add support for null values in D, F and L parsing

dbfread/field_parser.py

@@ -22,7 +22,7 @@ def __repr__(self):
             # Make sure the string starts with "b'" in
             # "InvalidValue(b'value here')".
             text = 'b' + text
-            
+
         return 'InvalidValue({})'.format(text)
 
 class FieldParser:
@@ -91,13 +91,13 @@ def parseD(self, field, data):
         try:
             return datetime.date(int(data[:4]), int(data[4:6]), int(data[6:8]))
         except ValueError:
-            if data.strip(b' 0') == b'':
+            if data.strip(b' 0\0') == b'':
                 # A record containing only spaces and/or zeros is
                 # a NULL value.
                 return None
             else:
                 raise ValueError('invalid date {!r}'.format(data))
-    
+
     def parseF(self, field, data):
         """Parse float field and return float or None"""
         # In some files * is used for padding.
@@ -119,7 +119,7 @@ def parseL(self, field, data):
             return True
         elif data in b'FfNn':
             return False
-        elif data in b'? ':
+        elif data in b'? \0':
             return None
         else:
             # Todo: return something? (But that would be misleading!)
@@ -162,7 +162,7 @@ def parseN(self, field, data):
         Returns int, float or None if the field is empty.
         """
         # In some files * is used for padding.
-        data = data.strip().strip(b'*')
+        data = data.strip().strip(b'*\0')
 
         try:
             return int(data)
@@ -211,7 +211,7 @@ def parseT(self, field, data):
                 return None
         else:
             return None
-            
+
     def parseY(self, field, data):
         """Parse currency field (Y) and return decimal.Decimal.