Columns and their types for shapefile in OGR/python

Question

I am trying to list all the columns (or features) and their types for a shapefile. shp2pgsql shows following schema:

CREATE TABLE "liberia" (gid serial,
"local_name" varchar(100),
"eng_name" varchar(100),
"cntry_name" varchar(75),
"type" varchar(75),
"cntry_code" varchar(10),
"continent" varchar(50),
"iso_code" varchar(10),
"volume" int4,
"id_7_1" varchar(100),
"id" numeric(10,0));
ALTER TABLE "liberia" ADD PRIMARY KEY (gid);
SELECT AddGeometryColumn('','liberia','geom','5578','MULTIPOLYGON',2);

The following code snippet tries to achieve that:

 from osgeo import ogr
 reader = ogr.Open("file.shp")
 x = reader.GetLayer(0)
 fields  = x.schema
 for l in ll:
    print l.GetName()
    print l.GetType()

Which prints output as follows:

LOCAL_NAME
4
ENG_NAME
4
CNTRY_NAME
4
...

I am facing two problems. One the geom column/feature is missing from the list and second deciphering type id to python or postgres type.

Answer 1

I will address the problems seperately:

Type of shapefile column

The schema function is actually a wrapper around the GetFieldDefn() and GetLayerDefn() functions:

output = [] 
defn = self.GetLayerDefn() 
for n in range(defn.GetFieldCount()): 
    output.append(defn.GetFieldDefn(n)) 
return output 

(source code)

The individual entries l you iterate over are therefore instances of OGRFieldDefn (Documentation). They have a function called GetFieldTypeName(Type) that you can use:

for l in ll:
    type = l.GetType()
    type_name = l.GetFieldTypeName(type)
    print type_name
    print l.GetName()

Accessing the geometry

You can iterate over the features in a shapefile as usual:

from osgeo import ogr
reader = ogr.Open("file.shp")
for feat in reader.GetLayer():
    geom = feat.GetGeometryRef()
    # geom is now an ogr geometry object
    print geom.ExportToWkt()