getLsoaData()

map-manager.js

// get the LSOA data from the database.
var getLsoaData = function(tiles) {

  // define this inside this closure - it's not useful outside the scope of this func
  var buildSparql = function(tile) {

    var lowerLat = tile[0][0];
    var lowerLong = tile[0][1];
    var upperLat = tile[1][0];
    var upperLong = tile[1][1];

    var sparql = "PREFIX geo: <http://www.w3.org/2003/01/geo/wgs84_pos#> " +
    "PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> " +
    "SELECT ?lsoa ?notation ?label ?lat ?long ?score" +
    " WHERE { " +
    "  GRAPH <http://opendatacommunities.org/id/graph/geography/lsoa> { " +
    "    ?lsoa a <http://opendatacommunities.org/def/geography#LSOA> . " +
    "    ?lsoa geo:lat ?lat . " +
    "    ?lsoa geo:long ?long . " +
    "    ?lsoa <http://www.w3.org/2004/02/skos/core#notation> ?notation . " +
    "    ?lsoa rdfs:label ?label . " +
    "  } " +
    "  GRAPH <http://opendatacommunities.org/id/graph/IMD/2010/" + scoreDomain + "> {  " +
    "    ?obs <http://purl.org/linked-data/sdmx/2009/dimension#refArea> ?lsoa . " +
    "    ?obs <http://opendatacommunities.org/def/IMD#" + scoreDomain + "> ?score . " +
    "  } " +
    "  FILTER ( ?lat >= " + lowerLat + " && " +
    "    ?lat < " + upperLat + " && " +
    "    ?long >= " + lowerLong + " && " +
    "    ?long < " + upperLong + " ) . " +
    "}";
    return sparql;

  };

  var noOfTiles = tiles.length;

  // nothing to do.
  if(noOfTiles == 0) {
    $(self).trigger('lsoaDataRetrieved');
  }

  var tilesRetrieved = 0;

  var page = 1;
  var pageSize = 1000;

  var callAjaxSparqlPaging = function(sparql, tile) {
    var queryUrl = "http://opendatacommunities.org/sparql.json?_page=" + page.toString() + "&_per_page=" + pageSize.toString() + "&query=" + encodeURIComponent(sparql);
    window.swirrl.log('about to call', queryUrl);
    $.ajax(
      queryUrl,
      {
        success: function(data, textStatus, jqXHR) {
          var pageOfData = data.results.bindings;
          $.each(pageOfData, function(idx, el){
            var data = {
              uri: el.lsoa['value'],
              label: el.label['value'],
              lat: parseFloat(el.lat['value']),
              lng: parseFloat(el['long']['value']),
              score: parseFloat(el.score['value'])
            }
            var lsoaNotation = el.notation['value'];
            setLsoaData(tile, lsoaNotation, data);
          });

          if (pageOfData.length == pageSize) {
            // this page was full. There might be more.
            page += 1;
            callAjaxSparqlPaging(sparql);
          } else {
            // no more pages.
            tilesRetrieved+=1;
            if (tilesRetrieved == tiles.length) {
              // we've got all the lsoaData.
              $(self).trigger('lsoaDataRetrieved');
            }
          }
        },
        error: function(jqXHR, textStatus, errorThrown) {
          window.swirrl.log("SPARQL Fail: " + errorThrown + " " + textStatus);
          $(self).trigger('dataError');
        },
        dataType: 'json',
        timeout: 10000 // timeout after a short time.
      }
    );
  };

  // for each tile, get all the pages of data.
  $.each(tiles, function(i, tile){
    var sparql = buildSparql(tile);
    callAjaxSparqlPaging(sparql, tile);
  });
};