[mapserver-users] Can't Get Kropla Fifth Map to work Properly

[Robin Pearce]

I am running MapServer 5.4.2 and PHP 5.3.

As a PHP/Mapscript novice, I am using Kropla's Beginning MapServer (2005) to learn what I need to create my own mapping application. Chapter 9 describes a simple dataset of five restaurant locations added to a point layer, then queried using an input radius from a previously-clicked point. This is supposed to create a table of all locations(restaurants) within the radius.

This is Kropla's function which finds point locations within the radius. The arguments to NearbyStores() are point object, map object and radius value(miles) respectively:

function NearbyStores($point,$map,$radius) {
     // get query layer
     $qlayer = $map->getLayerByName('poi');
     $qlayer->set("tolerance",$radius);

     // query the query layer - $radius is set in browser
     // queryByPoint ignores TOLERANCE units using native map units
     // instead - in this case decimal degrees. The number of miles
     // per degree is (approximately of course) 69.04 therefore
     // the correction from degrees to miles. This would have to
     // change if TOLERANCEUNITS, the map or scale units change.

     @$qlayer->queryByPoint($point, MS_MULTIPLE, $radius/69.04);
     $numResults = $qlayer->getNumResults();

     // we've got results, store id equals shape index

     if ($numResults != 0) {
          for ($i = 0; $i < $numResults; $i++) {
              $query_result = $qlayer->getResult($i);
              $StoreList[$i] = $query_result->shapeindex;
          }
     } else {
          $StoreList = "";      // no results
     }
     return $StoreList;
}

The variable $numResults appears to correctly identify the number of locations within your input radius. But $query_result->shapeindex behaves strangely. The array $Storelist[], when populated with all five restaurant store-ids in the database using function NearbyStores(), should contain 1,2,3,4,5 (there is no store id 0). However if only 1 location is found, $Storelist[] contains 0, if 2 locations, it contains 0,1 and if all five are found it contains 0,1,1,1,1. In other words, the first array element of $Storelist becomes zero and any subsequent elements are always 1. Consequently when you proceed to populate the display table for all five, you get details of the first location followed by four duplicates of the second.

Is anyone familiar with Kropla's book, or can anyone explain this behaviour by the various PHP/Mapserver functions shown above or suggest a reasonable alternative?

Many Thanks,
Rob Pearce


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