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.