Dynamic Select

Description

The default “Zoom To”s with GeoMOOSE are static and predefined in the Mapbook. They do not change based on updates of a layer, and can be tedious to type out even for layers with relatively few features. To address this, DynamicZoom provides an Ajax-capable feature look up that allows the user to select a dataset, then a feature from that dataset. After selecting the feature, the map zooms to the extent of that feature.

Adding to Application

To add Dynamic Select to your application add:

<script type="text/javascript" src="extensions/DynamicZoom.js"></script>

Configuration

Configuring Dynamic Select consists of three steps:

1. Create a template file.
2. Edit the layer’s metadata.
3. Add the layer to DynamicZoomConfiguration

1. Create the template file

To create the template file, goto the direct where the mapfile exists. For this example, we’ll be using the “counties_border” layer inside of the “basemap.map” mapfile. This mapfile can be found in the maps/demo/statedata directory that comes with the GeoMOOSE demo. The template is very simple, and creates the needed to create “<option>” tags in HTML:

<!-- MapServer Template -->
<option value="[shpext]">[COUNTYNAME]</option>

The first line is the MapServer “magic string” that is required for template files starting in version 5.4. The second line, has a few important prts. The first is the “[shpext]” directive, this tells mapserver to place the feature’s extent into this part of the string. “[COUNTYNAME]” tells MapServer to place the feature’s title, in this case ‘COUNTYNAME,’ into the template. When working with a different layer, substitute “COUNTYNAME” for whatever the layer’s title column name happens to be. For this example, we’ll name the file, “county_dynamic_zoom.html”

2. Edit the layer’s metadata.

Now we need to tell GeoMOOSE about this template file. The method for doing that is to add a METADATA entry to the mapfile. First, it is neccessary to find the LAYER entry in the mapfile, that will look something like this:

LAYER
        NAME county_borders
        ...
END

Then, check to see if there is already a METADATA section, if there is not then add one:

LAYER
        NAME county_borders
        ...
        METADATA
        END
END

Finally, the metadata entry needs to be made:

LAYER
        NAME county_borders
        ...
        METADATA
                'dynamic_zoom' 'county_dynamic_zoom.html'
        END
END

3. Add the layer to DynamicZoomConfiguration

Edit htdocs/extensions/DynamicZoom.js, at the very top is a Javascript Object named “DynamicZoomConfiguration.” In DynamicZoomConfiguration there is an entry called layers, it is an object that contains the information for the various layers. If the file is from a default-GeoMOOSE installation then the entry for “Counties” is already there. If it is missing then adding the following lines would create it:

...
layers: {
        'Counties' : {
                mapbook_src: 'borders/county_borders', /* this is the src of the layer in the mapbook */
                qitem: '', /* leave blank */
                string: '' /* leave blank */
        }
}
...

Other Options

In the above instructions “qitem” and “qstring” were intentionally left blank. However, if they are set, they will act as a filter on the dataset. This is useful if you have multiple feature types stored in a single table. By default, the filtering is case-insensitive.