This GitHub Gist contains code snippets for implementing a feature in an ASP.NET Core Web API to find items within a specified radius using Entity Framework Core for database interaction.

gistfile1.cs

private double HaversineDistance(Coordinates point1, Coordinates point2)
{
    const double EarthRadiusKm = 6371;
    var dLat = Math.PI * ((double)point2.Latitude - (double)point1.Latitude) / 180.0;
    var dLon = Math.PI * ((double)point2.Longitude - (double)point1.Longitude) / 180.0;

    var a = Math.Sin(dLat / 2) * Math.Sin(dLat / 2) +
            Math.Cos(Math.PI * (double)point1.Latitude / 180.0) * Math.Cos(Math.PI * (double)point2.Latitude / 180.0) *
            Math.Sin(dLon / 2) * Math.Sin(dLon / 2);

    var c = 2 * Math.Atan2(Math.Sqrt(a), Math.Sqrt(1 - a));
    var distance = EarthRadiusKm * c;

    return distance;
}