/[thuban]/branches/WIP-pyshapelib-bramz/Thuban/Model/transientdb.py
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revision 849 by bh, Wed May 7 11:55:31 2003 UTC revision 1511 by bh, Tue Jul 29 14:48:57 2003 UTC
# Line 18  __version__ = "$Revision$" Line 18  __version__ = "$Revision$"
18  # $Source$  # $Source$
19  # $Id$  # $Id$
20    
 import os  
 import weakref  
21  from sqlite import connect  from sqlite import connect
22    
23    from base import TitledObject
24    
25  import table  import table
26    
27  sql_type_map = {  sql_type_map = {
# Line 240  class TransientTableBase(table.OldTableI Line 240  class TransientTableBase(table.OldTableI
240              result.append(row[0])              result.append(row[0])
241          return result          return result
242    
243        def Width(self, col):
244            """Return the maximum width of values in the column
245    
246            The return value is the the maximum length of string
247            representation of the values in the column (represented by index
248            or name).
249            """
250            max = 0
251    
252            type  = self.column_map[col].type
253            iname = self.column_map[col].internal_name
254            cursor = self.db.cursor()
255            cursor.execute("SELECT %s FROM %s;" % (iname, self.tablename))
256            values = [ i[0] for i in cursor.fetchall()]
257            if not values:
258                return None
259    
260            if type == table.FIELDTYPE_DOUBLE:
261                format = "%.12f"
262            elif type == table.FIELDTYPE_INT:
263                format = "%d"
264            else:
265                format = "%s"
266            for value in values:
267                if value is None: continue
268                l = len(format % value)
269                if l > max:
270                    max = l
271    
272            return max
273    
274      def SimpleQuery(self, left, comparison, right):      def SimpleQuery(self, left, comparison, right):
275          """Return the indices of all rows that matching a condition.          """Return the indices of all rows that matching a condition.
276    
# Line 280  class TransientTableBase(table.OldTableI Line 311  class TransientTableBase(table.OldTableI
311              result.append(row[0])              result.append(row[0])
312          return result          return result
313    
314        def Dependencies(self):
315            """Placeholder for a method in a derived class.
316    
317            Return a sequence with the tables and other data objects that
318            self depends on.
319            """
320            raise NotImplementedError
321    
322    
323  class TransientTable(TransientTableBase):  class TransientTable(TitledObject, TransientTableBase):
324    
325      """A Table in a transient DB that starts as the copy of a Thuban Table."""      """A Table in a transient DB that starts as the copy of a Thuban Table."""
326    
# Line 292  class TransientTable(TransientTableBase) Line 331  class TransientTable(TransientTableBase)
331          interface.          interface.
332          """          """
333          TransientTableBase.__init__(self, transient_db)          TransientTableBase.__init__(self, transient_db)
334            TitledObject.__init__(self, table.Title())
335          self.create(table)          self.create(table)
336    
337      def create(self, table):      def create(self, table):
# Line 325  class TransientTable(TransientTableBase) Line 365  class TransientTable(TransientTableBase)
365    
366    
367    
368  class TransientJoinedTable(TransientTableBase):  class TransientJoinedTable(TitledObject, TransientTableBase):
369    
370      """A Table in the transient DB that contains a join of two tables"""      """A Table in the transient DB that contains a join of two tables"""
371    
372      def __init__(self, transient_db, left_table, left_field,      def __init__(self, transient_db, left_table, left_field,
373                   right_table, right_field = None):                   right_table, right_field = None, outer_join = False):
374          """Create a new table in the transient DB as a join of two tables.          """Create a new table in the transient DB as a join of two tables.
375    
376          Both input tables, left_table and right_table must have a          Both input tables, left_table and right_table must have a
377          transient_table method that returns a table object for a table          transient_table method that returns a table object for a table
378          in the trnsient database. The join is performed on the condition          in the transient database. The join is performed on the condition
379          that the value of the left_field column the the left table is          that the value of the left_field column the the left table is
380          equal to the value of the right_field in the right_table.          equal to the value of the right_field in the right_table.
381    
382          The joined table contains all columns of the input tables with          The joined table contains all columns of the input tables,
383          one exception: Any column in the right_table with the same name          however, the column names of the right table may be changed
384          as one of the columns in the left_table will be omitted. This is          slightly to make them unique in the joined table. This is
385          somewhat of an implementation detail, but is done so that the          currently done by appending a sufficient number of underscores
386          column names of the joined table can be the same as the column          ('_').
         names of the input tables without having to create prefixes.  
387          """          """
388          TransientTableBase.__init__(self, transient_db)          TransientTableBase.__init__(self, transient_db)
389            self.dependencies = (left_table, right_table)
390          self.left_table = left_table.transient_table()          self.left_table = left_table.transient_table()
391          self.left_field = left_field          self.left_field = left_field
392          self.right_table = right_table.transient_table()          self.right_table = right_table.transient_table()
# Line 354  class TransientJoinedTable(TransientTabl Line 394  class TransientJoinedTable(TransientTabl
394              self.right_field = right_field              self.right_field = right_field
395          else:          else:
396              self.right_field = self.left_field              self.right_field = self.left_field
397            self.outer_join = outer_join
398    
399            title = "Join of %(left)s and %(right)s" \
400                    % {"left": self.left_table.Title(),
401                       "right": self.right_table.Title()}
402            TitledObject.__init__(self, title)
403    
404          self.create()          self.create()
405    
406      def create(self):      def create(self):
# Line 362  class TransientJoinedTable(TransientTabl Line 409  class TransientJoinedTable(TransientTabl
409    
410          self.right_table.ensure_index(self.right_field)          self.right_table.ensure_index(self.right_field)
411    
412            # determine the internal column names to join on before
413            # coalescing the column information because if the external
414            # column names are the same they will be mapped to the same
415            # internal name afterwards.
