Package dbf
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Source Code for Package dbf

  1  """ 
  2  Copyright 
  3  ========= 
  4      - Copyright: 2008-2009 Ad-Mail, Inc -- All rights reserved. 
  5      - Author: Ethan Furman 
  6      - Contact: ethanf@admailinc.com 
  7      - Organization: Ad-Mail, Inc. 
  8      - Version: 0.87.003 as of 03 Dec 2009 
  9   
 10  Redistribution and use in source and binary forms, with or without 
 11  modification, are permitted provided that the following conditions are met: 
 12      - Redistributions of source code must retain the above copyright 
 13        notice, this list of conditions and the following disclaimer. 
 14      - Redistributions in binary form must reproduce the above copyright 
 15        notice, this list of conditions and the following disclaimer in the 
 16        documentation and/or other materials provided with the distribution. 
 17      - Neither the name of Ad-Mail, Inc nor the 
 18        names of its contributors may be used to endorse or promote products 
 19        derived from this software without specific prior written permission. 
 20   
 21  THIS SOFTWARE IS PROVIDED BY Ad-Mail, Inc ''AS IS'' AND ANY 
 22  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 
 23  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
 24  DISCLAIMED. IN NO EVENT SHALL Ad-Mail, Inc BE LIABLE FOR ANY 
 25  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 
 26  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 27  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 
 28  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
 29  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 
 30  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
 31   
 32  B{I{Summary}} 
 33   
 34  Python package for reading/writing dBase III and VFP 6 tables and memos 
 35   
 36  The entire table is read into memory, and all operations occur on the in-memory 
 37  table, with data changes being written to disk as they occur. 
 38   
 39  Goals:  programming style with databases 
 40      - C{table = dbf.table('table name' [, fielddesc[, fielddesc[, ....]]])} 
 41          - fielddesc examples:  C{name C(30); age N(3,0); wisdom M; marriage D} 
 42      - C{record = [ table.current() | table[int] | table.append() | table.[next|prev|top|bottom|goto]() ]} 
 43      - C{record.field | record['field']} accesses the field 
 44   
 45  NOTE:  Of the VFP data types, auto-increment and null settings are not implemented. 
 46  """ 
 47  import os 
 48  import csv 
 49   
 50  from dbf.dates import Date, DateTime, Time 
 51  from dbf.exceptions import DbfWarning, Bof, Eof, DbfError, DataOverflow, FieldMissing 
 52  from dbf.tables import DbfTable, Db3Table, VfpTable, FpTable, DbfList, DbfCsv 
 53  from dbf.tables import ascii, codepage, encoding, version_map 
 54   
 55  version = (0, 87, 12) 
 56   
 57  __docformat__ = 'epytext' 
 58   
59 -def Table(filename, field_specs='', memo_size=128, ignore_memos=False, \ 60 read_only=False, keep_memos=False, meta_only=False, dbf_type=None, codepage=None):
61 "returns an open table of the correct dbf_type, or creates it if field_specs is given" 62 if dbf_type is not None: 63 dbf_type = dbf_type.lower() 64 if dbf_type == 'db3': 65 return Db3Table(filename, field_specs, memo_size, ignore_memos, read_only, keep_memos, meta_only, codepage) 66 elif dbf_type == 'fp': 67 return FpTable(filename, field_specs, memo_size, ignore_memos, read_only, keep_memos, meta_only, codepage) 68 elif dbf_type == 'vfp': 69 return VfpTable(filename, field_specs, memo_size, ignore_memos, read_only, keep_memos, meta_only, codepage) 70 elif dbf_type == 'dbf': 71 return DbfTable(filename, field_specs, memo_size, ignore_memos, read_only, keep_memos, meta_only, codepage) 72 else: 73 raise TypeError("Unknown table type: %s" % dbf_type) 74 else: 75 possibles = guess_table_type(filename) 76 if len(possibles) == 1: 77 return possibles[0][2](filename, field_specs, memo_size, ignore_memos, \ 78 read_only, keep_memos, meta_only) 79 elif len(possibles) > 1: 80 types = ', '.join(["%s" % item[1] for item in possibles]) 81 abbrs = '[' + ' | '.join(["%s" % item[0] for item in possibles]) + ']' 82 raise DbfError("Table could be any of %s. Please specify %s when opening" % (types, abbrs)) 83 else: 84 raise DbfError("Shouldn't have gotten here -- yell at programmer!")
