PostGIS - Làm việc với các lớp GIS trong cơ sở dữ liệu PostgreSQL bằng C#

PostgreSQL (phần mở rộng PostGIS) là một trong những cơ sở dữ liệu được sử dụng rộng rãi nhất trong số các Phần mềm GIS. Aspose.GIS cho phép bạn làm việc với cơ sở dữ liệu PostgreSQL.

Lặp qua các lớp trong cơ sở dữ liệu PostGis

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
// First, we create the connection to the PostgreSQL with Npgsql library (https://www.nuget.org/packages/Npgsql/)
// Then, we pass this connection to Dataset.Open method in order to access tables in the PostgreSQL.
using (var connection = new NpgsqlConnection(postgreSqlConnectionString))
{
    connection.Open();
    using (var ds = Dataset.Open(connection, Drivers.PostGis))
    {
        // Only spatial tables are exported as layers, so the following code will list all tables
        // that have geometry column.
        for (int i = 0; i < ds.LayersCount; ++i)
        {
            Console.WriteLine(ds.GetLayerName(i));
        }
    }
}

Thêm một lớp mới trong cơ sở dữ liệu PostGis

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
// First, we create the connection to the PostgreSQL with Npgsql library (https://www.nuget.org/packages/Npgsql/)
using (var connection = new NpgsqlConnection(postgreSqlConnectionString))
{
    connection.Open();
    // Then, we pass this connection to Dataset.Open method in order to access tables in the PostgreSQL.
    using (var ds = Dataset.Open(connection, Drivers.PostGis))
    {
        // create table with the name "features_table" and fill it with data.
        using (var layer = ds.CreateLayer("features_table"))
        {
            layer.Attributes.Add(new FeatureAttribute("name", AttributeDataType.String) { Width = 50 });

            var feature = layer.ConstructFeature();
            feature.SetValue("name", "Name1");
            feature.Geometry = Geometry.FromText("POINT (10 20 30)");
            layer.Add(feature);

            feature = layer.ConstructFeature();
            feature.SetValue("name", "Name2");
            feature.Geometry = Geometry.FromText("POINT (-10 -20 -30)");
            layer.Add(feature);
        }
    }
}

Xuất một lớp từ cơ sở dữ liệu PostGis sang định dạng tệp

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
var outputPath = Path.Combine(RunExamples.GetDataDir(), "postgres_out.shp");

// First, we create the connection to the PostgreSQL with Npgsql library (https://www.nuget.org/packages/Npgsql/)
// Then, we pass this connection to Dataset.Open method in order to access tables in the PostgreSQL.
using (var connection = new NpgsqlConnection(postgreSqlConnectionString))
{
    connection.Open();
    using (var ds = Dataset.Open(connection, Drivers.PostGis))
    {
        // open table with the name "features_table" in Postgres database and save it to the shapefile.
        using (var table = ds.OpenLayer("features_table"))
        {
            table.SaveTo(outputPath, Drivers.Shapefile);
        }
    }
}