/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/postgisdb.py
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revision 2057 by bh, Tue Feb 10 15:51:57 2004 UTC revision 2106 by bh, Fri Mar 12 12:59:33 2004 UTC
# Line 32  def psycopg_version(): Line 32  def psycopg_version():
32      return psycopg.__version__      return psycopg.__version__
33    
34  if psycopg is not None:  if psycopg is not None:
35        # type_map maps psycopg type objects.  It's a list of pairs since
36        # the psycopg type objects are unhashable.
37      type_map = [(psycopg.STRING, table.FIELDTYPE_STRING),      type_map = [(psycopg.STRING, table.FIELDTYPE_STRING),
38                  (psycopg.INTEGER, table.FIELDTYPE_INT),                  (psycopg.INTEGER, table.FIELDTYPE_INT),
39                    (psycopg.ROWID, table.FIELDTYPE_INT),
40                  (psycopg.FLOAT, table.FIELDTYPE_DOUBLE)]                  (psycopg.FLOAT, table.FIELDTYPE_DOUBLE)]
41    
42        # _raw_type_map maps the postgresql type constants to Thuban type
43        # constants.  This is very low level and postgresql specific and
44        # should be used only when necessary.
45        _raw_type_map = {}
46        def _fill_raw_type_map():
47            for psycopg_type, thuban_type in type_map:
48                for value in psycopg_type.values:
49                    _raw_type_map[value] = thuban_type
50        _fill_raw_type_map()
51    
52    
53  def quote_identifier(ident):  def quote_identifier(ident):
54      """Return a quoted version of the identifier ident.      """Return a quoted version of the identifier ident.
# Line 135  class PostGISConnection: Line 148  class PostGISConnection:
148    
149      def GeometryTables(self):      def GeometryTables(self):
150          """Return a list with the names of all tables with a geometry column"""          """Return a list with the names of all tables with a geometry column"""
151    
152            # The query is basically taken from the psql v. 7.2.1.  When
153            # started with -E it prints the queries used for internal
154            # commands such as \d, which does mostly what we need here.
155          cursor = self.connection.cursor()          cursor = self.connection.cursor()
156          cursor.execute("SELECT f_table_name FROM geometry_columns;")          cursor.execute("SELECT c.relname FROM pg_class c"
157                           " WHERE c.relkind IN ('r', 'v')"
158                                 # Omit the system tables
159                                 " AND c.relname !~ '^pg_'"
160                                 # Omit the special PostGIS tables
161                                 " AND c.relname NOT IN ('geometry_columns',"
162                                                       " 'spatial_ref_sys')"
163                                " AND %d in (SELECT a.atttypid FROM pg_attribute a"
164                                           " WHERE a.attrelid = c.oid)"
165                           " ORDER BY c.relname;", (self.geometry_type,))
166          result = [row[0] for row in cursor.fetchall()]          result = [row[0] for row in cursor.fetchall()]
167          self.connection.commit()          self.connection.commit()
168          return result          return result
169    
170        def table_columns(self, tablename):
171            """Experimental: return information about the columns of a table
172    
173            Return value is a list of (name, type) pairs where name is the
174            name of the column and type either one of the field type columns
175            or the string 'geometry' indicating a geometry column.
176    
177            The intended use of this method is for table selection dialogs
178            which need to determine which columns are usable as id or
179            geometry columns respectively.  Suitable id columns will have
180            type FIELDTYPE_INT and geometry columns will have 'geometry'.
181            """
182            result = []
183            cursor = self.connection.cursor()
184    
185            # This query is taken basically from the \d command of psql
186            # 7.2.1
187            cursor.execute("SELECT a.attname, a.atttypid, a.attnum"
188                           " FROM pg_class c, pg_attribute a"
189                                " WHERE c.relname = %s AND a.attrelid = c.oid"
190                           " ORDER BY a.attnum;", (tablename,))
191    
192            for row in cursor.fetchall():
193                col_name, col_type, col_attnum = row
194                col = None
195                if col_attnum < 1:
196                    # It's a system column.  Only the OID is interesting
197                    # here
198                    if col_name == "oid":
199                        col = (col_name, _raw_type_map[col_type])
200                else:
201                    # If it's an integer
202                    thuban_type = _raw_type_map.get(col_type)
203                    if thuban_type is not None:
204                        col = (col_name, thuban_type)
205                    elif row[1] == self.geometry_type:
206                        col = (col_name, "geometry")
207                if col is not None:
208                    result.append(col)
209    
210            return result
211    
212      def cursor(self):      def cursor(self):
213          """Return a DB API 2.0 cursor for the database"""          """Return a DB API 2.0 cursor for the database"""
214          return self.connection.cursor()          return self.connection.cursor()
# Line 175  class PostGISTable: Line 243  class PostGISTable:
243      descriptions returned by Columns() and other methods.      descriptions returned by Columns() and other methods.