85 -def index(sequence):
86 "returns integers 0 - len(sequence)" 87 for i in xrange(len(sequence)): 88 yield i
89 -def guess_table_type(filename):
90 reported = table_type(filename) 91 possibles = [] 92 version = reported[0] 93 for tabletype in (Db3Table, FpTable, VfpTable): 94 if version in tabletype._supported_tables: 95 possibles.append((tabletype._versionabbv, tabletype._version, tabletype)) 96 if not possibles: 97 raise DbfError("Tables of type %s not supported" % str(reported)) 98 return possibles
99 -def table_type(filename):
100 "returns text representation of a table's dbf version" 101 base, ext = os.path.splitext(filename) 102 if ext == '': 103 filename = base + '.dbf' 104 if not os.path.exists(filename): 105 raise DbfError('File %s not found' % filename) 106 fd = open(filename) 107 version = fd.read(1) 108 fd.close() 109 fd = None 110 if not version in version_map: 111 raise TypeError("Unknown dbf type: %s (%x)" % (version, ord(version))) 112 return version, version_map[version]
113
114 -def add_fields(table, field_specs):
115 "adds fields to an existing table" 116 table = Table(table) 117 try: 118 table.add_fields(field_specs) 119 finally: 120 table.close()
121 -def delete_fields(table, field_names):
122 "deletes fields from an existing table" 123 table = Table(table) 124 try: 125 table.delete_fields(field_names) 126 finally: 127 table.close()
128 -def export(table, filename='', fields='', format='csv', header=True):
129 "creates a csv or tab-delimited file from an existing table" 130 table = Table(table) 131 try: 132 table.export(filename, fields, format, header) 133 finally: 134 table.close()
135 -def first_record(table):
136 "prints the first record of a table" 137 table = Table(table) 138 try: 139 print str(table[0]) 140 finally: 141 table.close()
142 -def from_csv(csvfile, to_disk=False, filename=None, field_names='', extra_fields='', dbf_type='db3'):
143 """creates a Character table from a csv file 144 to_disk will create a table with the same name 145 filename will be used if provided 146 field_names default to f0, f1, f2, etc, unless specified (list) 147 extra_fields can be used to add additional fields -- should be normal field specifiers (list)""" 148 reader = csv.reader(open(csvfile)) 149 if field_names: 150 field_names = ['%s M' % fn for fn in field_names] 151 else: 152 field_names = ['f0 M'] 153 mtable = Table(':memory:', [field_names[0]], dbf_type=dbf_type) 154 fields_so_far = 1 155 for row in reader: 156 while fields_so_far < len(row): 157 if fields_so_far == len(field_names): 158 field_names.append('f%d M' % fields_so_far) 159 mtable.add_fields(field_names[fields_so_far]) 160 fields_so_far += 1 161 mtable.append(tuple(row)) 162 if not to_disk: 163 if extra_fields: 164 mtable.add_fields(extra_fields) 165 else: 166 if not filename: 167 filename = os.path.splitext(csvfile)[0] 168 length = [1] * len(field_names) 169 for record in mtable: 170 for i in index(record.field_names): 171 length[i] = max(length[i], len(record[i])) 172 fields = mtable.field_names 173 fielddef = [] 174 for i in index(length): 175 if length[i] < 255: 176 fielddef.append('%s C(%d)' % (fields[i], length[i])) 177 else: 178 fielddef.append('%s M' % (fields[i])) 179 if extra_fields: 180 fielddef.extend(extra_fields) 181 csvtable = Table(filename, fielddef, dbf_type=dbf_type) 182 for record in mtable: 183 csvtable.append(record.scatter_fields()) 184 return csvtable 185 return mtable
186 -def get_fields(table):
187 "returns the list of field names of a table" 188 table = Table(table) 189 return table.field_names
190 -def info(table):
191 "prints table info" 192 table = Table(table) 193 print str(table)
194 -def rename_field(table, oldfield, newfield):
195 "renames a field in a table" 196 table = Table(table) 197 try: 198 table.rename_field(oldfield, newfield) 199 finally: 200 table.close()
201 -def structure(table, field=None):
202 "returns the definition of a field (or all fields)" 203 table = Table(table) 204 return table.structure(field)
205 -def hex_dump(records):
206 "just what it says ;)" 207 for index,dummy in enumerate(records): 208 chars = dummy._data 209 print "%2d: " % index, 210 for char in chars[1:]: 211 print " %2x " % ord(char), 212 print
213