Dapper/Dapper.EntityFramework/DbGeographyHandler.cs

using Microsoft.SqlServer.Types;
using System;
using System.Data;
using System.Data.Entity.Spatial;
using System.Data.SqlClient;
using System.Data.SqlTypes;

namespace Dapper.EntityFramework
{
    /// <summary>
    /// Type-handler for the DbGeography spatial type.
    /// </summary>
    public class DbGeographyHandler : SqlMapper.TypeHandler<DbGeography>
    {
        /// <summary>
        /// Create a new handler instance.
        /// </summary>
        protected DbGeographyHandler() { /* create new */ }

        /// <summary>
        /// Default handler instance
        /// </summary>
        public static readonly DbGeographyHandler Default = new DbGeographyHandler();

        /// <summary>
        /// Assign the value of a parameter before a command executes.
        /// </summary>
        /// <param name="parameter">The parameter to configure.</param>
        /// <param name="value">Parameter value.</param>
        public override void SetValue(IDbDataParameter parameter, DbGeography? value)
        {
            object? parsed = null;
            if (value is not null)
            {
                parsed = SqlGeography.STGeomFromWKB(new SqlBytes(value.AsBinary()), value.CoordinateSystemId);
            }
            parameter.Value = parsed ?? DBNull.Value;
            if (parameter is SqlParameter sqlParameter)
            {
                sqlParameter.UdtTypeName = "geography";
            }
        }

        /// <summary>
        /// Parse a database value back to a typed value.
        /// </summary>
        /// <param name="value">The value from the database.</param>
        /// <returns>The typed value.</returns>
        public override DbGeography? Parse(object? value)
        {
            if (value is null || value is DBNull) return null;
            if (value is SqlGeography geo)
            {
                return DbGeography.FromBinary(geo.STAsBinary().Value, geo.STSrid.Value);
            }
            return DbGeography.FromText(value.ToString());
        }
    }
}