244      """      """
245    
246      def __init__(self, db, tablename):      def __init__(self, db, tablename, id_column = None):
247          """Initialize the PostGISTable.          """Initialize the PostGISTable.
248    
249          The db parameter should be an instance of PostGISConnection and          The db parameter should be an instance of PostGISConnection and
250          tablename the name of a table in the database represented by db.          tablename the name of a table in the database represented by db.
251    
252            The id_column parameter should be the name of a column in the
253            table that can be used to identify rows.  The column must have
254            the type integer and be unique and not null.
255    
256            For backwards compatibility reasons, the id_column parameter is
257            optional.  If not given the table must have a column called
258            'gid' which is used as the id_column.  New code should always
259            provide this parameter.
260          """          """
261          self.db = db          self.db = db
262          self.tablename = tablename          self.tablename = tablename
263          # Tablename quoted for use in SQL statements.          # Tablename quoted for use in SQL statements.
264          self.quoted_tablename = quote_identifier(tablename)          self.quoted_tablename = quote_identifier(tablename)
265    
266            if not id_column:
267                id_column = "gid"
268            self.id_column = id_column
269            # id column name quoted for use in SQL statements.
270            self.quoted_id_column = quote_identifier(id_column)
271    
272          # Map column names and indices to column objects.          # Map column names and indices to column objects.
273          self.column_map = {}          self.column_map = {}
274    
# Line 199  class PostGISTable: Line 282  class PostGISTable:
282          description = cursor.description          description = cursor.description
283    
284          for i in range(len(description)):          for i in range(len(description)):
285              for pgtyp, tabletyp in type_map:              col = self._create_col_from_description(i, description[i])
286                  if pgtyp == description[i][1]:              if col is not None:
287                      col = PostGISColumn(description[i][0], tabletyp,                  self.columns.append(col)
                                         len(self.columns))  
                     break  
             else:  
                 if description[i][1] == self.db.geometry_type:  
                     self.geometry_column = description[i][0]  
                     self.quoted_geo_col =quote_identifier(self.geometry_column)  
                 # No matching table type. Ignore the column.  
                 # FIXME: We should at least print a warning about  
                 # ignored columns  
                 continue  
             self.columns.append(col)  
288    
289          for col in self.columns:          for col in self.columns:
290              self.column_map[col.name] = col              self.column_map[col.name] = col
# Line 224  class PostGISTable: Line 296  class PostGISTable:
296                                           for col in self.columns]),                                           for col in self.columns]),
297                                self.quoted_tablename))                                self.quoted_tablename))
298    
299        def _create_col_from_description(self, index, description):
300            """Return the column object for the column described by description
301    
302            The parameter index is the index of the column.  The description
303            is a sequence taken from the cursor's description attribute for
304            the column.  That means description[0] is the name of the column
305            and description[1] the type.
306    
307            Return None if the column can't be represented for some reason,
308            e.g. because its type is not yet supported or needs to be
309            treated in some special way.  Derived classes may extend this
310            method.
311            """
312            for pgtyp, tabletyp in type_map:
313                if pgtyp == description[1]:
314                    return PostGISColumn(description[0], tabletyp,
315                                         len(self.columns))
316            return None
317    
318      def DBConnection(self):      def DBConnection(self):
319          """Return the dbconnection used by the table"""          """Return the dbconnection used by the table"""
320          return self.db          return self.db
321    
322        def IDColumn(self):
323            """Return the column description object for the id column.
