wiki:BluePrint/GIS/ShapefileLayers

Version 22 (modified by Fran Boon, 8 years ago) ( diff )

Work on this has started

Shapefile Layers

Upload a Shapefile to display on the map.

Options:

We can include TM_WORLD_BORDERS-0.3.zip as a useful base/sample

Alternative options:

Imports

PaulPorthouse [2013-04-27 at the Hackathon]:

Our idea is to use a basic web form with a file upload (similar to the Import from OpenStreetMap) where you can select which ShapeFile to use. You should also be able to set basic information including database connection details. This will then upload the shape and use OGR2OGR to convert the ShapeFile to geometry and import it into the specified database.

A basic OGR2OGR which should accomplish the import is: OGR2OGR -overwrite -f "PostgreSQL" PG:dbname=databaseconnection shapefile.sh

This could be called directly from Python by running it as a sub process.

Alternatively, to use Python bindings, you could perform the import using GDAL which would allow more control over the import directly within Python, but should still handle the import into Postgres.

'''
Dump the contents of a shapefile to an lxml etree object
Assumes the shapefile is encoded in UTF-8 format
Tested with TM_WORLD_BORDERS-0.3.shp
'''
import sys
import ogr
import os

from lxml import etree

if len(sys.argv) != 2:
    print "Usage: importshape.py filename"
    sys.exit(0)
    
shapefilename = sys.argv[1]

layername = os.path.splitext(os.path.basename(shapefilename))[0]

#Create the datasource
ds = ogr.Open( shapefilename )

#Open the shapefile
if ds is None:
    print "Open failed.\n"
    sys.exit(0)
    
#Get the layer and iterate through the features
lyr = ds.GetLayer(0)

root = etree.Element("shapefile",name=layername)

for feat in lyr:
	
    featurenode = etree.SubElement(root,"feature")
    
    feat_defn = lyr.GetLayerDefn()
		
    for i in range(feat_defn.GetFieldCount()):
		
	field_defn = feat_defn.GetFieldDefn(i)
			
	fieldnode = etree.SubElement(featurenode,field_defn.GetName())
		
	if field_defn.GetType() == ogr.OFTInteger:
	    fieldnode.text = str(feat.GetFieldAsInteger(i))

	elif field_defn.GetType() == ogr.OFTReal:
	    fieldnode.text = str(feat.GetFieldAsDouble(i))

	elif field_defn.GetType() == ogr.OFTString:
	    FieldString = str(feat.GetFieldAsString(i))
	    fieldnode.text = FieldString.decode(encoding='UTF-8',errors='strict')
	    
    wktnode = etree.SubElement(featurenode,"wkt")
	
    geom = feat.GetGeometryRef()	
    wktnode.text = geom.ExportToWkt()    
		

#Test the etree object
xmlString = etree.tostring(root, pretty_print=True)
f = open("test.xml","w")
f.write(xmlString)


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