Reverse Geocoding With Dynamic Form - api

Question

I've been trying to find a way to use the 'Reverse Geocoding' service with the Latitude and Longitude co-ordinates coming from two text boxes on my HTML form, and I must admit I'm not really sure what I need to do.
I have managed to do this with the 'Geocode' service (see code below), but I just wondered whether someone may be able to point me in the right direction of how I could adapt the 'Geocode' javascript I have to the 'Reverse Geocoging' service.
(function Geocode() {
// This is defining the global variables
var map, geocoder, myMarker;
window.onload = function() {
//This is creating the map with the desired options
var myOptions = {
zoom: 5,
center: new google.maps.LatLng(55.378051,-3.435973),
mapTypeId: google.maps.MapTypeId.ROADMAP,
mapTypeControl: true,
mapTypeControlOptions: {
style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
position: google.maps.ControlPosition.BOTTOM
},
navigationControl: true,
navigationControlOptions: {
style: google.maps.NavigationControlStyle.ZOOM_PAN,
position: google.maps.ControlPosition.TOP_RIGHT
},
scaleControl: true,
scaleControlOptions: {
position: google.maps.ControlPosition.BOTTOM_LEFT
}
};
map = new google.maps.Map(document.getElementById('map'), myOptions);
// This is making the link with the 'Search For Location' HTML form
var form = document.getElementById('SearchForLocationForm');
// This is catching the forms submit event
form.onsubmit = function() {
// This is getting the Address from the HTML forms 'Address' text box
var address = document.getElementById('GeocodeAddress').value;
// This is making the Geocoder call
getCoordinates(address);
// This is preventing the form from doing a page submit
return false;
}
}
// This creates the function that will return the coordinates for the address
function getCoordinates(address) {
// This checks to see if there is already a geocoded object. If not, it creates one
if(!geocoder) {
geocoder = new google.maps.Geocoder();
}
// This is creating a GeocoderRequest object
var geocoderRequest = {
address: address
}
// This is making the Geocode request
geocoder.geocode(geocoderRequest, function(results, status) {
// This checks to see if the Status is 'OK 'before proceeding
if (status == google.maps.GeocoderStatus.OK) {
// This centres the map on the returned location
map.setCenter(results[0].geometry.location);
// This creates a new marker and adds it to the map
var myMarker = new google.maps.Marker({
map: map,
zoom: 12,
position: results[0].geometry.location,
draggable:true
});
//This fills out the 'Latitude' and 'Longitude' text boxes on the HTML form
document.getElementById('Latitude').value= results[0].geometry.location.lat();
document.getElementById('Longitude').value= results[0].geometry.location.lng();
//This allows the marker to be draggable and tells the 'Latitude' and 'Longitude' text boxes on the HTML form to update with the new co-ordinates as the marker is dragged
google.maps.event.addListener(
myMarker,
'dragend',
function() {
document.getElementById('Latitude').value = myMarker.position.lat();
document.getElementById('Longitude').value = myMarker.position.lng();
var point = myMarker.getPosition();
map.panTo(point);
}
);
}
}
)
}
})();
UPDATE
Firstly, many thanks for the code you kindly posted and the suggestion to go and have a look at the Google documentation.
From what you suggested, and from what I took from the additional documentation I came up with the following. However, when I click my submit button nothing happens, almost as if there is no command attached to it. I don't receive any error messages and I've checked to make sure that I've linked the code to the correct fieldnames and all seems ok. I just wondered whether it would be at all possible if you, or indeed anyone else, could take a look at it please to tell me where I've gone wrong.
Many thanks and kind regards
(function ReverseGeocode() {
var form, geocoderRequest, latlng, myMarker, point;
window.onload = function() {
//This is creating the map with the desired options
var myOptions = {
zoom: 5,
center: new google.maps.LatLng(55.378051,-3.435973),
mapTypeId: google.maps.MapTypeId.ROADMAP,
mapTypeControl: true,
mapTypeControlOptions: {
style: google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
position: google.maps.ControlPosition.BOTTOM
},
navigationControl: true,
navigationControlOptions: {
style: google.maps.NavigationControlStyle.ZOOM_PAN,
position: google.maps.ControlPosition.TOP_RIGHT
},
scaleControl: true,
scaleControlOptions: {
position: google.maps.ControlPosition.BOTTOM_LEFT
}
};
map = new google.maps.Map(document.getElementById('map'), myOptions);
var latlng = new google.maps.LatLng('Latitude', 'Longitude');
// This is making the Geocode request
geocoder.geocode({'LatLng': latlng}, function(results, status) {
if (status == google.maps.GeocoderStatus.OK) {
if (results[1]) {
map.setZoom(11);
var myMarker = new google.maps.Marker({
position: results[0].geometry.location,
map: map
});
//This fills out the 'Address' text boxe on the HTML form
document.getElementById('Address').value= results[0].geometry.location.latlng();
var point = myMarker.getPosition();
map.panTo(point);
}
}
}
)}})

Answer 1

Once you have the latitude and longitude from your form, you do something like this (using your above code as a starting point, for the sake of clarity):
var latlng = new google.maps.LatLng(latitudeFromForm,longitudeFromForm);
// This is creating a GeocoderRequest object
var geocoderRequest = {
'latlng':latlng
}
// This is making the Geocode request
geocoder.geocode(geocoderRequest, function(results, status) {
// This checks to see if the Status is 'OK 'before proceeding
if (status == google.maps.GeocoderStatus.OK) {
// Do stuff with the result here
}
If you haven't read it yet, you may want to read the Reverse Geocoding section of http://code.google.com/apis/maps/documentation/javascript/services.html#ReverseGeocoding.