PREFIX foaf:       <http://xmlns.com/foaf/0.1/>
PREFIX dct:        <http://purl.org/dc/terms/>
PREFIX schema:     <https://schema.org/>

CONSTRUCT
{
    GRAPH ?graph
    {
        ?graph dct:title ?categoryName ;
            foaf:primaryTopic ?category .

        ?category a schema:ProductGroup ;
            dct:title ?categoryName ;
            dct:description ?description ;
            schema:name ?categoryName ;
            schema:identifier ?categoryID ;
            schema:description ?description ;
            foaf:depiction ?picture .
    }
}
WHERE
{
    ?category_row <#categoryID> ?categoryID ;
        <#description> ?description ;
        <#categoryName> ?categoryName ;
        <#pictureHash> ?pictureHash .

    BIND(uri(concat(str($base), "categories/")) AS ?container)
    BIND(uri(concat(str(?container), encode_for_uri(?categoryID), "/")) AS ?graph)
    BIND(uri(concat(str(?graph), "#this")) AS ?category)
    BIND(uri(concat(str($base), "uploads/", encode_for_uri(?pictureHash))) AS ?picture)
}