324    
325            If the oid column was used as the id column, the return value is
326            not one of the regular column objects that would be returned by
327            e.g. the Column() method, but it still has meaningful name
328            attribute.
329            """
330            if self.id_column == "oid":
331                return PostGISColumn(self.id_column, table.FIELDTYPE_INT, None)
332            return self.column_map[self.id_column]
333    
334      def TableName(self):      def TableName(self):
335          """Return the name of the table in the database"""          """Return the name of the table in the database"""
336          return self.tablename          return self.tablename
# Line 264  class PostGISTable: Line 367  class PostGISTable:
367      def RowIdToOrdinal(self, gid):      def RowIdToOrdinal(self, gid):
368          """Return the row ordinal given its id"""          """Return the row ordinal given its id"""
369          cursor = self.db.cursor()          cursor = self.db.cursor()
370          cursor.execute("SELECT count(*) FROM %s WHERE gid < %d;"          cursor.execute("SELECT count(*) FROM %s WHERE %s < %d;"
371                         % (self.quoted_tablename, gid))                         % (self.quoted_tablename, self.quoted_id_column, gid))
372          return cursor.fetchone()[0]          return cursor.fetchone()[0]
373    
374      def RowOrdinalToId(self, num):      def RowOrdinalToId(self, num):
375          """Return the rowid for given its ordinal"""          """Return the rowid for given its ordinal"""
376          cursor = self.db.cursor()          cursor = self.db.cursor()
377          cursor.execute("SELECT gid FROM %s LIMIT 1 OFFSET %d;"          cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d;"
378                         % (self.quoted_tablename, num))                         % (self.quoted_id_column, self.quoted_tablename, num))
379          return cursor.fetchone()[0]          return cursor.fetchone()[0]
380    
381      def ReadRowAsDict(self, row, row_is_ordinal = 0):      def ReadRowAsDict(self, row, row_is_ordinal = 0):
# Line 280  class PostGISTable: Line 383  class PostGISTable:
383          if row_is_ordinal:          if row_is_ordinal:
384              stmt = self.query_stmt + " LIMIT 1 OFFSET %d" % row              stmt = self.query_stmt + " LIMIT 1 OFFSET %d" % row
385          else:          else:
386              stmt = self.query_stmt + " WHERE gid = %d" % row              stmt = self.query_stmt + " WHERE %s = %d" % (self.quoted_id_column,
387                                                             row)
388          cursor.execute(stmt)          cursor.execute(stmt)
389          result = {}          result = {}
390          for col, value in zip(self.columns, cursor.fetchone()):          for col, value in zip(self.columns, cursor.fetchone()):
# Line 294  class PostGISTable: Line 398  class PostGISTable:
398                      (self.column_map[col].quoted_name, self.quoted_tablename,                      (self.column_map[col].quoted_name, self.quoted_tablename,
399                       row))                       row))
400          else:          else:
401              stmt = ("SELECT %s FROM %s WHERE gid = %d" %              stmt = ("SELECT %s FROM %s WHERE %s = %d" %
402                      (self.column_map[col].quoted_name, self.quoted_tablename,                      (self.column_map[col].quoted_name, self.quoted_tablename,
403                       row))                       self.quoted_id_column, row))
404          cursor.execute(stmt)          cursor.execute(stmt)
405          return cursor.fetchone()[0]          return cursor.fetchone()[0]
406    
# Line 328  class PostGISTable: Line 432  class PostGISTable:
432              right_template = "%s"              right_template = "%s"
433              params = (right,)              params = (right,)
434    
435          query = "SELECT gid FROM %s WHERE %s %s %s ORDER BY gid;" \          query = "SELECT %s FROM %s WHERE %s %s %s ORDER BY %s;" \
436                  % (self.quoted_tablename, left.quoted_name, comparison,                  % (self.quoted_id_column, self.quoted_tablename,
437                     right_template)                     left.quoted_name, comparison, right_template,
438                       self.quoted_id_column)
439    
440          cursor = self.db.cursor()          cursor = self.db.cursor()
441          cursor.execute(query, params)          cursor.execute(query, params)
# Line 381  class PostGISShapeStore(PostGISTable): Line 486  class PostGISShapeStore(PostGISTable):
486    
487      """Shapestore interface to a table in a PostGIS database"""      """Shapestore interface to a table in a PostGIS database"""
488    
489        def __init__(self, db, tablename, id_column = "gid",
490                     geometry_column = None):
491            """Initialize the PostGISShapeStore.
