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"]