c# - 使用 Dapper 调用带有地理参数的 PostgreSQL 函数时出现 NotSupportedException

Question

我正在使用 Dapper(使用带有 NetTopologySuite 插件的 npgsql 数据提供程序)调用带有 geography 参数的 PostgreSQL 函数，然后收到一个 NotSupportedException:

System.NotSupportedException: The member _location of type NetTopologySuite.Geometries.Point cannot be used as a parameter value
at Dapper.SqlMapper.LookupDbType(Type type, String name, Boolean demand, ITypeHandler& handler) in C:\projects\dapper\Dapper\SqlMapper.cs:line 417
at Dapper.SqlMapper.CreateParamInfoGenerator(Identity identity, Boolean checkForDuplicates, Boolean removeUnused, IList`1 literals) in C:\projects\dapper\Dapper\SqlMapper.cs:line 2516
at Dapper.SqlMapper.GetCacheInfo(Identity identity, Object exampleParameters, Boolean addToCache) in C:\projects\dapper\Dapper\SqlMapper.cs:line 1707
at Dapper.SqlMapper.ExecuteScalarImplAsync[T](IDbConnection cnn, CommandDefinition command) in C:\projects\dapper\Dapper\SqlMapper.Async.cs:line 1207
...

但是当我使用 NpgsqlCommand 并通过 AddWithValue 方法指定类型时它工作正常。

如何让 Dapper 将 NetTopologySuite.Geometries.Point 映射到 geography？

Answer 1

搜索后我找到了一个 unaccepted answer这解决了我的问题。

确保我添加了 Npgsql.NetTopologySuite包及其映射器已启用 connection.TypeMapper.UseNetTopologySuite(); 然后 ADO.Net 命令工作正常。

我添加了一个自定义 Dapper.SqlMapper.TypeHandler:

public class GeographyTypeMapper : SqlMapper.TypeHandler<Geometry> {
    public override void SetValue(IDbDataParameter parameter, Geometry value) {
        if (parameter is NpgsqlParameter npgsqlParameter) {
            npgsqlParameter.NpgsqlDbType = NpgsqlDbType.Geography;
            npgsqlParameter.NpgsqlValue = value;
        } else {
            throw new ArgumentException();
        }
    }

    public override Geometry Parse(object value) {
        if (value is Geometry geometry) {
            return geometry;
        } 

        throw new ArgumentException();
    }
}

然后使用它 SqlMapper.AddTypeHandler(new GeographyTypeMapper()); 一切正常。