added locations and countries queries

backend/WebSem/WebApiWebSem/DataAccess/DbPediaDataAccess.cs

                 }
                 else
                 {
-                    dbo.Fields.Add(new ArticlesFieldsDbo
+                    if (data != null)
                     {
-                        Property = variable,
-                        Type = "text/plain",
-                        Value = data
-                    });
+                        dbo.Fields.Add(new ArticlesFieldsDbo
+                        {
+                            Property = variable,
+                            Type = "text/plain",
+                            Value = data
+                        });
+                    }
                 }
             }
             return dbo;
         public LuResult<LuPaginatedDbo<ArticlesDbo>> GetMultiple(LuPaginatedRequestDbo request)
         {
             var type = ArticlesDataAccess.GetFilterType(request.Filter);
-            string query = null;
             string querySelect = null;
             string queryWhereId = null;
             string queryWhereVars = null;
                 queryWhereId = @"?id rdf:type dbo:Person ;
 ?type dbr:World_War_II .";
                 queryWhereVars = @"
+?id dbp:name ?name .
 OPTIONAL { ?id dbo:abstract ?abstract FILTER(lang(?abstract) = 'en') }
 OPTIONAL { ?id foaf:depiction ?pictureUrl }
 OPTIONAL { ?id dbpedia-owl:depictionDescription ?pictureDesc }
-OPTIONAL { ?id dbp:name ?name . FILTER (lang(?name) = 'en') }
 OPTIONAL { ?id dbp:birthDate ?birthDate }
 OPTIONAL { ?id dbp:deathDate ?deathDate }
-BIND (CONCAT(?abstract, ' ', ?id) AS ?search)";
+FILTER (lang(?name) = 'en')
+BIND (CONCAT(?name) AS ?search)";
+            }
+            else if (type == "locations")
+            {
+                querySelect = "?id ?name ?abstract ?pictureUrl ?pictureDesc (str(MIN(?date) as ?date) as ?date) (group_concat(distinct ?combatant;separator=', ') as ?combatant) (group_concat(distinct ?commanderName;separator=', ') as ?commander)";
+                queryWhereId = @"?ww foaf:isPrimaryTopicOf wikipedia-en:World_War_II ;
+dbo:place ?id.";
+                queryWhereVars = @"
+?id foaf:name ?name .
+OPTIONAL { ?id dbo:abstract ?abstract FILTER(lang(?abstract) = 'en') }
+OPTIONAL { ?id foaf:depiction ?pictureUrl }
+OPTIONAL { ?id dbpedia-owl:depictionDescription ?pictureDesc }
+OPTIONAL { ?id dbo:date ?date }
+OPTIONAL { ?id dbp:combatant ?combatant }
+OPTIONAL { ?id dbp:commander ?commanderName }
+FILTER (lang(?name) = 'en')
+BIND (CONCAT(?name) AS ?search)";
+            }
+            else if (type == "countries")
+            {
+                querySelect = "?id (MIN(?name) as ?name) ?abstract ?pictureUrl ?pictureDesc ";
+                queryWhereId = @"?id a <http://dbpedia.org/ontology/Country> ;
+?type dbr:World_War_II .";
+                queryWhereVars = @"
+?id foaf:name ?name .
+OPTIONAL { ?id dbo:abstract ?abstract FILTER(lang(?abstract) = 'en') }
+OPTIONAL { ?id foaf:depiction ?pictureUrl }
+OPTIONAL { ?id dbpedia-owl:depictionDescription ?pictureDesc }
+FILTER (lang(?name) = 'en')
+BIND (CONCAT(?name) AS ?search)";
             }
 
             var filter = $"FILTER regex(?search, '{request.Filter.Query}', 'i')";
 
             var count = Query(string.Format(@"{0}
 SELECT (COUNT(?id) AS ?count) WHERE {{
-{1}
+SELECT DISTINCT {1} WHERE {{
 {2}
 {3}
+{4}
+}}
 }}
-", Prefixes, queryWhereId, queryWhereVars, filter));
+", Prefixes, querySelect, queryWhereId, queryWhereVars, filter));
             if (!count)
             {
                 return count.To<LuPaginatedDbo<ArticlesDbo>>();