Sitefinity - HierarchicalTaxonSelector in designer

DESIGNER.ascx:
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<sitefinity:HierarchicalTaxonField ID="FilterCategory" runat="server" DisplayMode="Write" Expanded="false" ExpandText="Add Category" ShowDoneSelectingButton="true" AllowMultipleSelection="false" BindOnServer="false" TaxonomyMetafieldName="Category" WebServiceUrl="~/Sitefinity/Services/Taxonomies/HierarchicalTaxon.svc" TaxonomyId="E5CD6D69-1543-427B-AD62-688A99F5E7D4" />



DESIGNER.cs:
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descriptor.AddComponentProperty("FilterCategory", this.FilterCategory.ClientID);



DESIGNER.js:
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// Called when the designer window gets opened and here is place to "bind" your designer to the control properties
refreshUI: function () {
    var controlData = this._propertyEditor.get_control(); // JavaScript clone of your control - all the control properties will be properties of the controlData too
    controlData.CategoryIdsStr && this.get_FilterCategory().set_value(controlData.CategoryIdsStr.split(','));
},
// Called when the "save" button is clicked. Here you can transfer the settings from the designer to the control
applyChanges: function () {
    var controlData = this._propertyEditor.get_control();
    controlData.CategoryIdsStr = this.get_FilterCategory().get_value() ? this.get_FilterCategory().get_value().join() : "";
},


CONTROL.cs:
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public string CategoryIdsStr { get; set; }
private List<Guid> categoryIds {
    get {
        return CategoryIdsStr.IsNullOrWhitespace() ? new List<Guid>() : CategoryIdsStr.Split(',').Where(o => o.IsGuid()).Select(o => o.ToGuid()).ToList();
    }
}
private string categoryIdFilterClause {
    get {
        var clauses = categoryIds.Select(o => string.Format("Category.Contains(({0}))", o));
        return string.Join(" OR ", clauses);
    }
}

protected override void InitializeControls(GenericContainer container) {
    //NB: uses dynamic LINQ expression as "Intersect" is not implemented on database...
    //This way all filtering is done on DB for performance
    var staffMembers = SitefinityFunctions.GetDynamicContentItems("StaffMembers.Staff");

    if (!categoryIdFilterClause.IsNullOrWhitespace()) {
        staffMembers = staffMembers.Where(categoryIdFilterClause);
    }
}


HELPERS.cs:
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public static IQueryable<DynamicContent> GetDynamicContentItems(string type) {
    var itemType = TypeResolutionService.ResolveType(string.Concat("Telerik.Sitefinity.DynamicTypes.Model.", type));
    return DynamicModuleManager.GetManager().GetDataItems(itemType).Where(o => o.Visible && o.Status == ContentLifecycleStatus.Live);
}

public static Guid ToGuid(this string str) {
    var g = Guid.Empty;
    Guid.TryParse(str, out g);
    return g;
}