492    
493            The db parameter should be an instance of PostGISConnection and
494            tablename the name of a table in the database represented by db.
495    
496            The id_column parameter should be the name of a column in the
497            table that can be used to identify rows.  The column must have
498            the type integer and be unique and not null.
499    
500            The geometry_column paramter, if given, should be the name of
501            the geometry column to use.  If the name given is not a geometry
502            column, raise a ValueError.
503    
504            If no geometry_column is given, the table must have exactly one
505            geometry column.  If it has more than one and the
506            geometry_column is not given, a ValueError will be raised.
507            """
508            self.geometry_column = geometry_column
509            self.geometry_column_was_given = geometry_column is not None
510            PostGISTable.__init__(self, db, tablename, id_column)
511    
512            # For convenience, we have a quoted version of the geometry
513            # column in self.quoted_geo_col
514            self.quoted_geo_col = quote_identifier(self.geometry_column)
515    
516      def _fetch_table_information(self):      def _fetch_table_information(self):
517          """Extend inherited method to retrieve the SRID"""          """Extend inherited method to retrieve the SRID and shape type"""
518          PostGISTable._fetch_table_information(self)          PostGISTable._fetch_table_information(self)
519    
520            # First, try to get it from the geometry_columns table.
521            cursor = self.db.cursor()
522            cursor.execute("SELECT srid, type FROM geometry_columns"
523                           " WHERE f_table_name = %s AND f_geometry_column=%s",
524                           (self.tablename, self.geometry_column))
525            row = cursor.fetchone()
526            if row is not None:
527                self.srid = row[0]
528                self.shape_type = shapetype_map.get(row[1])
529                return
530    
531            # The table is probably really a view and thus not in
532            # geometry_columns.  Use a different approach
533            cursor = self.db.cursor()
534            cursor.execute("SELECT DISTINCT SRID(%s) FROM %s;" %
535                           (quote_identifier(self.geometry_column),
536                            self.tablename))
537            row = cursor.fetchone()
538            if row is not None:
539                self.srid = row[0]
540                # Try to see whether there's another one
541                row = cursor.fetchone()
542                if row is not None:
543                    # There are at least two different srids.  We don't
544                    # support that
545                    self.srid = None
546    
547          cursor = self.db.cursor()          cursor = self.db.cursor()
548          cursor.execute("SELECT srid FROM geometry_columns"          cursor.execute("SELECT DISTINCT GeometryType(%s) FROM %s;"
549                         " WHERE f_table_name = %s", (self.tablename,))                         % (quote_identifier(self.geometry_column),
550          self.srid = cursor.fetchone()[0]                            self.tablename))
551            row = cursor.fetchone()
552            if row is not None:
553                self.shape_type = shapetype_map.get(row[0])
554                # Try to see whether there's another one
555                row = cursor.fetchone()
556                if row is not None:
557                    # There are at least two different srids.  We don't
558                    # support that
559                    self.shape_type = None
560    
561        def _create_col_from_description(self, index, description):
562            """Extend the inherited method to find geometry columns
563    
564            If the column indicated by the parameters is a geometry column,
565            record its name in self.geometry_column and a quoted version in
566            self.quoted_geo_col.  In any case return the return value of the
567            inherited method.
568            """
569            col = PostGISTable._create_col_from_description(self, index,
570                                                            description)
571            col_name, col_type = description[:2]
572            if self.geometry_column_was_given:
573                if (col_name == self.geometry_column
574                    and col_type != self.db.geometry_type):
575                    raise TypeError("Column %s in %s is not a geometry column"
576                                    % (self.geometry_column, self.tablename))
577            else:
578                if col is None:
579                    if description[1] == self.db.geometry_type:
580                        # The column is a geometry column.  If the name of
581                        # the geometry column was not given to the
582                        # constructor, and we encounter two geometry
583                        # columns, raise a value error
584                        if self.geometry_column is None:
585                            self.geometry_column = description[0]
586                        else:
587                            raise TypeError("Table %s has two geometry columns"
588                                            " and no column name was given"
589                                            % (self.tablename,))
590            return col
591    
592      def Table(self):      def Table(self):
593          """Return self since a PostGISShapeStore is its own table."""          """Return self since a PostGISShapeStore is its own table."""