416            internal_left_col = self.left_table.orig_to_internal[self.left_field]
417            internal_right_col =self.right_table.orig_to_internal[self.right_field]
418    
419          # Coalesce the column information          # Coalesce the column information
420          visited = {}          visited = {}
421          columns = []          columns = []
422          for col in self.left_table.columns + self.right_table.columns:          newcolumns = []
423              if col.name in visited:          for table in (self.left_table, self.right_table):
424                  # We can't allow multiple columns with the same original              for col in table.Columns():
425                  # name, so omit this one. FIXME: There should be a                  colname = col.name
426                  # better solution.                  # We can't allow multiple columns with the same
427                  continue                  # original name, so append '_' to this one until
428              columns.append(col)                  # it is unique.
429          TransientTableBase.create(self, columns)                  # FIXME: There should be a better solution.
430                    while colname in visited:
431                        colname = colname + '_'
432                    columns.append((table.tablename, col))
433                    newcol = ColumnReference(colname, col.type,
434                                                "Col%03d" % (len(newcolumns)+1))
435                    newcolumns.append(newcol)
436                    visited[colname] = 1
437            TransientTableBase.create(self, newcolumns)
438    
439          # Copy the joined data to the table.          # Copy the joined data to the table.
440          internal_names = [col.internal_name for col in self.columns]          newinternal_names = [col.internal_name for col in self.columns]
441            internal_references = ["%s.%s" % (table, col.internal_name)
442                                                        for table, col in columns]
443            if self.outer_join:
444                join_operator = 'LEFT OUTER JOIN'
445            else:
446                join_operator = 'JOIN'
447          stmt = ("INSERT INTO %s (id, %s) SELECT %s.id, %s FROM %s"          stmt = ("INSERT INTO %s (id, %s) SELECT %s.id, %s FROM %s"
448                  " JOIN %s ON %s = %s;"                  " %s %s ON %s.%s = %s.%s;"
449                  % (self.tablename,                  % (self.tablename,
450                     ", ".join(internal_names),                     ", ".join(newinternal_names),
451                       self.left_table.tablename,
452                       ", ".join(internal_references),
453                     self.left_table.tablename,                     self.left_table.tablename,
454                     ", ".join(internal_names),                     join_operator,
455                       self.right_table.tablename,
456                     self.left_table.tablename,                     self.left_table.tablename,
457                       internal_left_col,
458                     self.right_table.tablename,                     self.right_table.tablename,
459                     self.orig_to_internal[self.left_field],                     internal_right_col))
                    self.orig_to_internal[self.right_field]))  
460          self.db.execute(stmt)          self.db.execute(stmt)
461    
462        def Dependencies(self):
463            """Return a tuple with the two tables the join depends on."""
464            return self.dependencies
465    
466        def JoinType(self):
467            """Return the type of the join (either 'INNER' or 'LEFT OUTER')"""
468            if self.outer_join:
469                return "LEFT OUTER"
470            else:
471                return "INNER"
472    
473    
474  class AutoTransientTable(table.OldTableInterfaceMixin):  class AutoTransientTable(TitledObject, table.OldTableInterfaceMixin):
475    
476      """Table that copies data to a transient table on demand.      """Table that copies data to a transient table on demand.
477    
# Line 398  class AutoTransientTable(table.OldTableI Line 480  class AutoTransientTable(table.OldTableI
480      """      """
481    
482      def __init__(self, transient_db, table):      def __init__(self, transient_db, table):
483            TitledObject.__init__(self, table.Title())
484          self.transient_db = transient_db          self.transient_db = transient_db
485          self.table = table          self.table = table
486          self.t_table = None          self.t_table = None
# Line 465  class AutoTransientTable(table.OldTableI Line 548  class AutoTransientTable(table.OldTableI
548          # Make sure to use the column object of the transient table. The          # Make sure to use the column object of the transient table. The
549          # left argument is always a column object so we can just ask the          # left argument is always a column object so we can just ask the
550          # t_table for the right object.          # t_table for the right object.
551          return self.t_table.SimpleQuery(self.t_table.Column(left.name),          if hasattr(right, "name"):
552                                          comparison, right)              return self.t_table.SimpleQuery(self.t_table.Column(left.name),
553                                                comparison,
554                                                self.t_table.Column(right.name))
555            else:
556                return self.t_table.SimpleQuery(self.t_table.Column(left.name),
557                                                comparison, right)
558    
559        def Dependencies(self):
560            """Return a tuple containing the original table"""
561            return (self.table,)
562    
563        def Width(self, col):
564            return self.table.Width(col)
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