[gnue] r9087 - trunk/gnue-common/src/utils

[reinhard]

Author: reinhard
Date: 2006-11-29 10:27:47 -0600 (Wed, 29 Nov 2006)
New Revision: 9087

Added:
   trunk/gnue-common/src/utils/datatypes.py
Log:
Added module to help with conversion of data into GNUe's standard datatypes.


Added: trunk/gnue-common/src/utils/datatypes.py
===================================================================
--- trunk/gnue-common/src/utils/datatypes.py    2006-11-29 10:14:20 UTC (rev 
9086)
+++ trunk/gnue-common/src/utils/datatypes.py    2006-11-29 16:27:47 UTC (rev 
9087)
@@ -0,0 +1,171 @@
+# GNU Enterprise Common Library - Utilities - Datatype conversion
+#
+# Copyright 2001-2006 Free Software Foundation
+#
+# This file is part of GNU Enterprise
+#
+# GNU Enterprise is free software; you can redistribute it
+# and/or modify it under the terms of the GNU General Public
+# License as published by the Free Software Foundation; either
+# version 2, or (at your option) any later version.
+#
+# GNU Enterprise is distributed in the hope that it will be
+# useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
+# PURPOSE. See the GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public
+# License along with program; see the file COPYING. If not,
+# write to the Free Software Foundation, Inc., 59 Temple Place
+# - Suite 330, Boston, MA 02111-1307, USA.
+#
+# $Id: version.py 9059 2006-11-23 10:17:50Z reinhard $
+"""
+Helper functions for datatype conversion.
+"""
+
+__all__ = ['convert', 'ConversionError']
+
+import datetime
+import mx.DateTime
+
+from gnue.common.utils import GDateTime
+
+
+# =============================================================================
+# Convert a value to a given target datatype
+# =============================================================================
+
+def convert(value, datatype, length, scale):
+    """
+    Convert a value to a given target datatype.
+
+    @param value: The value to convert.
+    @param datatype: Can be "text", "number", "date", "time", "datetime", or
+        "boolean".
+    @param length: Length for "text" and "number" datatypes.
+    @param scale: Scale for "number" datatype.
+    """
+
+    # It might be better style to have separate functions "convert_text",
+    # "convert_number", etc., however I strongly believe that keeping
+    # everything in a single function helps improving the performance.
+    #   -- Reinhard
+
+    if value is None:
+        # "None" is always valid, independent of data type
+        result = None
+
+    elif datatype == "text":
+        if isinstance(value, unicode):
+            result = value
+        elif isinstance(value, str):
+            result = unicode(value)
+        else:
+            result = unicode(str(value))
+
+    elif datatype == "number":
+        if scale:
+            result = float(value)
+        else:
+            result = int(value)
+      
+    elif datatype == "date":
+        if isinstance(value, basestring):
+            value = GDateTime.parseISO(value)
+
+        if isinstance(value, datetime.datetime):
+            result = value.date()
+
+        elif isinstance(value, datetime.date):
+            result = value
+
+        elif isinstance(value, mx.DateTime.DateTimeType):
+            result = datetime.date(value.year, value.month, value.day)
+
+        else:
+            raise ConversionError(value, datatype)
+
+    elif datatype == "time":
+        if isinstance(value, basestring):
+            value = GDateTime.parseISO(value)
+
+        if isinstance(value, datetime.datetime):
+            result = value.time()
+
+        elif isinstance(value, datetime.time):
+            result = value
+
+        elif isinstance(value, datetime.timedelta):
+            result = (datetime.datetime(1, 1, 1) + value).time()
+
+        elif isinstance(value, mx.DateTime.DateTimeType) or \
+                isinstance(value, mx.DateTime.DateTimeDeltaType):
+            result = datetime.time(value.hour, value.minute, int(value.second),
+                int((value.second - int(value.second)) * 1000000))
+
+        else:
+            raise ConversionError(value, datatype)
+
+    elif datatype == "datetime":
+        if isinstance(value, basestring):
+            value = GDateTime.parseISO(value)
+
+        if isinstance(value, datetime.datetime):
+            result = value
+
+        elif isinstance(value, datetime.date):
+            result = datetime.datetime(value.year, value.month, value.day)
+
+        elif isinstance(value, mx.DateTime.DateTimeType):
+            result = datetime.datetime(value.year, value.month, value.day,
+                value.hour, value.minute, int(value.second),
+                int((value.second - int(value.second)) * 1000000))
+
+        else:
+            raise ConversionError(value, datatype)
+
+    elif datatype == "boolean":
+        if value in [0, "0", "f", "F", "false", "FALSE", "n", "N", "no", "NO",
+                False]:
+            result = False
+        elif value in [1, "1", "t", "T", "true", "TRUE", "y", "Y", "yes", 
"YES",
+                True]:
+            result = True
+        else:
+            raise ConversionError(value, datatype)
+
+    else:
+        # Unknown datatype
+        raise ConversionError(value, datatype)
+
+    return result
+
+
+# =============================================================================
+# Exceptions
+# =============================================================================
+
+class ConversionError(Exception):
+    """
+    Unable to convert the given value to the requested datatype.
+    """
+
+    def __init__(self, value, datatype):
+        Exception.__init__(self,
+                "Unable to convert %(value)r to datatype %(datatype)s" % {
+                    'value': value,
+                    'datatype': datatype})
+
+
+# =============================================================================
+# Self test code
+# =============================================================================
+
+if __name__ == '__main__':
+    print repr(convert('abc', 'text', 0, 0))
+    print repr(convert('123', 'number', 0, 0))
+    print repr(convert(123, 'number', 10, 2))
+    print repr(convert('2006-11-29', 'date', 0, 0))
+    print repr(convert('17:18:19', 'time', 0, 0))
+    print repr(convert(1, 'boolean', 0, 0))