OGR interface in GRASS 7

See also ​examples from GRASS ​User Wiki.

Direct OGR read access

Capability to read OGR layers directly without linking them via v.external. Example:

v.info map=~/shapefiles/@OGR layer=busstopsall
v.extract input=PG:dbname=nc_spm_08@OGR layer=busstopsall where="STREET_1 = 'William Moore Dr.'" output=b1

List of modules which supports direct OGR read access ((*) indicates work in progress):

• v.info (r39161), v.db.connect (r39538), v.extract (r39621), v.db.select (r39556), v.buffer (r39809), v.category (r39812), v.class (r39813), v.clean (r39814), v.delaunay (r39821), v.dissolve (r39822), v.distance (r39823), v.drape (r39826), v.extrude (r39827), v.generalize (r39828), v.hull (r39829), v.kcv (r39832), v.neighbors (r39834), v.normal (r39839), v.out.ascii (r39881), v.out.dxf (r39882), v.out.ogr (r39883), v.out.pov (r39884), v.out.svg (r39885), v.overlay (r39895), v.parallel (r39896), v.pertrub (r39897), v.qcount (r39898), v.report (r39905), v.sample (r39906), v.segment (r39907), v.reclass (r39908), v.random (r39909), v.rast.stats (r39910), v.select, v.split, v.surf.idw, v.surf.rst, v.to.3d, v.to.db, v.to.points, v.to.rast, v.to.rast3, v.transform, v.type, v.univar, v.what (r40188)

Direct OGR write access

Capability to write OGR layers directly without need to store data in the native GRASS vector format and then exporting data using v.out.ogr.

Testcase:

• location: nc_spm_08
• Shapefile directory: ~/ncshape
• PostGIS database: pgis_nc

Scenario 1

Use parameters output for output OGR datasource and olayer for OGR layer. Example:

# input: GRASS data
# output: PostGIS database
v.extract map=obce where="NAZEV = Solany" output=PG:dbname=gisdb@OGR olayer=obce

# input: PostGIS layer, ESRI Shapefile
# output: PostGIS database
v.select ainput=PG:dbname=gisdb@OGR alayer=zeleznice \
 binput=shps@OGR blayer=obce operator=intersects \
 output=PG:dbname=gisdb@OGR olayer=obce_zelez

Status: not planned to be implemented

Scenario 2

Use v.external.out

# input: GRASS data
# output: PostGIS database
v.external.out dsn=PG:dbname=pgis_nc format=PostgreSQL
v.extract input=bridges where="BRIDGE_NUM=417" output=bridges_417

# input: PostGIS layer, ESRI Shapefile
# output: PostGIS database
v.select ainput=PG:dbname=gisdb@OGR alayer=zeleznice \
 binput=shps@OGR blayer=obce operator=intersects \
 output=obce_zelez

Status: implemented grass/trunk/vector/v.external.out

Tasks

• Attribute table (write) access for OGR-linked vectors (direct or linked by v.external)
  • Implemented in r47225

Changes in vector library

• write_ogr.c​

List of updated modules

List of modules which supports direct OGR write access:

• v.edit
• v.extract
• v.select

Related OGR tickets

• ​#4202
• ​#4217