on your project type and related settings, a different version of the compiler may be used.