[OpenLayers-Users] Re: Iterating through features in a vector layer?

[Robert Sanson]

THis appears to be due to a synchronisation issue between OpenLayers and a Ext.grid.GridPanel loaded with a GeoExt.data.FeatureStore tied to the vector layer. I am looking for a way to force an update to the GridPanel when an attribute was modified, and was using:

cropStore.unbind(); 
cropStore.bind(crops); 

but this seems to be causing the features to b re-added to the layer, resulting in a doubling.

Can anyone suggest how to get GeoExt to re-read the features so the GridPanel is updated with the new attributes?

Many thanks,

Robert 

>>> Robert Sanson 24/01/2012 2:29 p.m. >>>
I am using OpenLayers v2.11, and have a vector layer loaded from  geometry in WKT format separated from attributes using pipe delimited text from a database (via a Python cgi-bin script).

I am trying to write a function that iterates through all of the features and then POST updates back to the database when certain conditions are met.
 My difficulty is that layer.features.length is returning double the number of features.

Here is my code that creates the layer and loads the features:

function setHTML4cr(response4) {
	var cropnum = 0;
    var lines, line;
    var cropid, name, crds;
    var cropgeom;
    if (response4.responseText.toUpperCase().indexOf('ERROR') != -1) {
      alert(response4.responseText);
    }
    else {
      crops = new OpenLayers.Layer.Vector("Crops",
                  {isBaseLayer: false,
                   styleMap: crop_style,
                   rendererOptions: {zIndexing: true},
                   extractAttributes: true });
      var lines = response4.responseText.split('\n');
      for ( var i=0;i<lines.length;i++) {
        line = lines[i].split("|");
        if ( line.length == 3 ) {
          cropid = line[0];
          name = line[1];
          crds = line[2];
          cropgeom = wkt_format.read(crds);
          cropgeom.attributes.id = cropid;
          cropgeom.attributes.name = name;
          cropgeom.attributes.pstate = "pre";
          crops.addFeatures(cropgeom);
		cropnum = cropnum + 1;
        }
      }
      map.addLayer(crops);
      alert("Crops layer loaded and ready for digitising with " + cropnum + " features!");
}

This is reporting the correct number of features, and the features are drawn on the map.

However, this function is reporting double the number of features:

function savecrop() {
	var f;
    alert(crops.features.length);
	 var allf = [];
    for (i = 0; i < crops.features.length; i++) {
	f = crops.features[i];
	allf.push(f.attributes.id + "|" + f.attributes.name + "|" + f.attributes.pstate + "|" + f.state);
    }
    alert(allf.join("\n"));
}

Many thanks,

Robert





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