/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/postgisdb.py
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revision 1656 by bh, Mon Aug 25 18:26:54 2003 UTC revision 1662 by bh, Wed Aug 27 13:51:01 2003 UTC
# Line 180  class PostGISTable: Line 180  class PostGISTable:
180          """Return the name of the table in the database"""          """Return the name of the table in the database"""
181          return self.tablename          return self.tablename
182    
183        def Title(self):
184            """Return the title of the table.
185    
186            The title is currently fixed and equal to the tablename
187            """
188            return self.tablename
189    
190      def Dependencies(self):      def Dependencies(self):
191          """Return an empty tuple because a PostGISTable depends on nothing else          """Return an empty tuple because a PostGISTable depends on nothing else
192          """          """
# Line 202  class PostGISTable: Line 209  class PostGISTable:
209          cursor.execute("SELECT count(*) FROM %s" % self.tablename)          cursor.execute("SELECT count(*) FROM %s" % self.tablename)
210          return cursor.fetchone()[0]          return cursor.fetchone()[0]
211    
212      def ReadRowAsDict(self, row):      def RowIdToOrdinal(self, gid):
213            """Return the row ordinal given its id"""
214            cursor = self.db.cursor()
215            cursor.execute("SELECT count(*) FROM %s WHERE gid < %d;"
216                           % (self.tablename, gid))
217            return cursor.fetchone()[0]
218    
219        def RowOrdinalToId(self, num):
220            """Return the rowid for given its ordinal"""
221            cursor = self.db.cursor()
222            cursor.execute("SELECT gid FROM %s LIMIT 1 OFFSET %d;"
223                           % (self.tablename, num))
224            return cursor.fetchone()[0]
225    
226        def ReadRowAsDict(self, row, row_is_ordinal = 0):
227          cursor = self.db.cursor()          cursor = self.db.cursor()
228          cursor.execute(self.query_stmt + " LIMIT 1 OFFSET %d" % row)          if row_is_ordinal:
229                stmt = self.query_stmt + " LIMIT 1 OFFSET %d" % row
230            else:
231                stmt = self.query_stmt + " WHERE gid = %d" % row
232            cursor.execute(stmt)
233          result = {}          result = {}
234          for col, value in zip(self.columns, cursor.fetchone()):          for col, value in zip(self.columns, cursor.fetchone()):
235              result[col.name] = value              result[col.name] = value
236          return result          return result
237    
238      def ReadValue(self, row, col):      def ReadValue(self, row, col, row_is_ordinal = 0):
239          cursor = self.db.cursor()          cursor = self.db.cursor()
240          cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d" %          if row_is_ordinal:
241                         (self.column_map[col].name, self.tablename, row))              stmt = ("SELECT %s FROM %s LIMIT 1 OFFSET %d" %
242                        (self.column_map[col].name, self.tablename, row))
243            else:
244                stmt = ("SELECT %s FROM %s WHERE gid = %d" %
245                        (self.column_map[col].name, self.tablename, row))
246            cursor.execute(stmt)
247          return cursor.fetchone()[0]          return cursor.fetchone()[0]
248    
249      def ValueRange(self, col):      def ValueRange(self, col):
# Line 333  class PostGISShapeStore(PostGISTable): Line 363  class PostGISShapeStore(PostGISTable):
363          y=[]          y=[]
364          cursor = self.db.cursor()          cursor = self.db.cursor()
365          try:          try:
366              stmt = ("SELECT AsText(Envelope(%s)) FROM %s;"              # Using the extent function is postgis specific. An OGC
367                      % (self.geometry_column, self.tablename))              # Simple Features compliant solution would be to use a query
368              cursor.execute(stmt)              # like "SELECT AsText(Envelope(the_geom)) FROM mytable;" and
369                # calculate the bounding box by hand from that
370                cursor.execute("SELECT extent(%s) FROM %s;"
371                               % (self.geometry_column, self.tablename))
372              result = cursor.fetchone()              result = cursor.fetchone()
373              while result:              if result:
374                  result = result[0]                  (minx, miny), (maxx, maxy) \
375                  # Here we must do some parsing through the result string                        = wellknowntext.parse_wkt_thuban(result[0])[0]
376                  # to get the points out of the polygon which representes                  return (minx, miny, maxx, maxy)
                 # the bounding box The first and the last point of a  
                 # polygon are identical  
                 result = result.split("(")[2]  
                 result = result.split(")")[0]  
                 points = result.split(",")  
                 del points[4] # Remove the last point  
                 for point in points:  
                     px, py = point.split()  
                     x.append(float(px))  
                     y.append(float(py))  
                 result = cursor.fetchone()  
377          finally:          finally:
378              cursor.close()              cursor.close()
         if not x:  
             # Empty table  
             return None  
         return (min(x), min(y), max(x), max(y))  
379    
380      def Shape(self, shapeid):      def Shape(self, shapeid):
381          cursor = self.db.cursor()          cursor = self.db.cursor()
# Line 367  class PostGISShapeStore(PostGISTable): Line 385  class PostGISShapeStore(PostGISTable):
385          cursor.close()          cursor.close()
386          return PostGISShape(shapeid, wkt)          return PostGISShape(shapeid, wkt)
387    
388        def AllShapes(self):
389            cursor = self.db.cursor()
390            cursor.execute("SELECT gid, AsText(%s) FROM %s ORDER BY gid"
391                           % (self.geometry_column, self.tablename))
392            while 1:
393                result = cursor.fetchone()
394                if result is None:
395                    return
396                yield PostGISShape(result[0], result[1])
397    
398    
399      def ShapesInRegion(self, bbox):      def ShapesInRegion(self, bbox):
400          """Generate all shapes overlapping the region given by bbox."""          """Generate all shapes overlapping the region given by bbox."""
401          # IMPORTANT:This will work for PostGIS < 0.8          # IMPORTANT:This will work for PostGIS < 0.8
# Line 382  class PostGISShapeStore(PostGISTable): Line 411  class PostGISShapeStore(PostGISTable):
411          while 1:          while 1:
412              result = cursor.fetchone()              result = cursor.fetchone()
413              if result is None:              if result is None:
414                  raise StopIteration                  return
415              yield PostGISShape(result[0], result[1])              yield PostGISShape(result[0], result[1])
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