[gdal-dev] Convert ESRI Shapefile to GeoJSON in memory, code in c#

[Christian Sörensen]

Hi,

I'm a bit out of my depth here trying out GDAL in c#. Please help. =)

My code works fine if I output the GeoJSON to a file on disk. But I would
really not prefer having to intermittently store the result on disk just to
read it back into memory again.

It seems like all methods exposed by SWIG in c# that have something to do
with reading virtual files back into a buffer is missing?

Where is VSIGetMemFileBuffer or VSIFReadL? Python seems to have  VSIFReadL,
but not C#.

I'm doing this wrong?

Below is my code.
















































































* private FeatureCollection ImportShapeFile(IEnumerable<ImportFile> files)
      {            var tempJsonFilename = $"/vsimem/temp.json";
GdalConfiguration.ConfigureGdal();
GdalConfiguration.ConfigureOgr();            try            {
  // Copy into GDAL                foreach (var file in files)
  {                    Gdal.FileFromMemBuffer($"/vsimem/{file.Filename}",
file.Data);                }                // Load shape
var shpDriver = Ogr.GetDriverByName("ESRI Shapefile");                var
shpFile = files.First(f => f.Filename.EndsWith(".shp"));                var
shpDatasource = Ogr.Open($"/vsimem/{shpFile.Filename}", 0);
if (shpDatasource == null)                    return null;
var shpLayer = shpDatasource.GetLayerByIndex(0);                // Setup
projection transform to WGS84                var srcProjection =
shpLayer.GetSpatialRef();                var destProjection = new
SpatialReference("");                destProjection.ImportFromEPSG(4326);
              var transform = new CoordinateTransformation(srcProjection,
destProjection);                // Copy layer to geo json
var jsonDriver = Ogr.GetDriverByName("GeoJSON");                var
jsonDataSource = jsonDriver.CreateDataSource(tempJsonFilename, new string[]
{ });                var jsonLayer =
jsonDataSource.CreateLayer(shpLayer.GetName(), destProjection,
shpLayer.GetGeomType(), new string[] { });                var shpFeature =
shpLayer.GetNextFeature();                while (shpFeature != null)
        {                    // Transform geometry                    var
geometry = shpFeature.GetGeometryRef();
geometry.Transform(transform);                    // Save feature to new
layer                    jsonLayer.CreateFeature(shpFeature);
      shpFeature = shpLayer.GetNextFeature();                }
  // TODO: HERE I would like to read the information from my tempJsonFile
back into a byte array, before unlinking.                var jsonBuffer =
new byte[0];                // Close all GDAL stuff
jsonLayer.Dispose();                jsonDataSource.Dispose();
  jsonDriver.Dispose();                shpLayer.Dispose();
shpDatasource.Dispose();                shpDriver.Dispose();
// Read json from buffer                var jsonText =
Encoding.UTF8.GetString(jsonBuffer, 0, jsonBuffer.Length); ;
var json = JsonConvert.DeserializeObject<FeatureCollection>(jsonText);
          return json;            }            catch (Exception exception)
          {                throw exception;            }
finally            {                // Clear files from GDAL
Gdal.Unlink(tempJsonFilename);                foreach (var file in files)
              {
Gdal.Unlink($"/vsimem/{file.Filename}");                }            }
  }*


Best Regards
Christian

-- 

*Christian Sörensen*
*UX Productions AB*
www.uxproductions.se | christian at uxproductions.se | +46 (0)70 26 77 212
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