使用 dapper 查询空间数据

我找到了一些相关的问题 https://stackoverflow.com/questions/18088169/dapper-spatial-geography-type，但作者放弃了，继续使用存储过程来进行“映射”。

这实际上是一个延续问题here https://stackoverflow.com/questions/24402424/how-to-insert-dbgeography-to-sql-server-using-dapper

Model

public class Store
{
    public int Id { get; private set; }
    public string Name { get; set; }
    public string Address { get; set; }
    public DbGeography Location { get; set; }
}

Querying

using (SqlConnection conn = SqlHelper.GetOpenConnection())
{
    const string sql = "Select * from Stores";
    return conn.Query<Store>(sql, new { Tenant_Id = tenantId });
}

Dapper 不理解空间数据，正如许多人所说，支持供应商特定实现并不是作者的初衷。但扩展的文档Query<T>很难找到支持

我对此有一个探索here https://github.com/StackExchange/dapper-dot-net/commit/e26ee0abe5bdff561ff59fded87cabb9f5d983a1，以下测试通过：

class HazGeo
{
    public int Id { get;set; }
    public DbGeography Geo { get; set; }
}
public void DBGeography_SO24405645_SO24402424()
{
    global::Dapper.SqlMapper.AddTypeHandler(typeof(DbGeography), new GeographyMapper());
    connection.Execute("create table #Geo (id int, geo geography)");

    var obj = new HazGeo
    {
        Id = 1,
        Geo = DbGeography.LineFromText("LINESTRING(-122.360 47.656, -122.343 47.656 )", 4326)
    };
    connection.Execute("insert #Geo(id, geo) values (@Id, @Geo)", obj);
    var row = connection.Query<HazGeo>("select * from #Geo where id=1").SingleOrDefault();
    row.IsNotNull();
    row.Id.IsEqualTo(1);
    row.Geo.IsNotNull();
}

class GeographyMapper : Dapper.SqlMapper.TypeHandler<DbGeography>
{
    public override void SetValue(IDbDataParameter parameter, DbGeography value)
    {
        parameter.Value = value == null ? (object)DBNull.Value : (object)SqlGeography.Parse(value.AsText());
        ((SqlParameter)parameter).UdtTypeName = "GEOGRAPHY";
    }
    public override DbGeography Parse(object value)
    {
        return (value == null || value is DBNull) ? null : DbGeography.FromText(value.ToString());
    }
}

It looks可行，但我还没有在每个 i 上加点并在每个 t 上划线。欢迎您在本地尝试该提交 - 我希望得到反馈。