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CrsMapExtensions.cs
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51 lines (43 loc) · 1.67 KB
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using System;
using System.Threading.Tasks;
using Npgsql.GeoJSON.Internal;
namespace Npgsql.GeoJSON;
/// <summary>
/// Extensions for getting a CrsMap from a database.
/// </summary>
public static class CrsMapExtensions
{
/// <summary>
/// Gets the full crs details from the database.
/// </summary>
/// <param name="dataSource"></param>
public static async Task<CrsMap> GetCrsMapAsync(this NpgsqlDataSource dataSource)
{
var builder = new CrsMapBuilder();
using var cmd = GetCsrCommand(dataSource);
using var reader = await cmd.ExecuteReaderAsync().ConfigureAwait(false);
while (await reader.ReadAsync().ConfigureAwait(false))
builder.Add(new CrsMapEntry(reader.GetInt32(0), reader.GetInt32(1), reader.GetString(2)));
return builder.Build();
}
/// <summary>
/// Gets the full crs details from the database.
/// </summary>
/// <param name="dataSource"></param>
public static CrsMap GetCrsMap(this NpgsqlDataSource dataSource)
{
var builder = new CrsMapBuilder();
using var cmd = GetCsrCommand(dataSource);
using var reader = cmd.ExecuteReader();
while (reader.Read())
builder.Add(new CrsMapEntry(reader.GetInt32(0), reader.GetInt32(1), reader.GetString(2)));
return builder.Build();
}
static NpgsqlCommand GetCsrCommand(NpgsqlDataSource dataSource)
=> dataSource.CreateCommand("""
SELECT min(srid), max(srid), auth_name
FROM(SELECT srid, auth_name, srid - rank() OVER(PARTITION BY auth_name ORDER BY srid) AS range FROM spatial_ref_sys) AS s
GROUP BY range, auth_name
ORDER BY 1;
""");
}