Generate zip code based on City and State with Google API - php

Question

Would there be a way to do a zip code lookup based on City/State input in a form? I'm thinking the Google geocode API might be the right direction. Any thoughts? I have a site built on Wordpress so the code would have to utilize PHP. Thanks in advance.

Answer 1

YQL can do things like this:
select name from geo.places.children where parent_woeid in (select woeid from geo.places where text="sunnyvale, usa" limit 1) AND placetype = 11
returns:
{
"query": {
"count": 6,
"created": "2011-03-16T06:49:09Z",
"lang": "en-US",
"results": {
"place": [
{
"name": "94086"
},
{
"name": "94087"
},
{
"name": "94088"
},
{
"name": "94089"
},
{
"name": "94090"
},
{
"name": "94085"
}
]
}
}
}
YQL Console
There are examples on there on how to implement queries like this in both PHP and Javascript on their site.

Answer 2

Geocoding is where you find the coordinates of an address. Yes you could geocode a city,state but this would give you he center of the city (as defined by the geocoder's internal database - typically a centroid or 'city hall'.
Most cities have multiple zip codes: Do you want all of these?
Similarly a zip code could contain multiple cities - especially in rural areas where zip codes can be large and cities are what other countries would call 'villages' and 'hamlets'
So you best bet is probably to get a database. There might be some free ones around (Geonames comes to mind but I don't think it has zip codes), but you might end up having to buy one.

Answer 3

First a note on the Google API: be aware of Google's TOS so you don't take a wasted path as others have done (sometimes unknowingly). Specifically: "Note: the Geocoding API may only be used in conjunction with a Google map; geocoding results without displaying them on a map is prohibited.".
Your best bet is to get a free zip code database if your project is not mission-critical; otherwise, you'll probably need a good commercial-grade database. Just google "commercial grade zip code database".
Also, see a good stack-overflow thread about this topic.