/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/postgisdb.py
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revision 2096 by bh, Thu Mar 11 13:50:53 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, id_column = "gid"):      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
# Line 184  class PostGISTable: Line 252  class PostGISTable:
252          The id_column parameter should be the name of a column in the          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          table that can be used to identify rows.  The column must have
254          the type integer and be unique and not null.          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          self.id_column = id_column
269          # id column name quoted for use in SQL statements.          # id column name quoted for use in SQL statements.
270          self.quoted_id_column = quote_identifier(id_column)          self.quoted_id_column = quote_identifier(id_column)
# Line 244  class PostGISTable: Line 319  class PostGISTable:
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 427  class PostGISShapeStore(PostGISTable): Line 514  class PostGISShapeStore(PostGISTable):
514          self.quoted_geo_col = quote_identifier(self.geometry_column)          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()          cursor = self.db.cursor()
522          cursor.execute("SELECT srid FROM geometry_columns"          cursor.execute("SELECT srid, type FROM geometry_columns"
523                         " WHERE f_table_name = %s AND f_geometry_column=%s",                         " WHERE f_table_name = %s AND f_geometry_column=%s",
524                         (self.tablename, self.geometry_column))                         (self.tablename, self.geometry_column))
525          self.srid = cursor.fetchone()[0]          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()
548            cursor.execute("SELECT DISTINCT GeometryType(%s) FROM %s;"
549                           % (quote_identifier(self.geometry_column),
550                              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):      def _create_col_from_description(self, index, description):
562          """Extend the inherited method to find geometry columns          """Extend the inherited method to find geometry columns
# Line 475  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 AND f_geometry_column=%s",  
                        (self.tablename, self.geometry_column))  
         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.
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