[OpenLayers-Users] minifying geojson data

[Mr. Puneet Kishor]

Right now I am creating a vector layer with features that are clickable, and show a popup window with the feature's attributes. My code is like so on the server side where I am selecting (fictitious) "meetings" from a database

    while (meetings) {
        push @features, {
            type => "Feature",
            properties => {
                "long field1 name" => $field1, 
                "long field2 name" => $field2, 
                "long field3 name" => $field3
            },
            geometry => {
                type => "Point",
                coordinates => [$lng, $lat]
            }
        };
    }
    my %meetings = (
        meetings => {type => "FeatureCollection", features => \@features}
    );
    my $res = to_json \%meetings;

and then, in the browser

    // In my ajax call
    success: function(data) {
        var geojson_format = new OpenLayers.Format.GeoJSON();
        ..
        lyr.addFeatures(geojson_format.read(data["meetings"]));
        
        lyr.events.on({
            "featureselected": onFeatureSelect,
            "featureunselected": onFeatureUnselect
        });
    }
    
    
    function onFeatureSelect(evt) {
        var feature = evt.feature;
        var str = "";
        for (var i in feature.attributes) {
            str += "<b>" + i + ":</b> " + feature.attributes[i] + "<br />";
        }
        
        popup = new OpenLayers.Popup.FramedCloud(.. using str ..);
        ..
        map.addPopup(popup, true);
    };
    
This works great, but for a few thousand features, all those "long fields names" add up to a lot of wasteful data transfer. In the interest of reducing data transfer, I am hoping to implement a keymap for my attribute names (keys), and then send the keymap along with the new keys. Something like so on the server side (kinda like my own minification scheme) --

    while (meetings) {
        push @features, {
            type => "Feature",
            properties => {
                a => $field1, 
                b => $field2, 
                c => $field3
            },
            geometry => {
                type => "Point",
                coordinates => [$lng, $lat]
            }
        };
    }
    my %meetings = (
        keymap => {
            a => "long field1 name", 
            b => "long field2 name", 
            c => "long field3 name"
        },
        meetings => {type => "FeatureCollection", features => \@features}
    );
    my $res = to_json \%meetings;
    
But, I am at a loss as to how to modify my JavaScript code to use this keymap. `evt.feature` seems to have an "attributes" key that has been automatically mapped to the "properties" key sent from the server. How do I get the data.keymap to my onFeatureSelect(evt) callback?