# Line 398  class PostGISShapeStore(PostGISTable): Line 598  class PostGISShapeStore(PostGISTable):
598          """          """
599          return None          return None
600    
601        def GeometryColumn(self):
602            """Return the column description object for the geometry column
603    
604            There's currently no FIELDTYPE constant for this column, so the
605            return value is not a regular column object that could also be
606            returned from e.g. the Column() method.  Only the name attribute
607            of the return value is meaningful at the moment.
608            """
609            return PostGISColumn(self.geometry_column, None, None)
610    
611      def ShapeType(self):      def ShapeType(self):
612          """Return the type of the shapes in the shapestore."""          """Return the type of the shapes in the shapestore."""
613          cursor = self.db.cursor()          return self.shape_type
         cursor.execute("SELECT type FROM geometry_columns WHERE"  
                        " f_table_name=%s", (self.tablename,))  
         result = cursor.fetchone()[0]  
         cursor.close()  
         return shapetype_map[result]  
614    
615      def RawShapeFormat(self):      def RawShapeFormat(self):
616          """Return the raw data format of the shape data.          """Return the raw data format of the shape data.
# Line 442  class PostGISShapeStore(PostGISTable): Line 647  class PostGISShapeStore(PostGISTable):
647    
648      def Shape(self, shapeid):      def Shape(self, shapeid):
649          cursor = self.db.cursor()          cursor = self.db.cursor()
650          cursor.execute("SELECT AsText(%s) FROM %s WHERE gid=%d"          cursor.execute("SELECT AsText(%s) FROM %s WHERE %s=%d"
651                         % (self.quoted_geo_col, self.quoted_tablename, shapeid))                         % (self.quoted_geo_col, self.quoted_tablename,
652                              self.quoted_id_column, shapeid))
653          wkt = cursor.fetchone()[0]          wkt = cursor.fetchone()[0]
654          cursor.close()          cursor.close()
655          return PostGISShape(shapeid, wkt)          return PostGISShape(shapeid, wkt)
656    
657      def AllShapes(self):      def AllShapes(self):
658          cursor = self.db.cursor()          cursor = self.db.cursor()
659          cursor.execute("SELECT gid, AsText(%s) FROM %s ORDER BY gid"          cursor.execute("SELECT %s, AsText(%s) FROM %s ORDER BY %s"
660                         % (self.quoted_geo_col, self.quoted_tablename))                         % (self.quoted_id_column, self.quoted_geo_col,
661                              self.quoted_tablename, self.quoted_id_column))
662          while 1:          while 1:
663              result = cursor.fetchone()              result = cursor.fetchone()
664              if result is None:              if result is None:
# Line 467  class PostGISShapeStore(PostGISTable): Line 674  class PostGISShapeStore(PostGISTable):
674                  % (left, bottom, left, top, right, top, right, bottom,                  % (left, bottom, left, top, right, top, right, bottom,
675                     left, bottom))                     left, bottom))
676          cursor = self.db.cursor()          cursor = self.db.cursor()
677          cursor.execute("SELECT gid, AsText(%s) FROM %s"          cursor.execute("SELECT %(gid)s, AsText(%(geom)s) FROM %(table)s"
678                       " WHERE %s && GeometryFromText('%s', %d) ORDER BY gid"                       " WHERE %(geom)s && GeometryFromText('%(box)s', %(srid)d)"
679                         % (self.quoted_geo_col, self.quoted_tablename,                         " ORDER BY %(gid)s"
680                            self.quoted_geo_col, geom, self.srid))                         % {"table": self.quoted_tablename,
681                              "geom": self.quoted_geo_col,
682                              "gid": self.quoted_id_column,
683                              "box": geom,
684                              "srid": self.srid})
685          while 1:          while 1:
686              result = cursor.fetchone()              result = cursor.fetchone()
687              if result is None:              if result is None:
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