Hide menu Last updated: Oct 31 2016
Area: Episerver Find Applies to versions: 12 and higher
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Geo Search

Geo search is search based on geographical coordinates and distances. This topic describes how to find documents in relation to geographical location of a website visitor, when building search features with Episerver Find.

How it works

For the server to recognize that a pair of numbers are coordinates, the fields need to be mapped as a geo point. However, through conventions on the server side and in the .NET API, mapping is not needed as long as geographical locations are exposed as instances of the GeoLocation class. So, to use geo search functionality, indexed objects should have either a GeoLocation type property or a custom mapping, such as an extension method that returns a GeoLocation.

After objects with locations are indexed, you can filter on them using an expression that invokes the Within and WithinDistanceFrom extension methods.

Distance from location

Here we describe how to find documents within a certain distance from a location.

Assume the following class.

And you create and index three instances of it with locations in Stockholm.

The previous example shows three restaurants, one close to Sergels torg in the center of Stockholm, and two in another part of Stockholm, Sodermalm. You can find restaurants close to Sergels torg by searching for restaurant type and filtering out documents whose Location property is not within one kilometer of Sergels torg.

This produces a single result: the restaurant close to Sergels torg.

You can also search for documents within a specific range of a location.

Note: The use of the two extension methods Kilometer and Kilometers above. The WithinDistanceFrom method requires distances as either miles or kilometers, which is represented by the abstract GeoDistance type and its sub classes Kilometer and Miles. The extension methods above offer a convenient way to create instances of the Kilometer class, which is a sub-class of GeoDistance. Similar extension methods exist for miles.

Locations in an area

Using the Within method, you can search for documents within an area represented by at least three coordinates. For example, you have the following helper class with coordinates that describe Sodermalm in Stockholm (found using Google maps).

You can use the Within method to find restaurants in Sodermalm.

Sorting by geographical distance

To order search hits for GeoLocation fields by distance from a location, use the OrderBy and OrderByDescending methods. As an example, the following code orders search results by proximity to Sergels Torg in Stockholm.

Matching documents with no location are ordered last when using the OrderBy method, and first when using the OrderByDescending method.

Aggregations/facets

Apart from filtering and sorting by geographical coordinates/distance, you can also count how many documents/locations are within certain distances from a specific location using the GeoDistanceFacetFor method. See geographical distance facets.

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