Ok,

after some testing I have come with the following solution.

I have created a razor extension method which takes the publishedcontent node and all categories:

    public static bool CheckCategories(this IPublishedContent node, int[] categories)
    {
        if(categories.Length > 0)
        {
            var packages = node.GetPropertyValue<IEnumerable<IPublishedContent>>("packages");

            bool isElement = false;
            foreach(var package in packages)
            {
                isElement = categories.Contains(package.GetPropertyValue<int>("category"));
            }

            return isElement;
        }

        return true;
    }

Then in my view I do:

// Get all sub categories of current primary category
var categories = Model.Content.Children.Select(c => c.Id);

// Get company repository node
var companyRepo = Model.Content.AncestorOrSelf(1).Children.Where(
        c => c.DocumentTypeAlias == "companyRepo"
    ).First();

// Get all companies which are children of one of the sub categories of this primary category
var companies = companyRepo.Children.Where(c => c.CheckCategories(categories.ToArray()));

Will this be good enough in terms of performance when searching over 250 companies in 30 sub categories? Or should I then use something else?

/Michaël

Hi Michaël,

Your query is complicated! You do not need to pick up the "companyRepo" content and then the children. You can search for docType of company.

I've never done a query when it has Nested Content, but I believe it works:

    //Get all sub categories of current primary category
    var categories = Model.Content.Children.Select(c => c.Id);

    //Get all companies which are children of one of the sub categories of this primary category (Current Content)
            var companies = Umbraco.TypedContentAtXPath("//companyDocType")
                .Where(c => c.IsVisible() && c.GetPropertyValue<IEnumerable<IPublishedContent>>("packages")
                .Select(s => s.GetPropertyValue<int>("category")).ContainsAny(categories));

How much performance is a very difficult question. It will depend on several factors, just testing.

Suggestion is to create a way to use Relations

https://our.umbraco.org/documentation/reference/management/services/relationservice

When a company is published, implement the ContentService.Published method where you take the selected subcategories and creates a relationship between the company and the primary category.

https://our.umbraco.org/documentation/reference/events/application-startup

https://our.umbraco.org/documentation/reference/events/contentservice-events

https://our.umbraco.org/documentation/getting-started/Code/Subscribing-To-Events/

You would get the companies on the primary category page using the created relation.

I liked the challenge of your question! I wish I could help more

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