Dynamically set bounds on nearbySearch based on search critieria - google-maps-api-3

Question

We've implemented a search box and google maps on our page to allow customers to perform searches based on places queries, and so far it's working well. However, using TextSearch we almost always get 20 results (unless it's a specific point). What we prefer though, is to return a set of results that makes more sense to a user based on their search (i.e. if they're searching for churches within a zipcode, we shouldn't show churches outside the zip code).
I know we can bias our results based on location and radius, and even restrict results based on location / radius using NearbySearch.
However, our customers are national users who may be searching in any area in the world, so we're not sure, until the user searches, what location and radius to set as a restriction. I'd like to determine that dynamically based on their query.
For example, in Google Maps if you search for "Churches near 30319" you get a much more localized result set than "Churches near Georgia"
Churches near 30319:
https://maps.google.com/maps?q=churches+near+30319&hl=en&sll=33.772251,-84.296934&sspn=0.049158,0.082312&hq=churches&hnear=Atlanta,+Georgia+30319&t=m&z=14
Churches near Georgia:
https://maps.google.com/maps?q=churches+near+Georgia&hl=en&sll=33.870438,-84.332304&sspn=0.049102,0.082312&hq=churches&hnear=Georgia&t=m&z=8
I've tested doing a separate query using geocode to get the single-point location of the query. i.e.
getGeneralVicinity = ->
address = $('#address').val()
window.oneq.geocode.geocoder.geocode
address: address,
(results, status) ->
if status is google.maps.GeocoderStatus.OK
console.log(results[0].types)
It seems by possibly finding the type of the geocode result (i.e locality) we could determine a radius and use the geometry.location for the location bounds. Unfortunately, it's not consistent, and if a user only searches for "churches", this doesn't give us the desired results.
Any help would be greatly appreciated.

Answer 1

You almost had it. I will refer to the Geocoding API as its JSON feed rather than the Google implementation of it, so detail will come straight from the source. There are some very interesting parameters that come back when geocoding something. Try it:
Georgia: http://maps.googleapis.com/maps/api/geocode/json?address=georgia&sensor=true
30319:http://maps.googleapis.com/maps/api/geocode/json?address=30319&sensor=true
Both of the second-tier address components are Georgia. However, there are a few differing parameters, and the one you want is geometry. This indicates the shape of the area.
Take, for example, the 30319 request. You will get as bounds:
"bounds" : {
"northeast" : {
"lat" : 33.9203610,
"lng" : -84.30943599999999
},
"southwest" : {
"lat" : 33.83286890,
"lng" : -84.35826589999999
}
},
"location" : {
"lat" : 33.87309460,
"lng" : -84.33842899999999
},
This tells you three things:
The corners of the bounding box
The centre of the box (which will be the intersection of the vertex lines)
This allows you to compute the maximum distance from your centre, which you can then feed back into your google places API search as radius. Conversion from lat/long to distance is trivial: it's called the orthodromic path. Two formulas exist - one for small distances (Haversine's formula), the other for large distances (this). Someone wrote a calculator for these: http://williams.best.vwh.net/gccalc.htm . You'll quickly see that the bounding box for 30319 spans 10km, whilst the georgia one spans almost 700 (which would require multiple Google Places requests to match).
Let me know if this wasn't clear and I'll elaborate further.