firstly you will need to find the geocordinates of your zip code (long/lat) you will probably need to make an api call to some external source to do this (google perhaps)

once you have the long/latitude you can use sql to find the distance between locations like below

SELECT  (geography::Point({referenceLocation.Longitude},{referenceLocation.Latitude},4326)).STDistance(geography::Point(otherlocation.Longitude, otherlocation.Latitude,4326)) as distance

You can also do it using the System.Data.Spatial.DbGeography library, but I had issues with that on my server, so used sql instead as it was pretty quick at calculating the distances.

Whatever you do it won't be that quick :) If at all possible, you would be better of storing the long/latitude along with your zip codes so you don't need to get them for your search.

no, that is how to get the distance between two points.

There is no simple concept of find me the nearest location. You will need to use some sort of api (googlemaps etc) and quite a bit of code to accomplish it.

I'm assuming you wish to do something similar to this I have a table of locations, on the form you can enter a postcode and distance and it returns all the locations within that distance.

as I said, you will need to use something to convert your zip code into a latitude/longitude pair before you can do anything.

Huw is on the money here.

Imagine you have three postcodes.

• M1 1AA - Manchester
• SK1 1AA - Stockport
• N1 1AA - North London

Now - I know that Stockport borders Manchester so I know that I want a search in Greater Manchester to return the first two but not North London. You have to think how can an algorithm do this?

The only real answer is to get Latitude and Longitude for the post codes (either get the editor to enter them or look them up from Google Maps / Open Street Maps etc?) and then do a geospatial search.

There might be something you could do with Zip codes to look for the first x digits but UK postcodes are based around the sorting offices NOT on towns / cities / counties. I can't speak for other countries postal codes but I'd imagine similar challenges.

Does that help you?

There are also several ways to do that, I am using simple SQL queries to return the distance between two points, that was the code I posted earlier.

However I decided to store my location data (lat + long in a custome table rather than as content because it made it simpler to query the distance data (I just added the id of the content item to link it's longitude and latitude record.

You can then simple do the following to get all records within X miles

public static Dictionary<Guid, double> FindNearestTo(GeoCoordinate referenceLocation)
{
    var locations= new Dictionary<Guid, double>();
    var sql = $@"
    SELECT  ic.LocationId, (geography::Point({referenceLocation.Longitude},{referenceLocation.Latitude},4326)).STDistance(geography::Point(ic.Longitude, ic.Latitude,4326)) as distance 
    from LocationCache ic 
    WHERE (geography::Point({referenceLocation.Longitude},{referenceLocation.Latitude},4326)).STDistance(geography::Point(ic.Longitude, ic.Latitude,4326)) < 16044
    WHERE distance < X";

    using (var scope = Current.ScopeProvider.CreateScope(autoComplete: true))
    {
        var database = scope.Database;
        locations= database.Dictionary<Guid, double>(sql);

    }

    return locations;
}

referenceLocation is the long/latitutude gepoint object for the postcode that the search enters, ic.LocationId is the guid for an umbraco content item(the location)

there is also a .Net spatial library (that is also tied to sql however) and although worked great on my dev machine errored on the server which is why I switched to a sql query.

There may be other libraries available, i didn't really look myself. I also do not store my location

Sorry, just about everything you guys are showing to help me (and I thank you for the attempts!) is throwing errors I can't figure out how to fix. There must be something in my site setup that's missing, but I don't know what it is. I'm creating totally new files to test the code rather than trying to adapt to what I have, but it's still not working.

what sort of error are you getting?

If you post some of the errors we may be able to point you in the right direction.

Glad you got it sorted! I can vouch from experience that it can handle ~500 locations without noticeable latency.

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