Newbie python RESULTS BINDINGS question

I'm using python with SPARQLWrapper and it has worked until now -- I'm not able to add a new SPARQL object to my results.

Here is my working snippet:

 else:

      for result in results["results"]["bindings"]:
          project = result["project"]["value"].encode('utf-8')
          filename = result["filename"]["value"].encode('utf-8')
          keywords = result["keywords"]["value"].encode('utf-8')
          url = result["url"]["value"].encode('utf-8')
          url = result["url"]["value"].encode('utf-8')

          print "<p class=\"results\"><span>Project</span>: %s</p><p class=\"indent\"><span>Filename</span>: %s</p><p class=\"indent\"><span>URL</span>:<a href=\"%s\">%s</a></p><p class=\"indent-bottom\"><sp开发者_Go百科an>Keywords</span>: %s</p> " % \
                (project,filename,url,url,keywords)

I'm trying to add more results. I've tested the SPARQL query as added to the script, I add the object of the query ("parameter") as a RESULTS and BINDINGS pair, I add the %s to print and add the result name to the parens below the print command (not sure what to call that area). So after doing what I did before to add these results, I get the white screen of death -- the header of the page only is written out and the apache error log gives me a KeyError, project = result["project"]["value"].encode('utf-8').

Here is an example of an added element that breaks the script:

  else:
      print "<h1>ASDC RDF Search Results</h1>"
      print "<p class=\"newsearch\"><a href=\"/asdc.html\">new search | <a href=\"http://localhost/asdc.html\">About this project</a></p><div style=\"clear:both;\"</div>"
      for result in results["results"]["bindings"]:
          project = result["project"]["value"].encode('utf-8')
          filename = result["filename"]["value"].encode('utf-8')
          url = result["url"]["value"].encode('utf-8')
          url = result["url"]["value"].encode('utf-8')
          keywords = result["keywords"]["value"].encode('utf-8')
          parameter = result["parameter"]["value"].encode('utf-8')

          print "<p class=\"results\"><span>Project</span>: %s</p><p class=\"indent\"><span>Filename</span>: %s</p><p class=\"indent\"><span>URL</span>:<a href=\"%s\">%s</a></p><p class=\"indent\"><span>Keywords</span>: %s</p><p class=\"indent-bottom\"><span>Parameter</span>: %s</p> " % \
                (project,filename,url,url,keywords,parameter)

So two questions: Is the error obvious? Am I screwing up the formatting in the keys somehow when I add the new line? Also, does python write errors to a log or can I enable that? Thanks...

Edit: Here's the query including parameter (it works, tested directly in the Fuseki UI)

PREFIX e1: <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/>

  SELECT ?url ?filename ?keywords ?project ?parameter

  WHERE {
    ?s <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/url> ?url. 
    ?s <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/filename> ?filename. 
OPTIONAL {
        ?s <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/keywords> ?keywords.
        ?s <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/project> ?project.
        ?s <http://data.gov/source/work/dataset/gov/vocab/enhancement/1/parameter> ?parameter.
        }
         FILTER (regex(?keywords, "FILTER-STRING", "i") || regex(?url, "FILTER-STRING", "i") || regex(?filename, "FILTER-STRING", "i")) .

}

First query is similar minus the ?parameter. FILTER-STRING comes from my cgi form.

---

Either your result dict has no key "project", or the result["project"] dict has no key "value".

So insert

print result.keys()
print result["project"]
print result["project"].keys()
print result["project"]["value"]

imediatly after for result in ... and you see what is going wrong.

---

My issue turned out to be caused by NULL values in my results from the OPTIONAL clause in my query. SPARQLWrapper developers suggested using if-else, as below with example query using OPTIONAL (& it worked for me):

PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
    SELECT ?person ?party
    WHERE { ?person <http://dbpedia.org/ontology/birthPlace> <http://dbpedia.org/resource/Asturias> 
            OPTIONAL { ?person <http://dbpedia.org/property/party> ?party }

for result in results["results"]["bindings"]:
    if result.has_key("party"):
        print "* " + result["person"]["value"] + " ** " + result["party"]["value"]
    else:
        print result["person"]["value"]