Version 14 of tdbf

Updated 2012-08-09 20:40:36 by Googie

Description of the software

 What: tdbf
 Where: http://sqlitestudio.one.pl/tdbf/tdbf-0.3.tar.gz
 Description: [DBF] file reader/writter package.
 Dependencies: IncrTcl
 Licence: Tcl licence (BSD-like)
 Current version: 0.3
 Updated: 08/2012
 Author: Paweł Salawa (aka Googie).
 Contact: http://sqlitestudio.one.pl/index.rvt?act=contact

It depends on Itcl, but this is just for quick namespace creation bounded with handler command. It's easy to get rid of Itcl from the code, but I just prefer to use it.


Features

  • Written in pure-Tcl (with Itcl), so it's cross-platform,
  • Simple API (see below),
  • Reads and writes dbf memo (M, G, B, P types) fields,
  • Re-uses deleted records area for new inserted records,
  • Supports some unique features of FoxPro and Clipper variants.
  • Doesn't suppport dBASE 7, but it's in TODO.

Demos

Read all records and print them

package require tdbf 0.1
tdbf::dbf myDbf
myDbf open test1.dbf

puts "Columns: [myDbf getColumnNames]"
while {[set values [myDbf gets]] != ""} {
    puts $values
}

myDbf close

Read all records and print them - 2nd method

package require tdbf 0.1
tdbf::dbf myDbf
myDbf open test1.dbf

set columns [myDbf getColumnNames]
puts "Columns: $columns"
myDbf for value {
    foreach c $columns {
        puts -nonewline "$value($c) "
    }
    puts ""
}

myDbf close

Create dbf and put some data into it

This script will create dbf file, add 2 columns, then add 3 new records and then replace second record with new value.

package require tdbf 0.1
tdbf::dbf myDbf

file delete -force test2.dbf
myDbf open test2.dbf

myDbf addColumn "col1" "N" 3 ;# (numeric type, length = 3 digits)
myDbf addColumn "col2" "C" 20 ;# (character/text type, 20 characters)

for {set i 0} {$i < 3} {incr i} {
    myDbf insert [list $i "value $i"]
}

# Modify 2nd record
myDbf update 1 [list 5 "xyz"]

myDbf close

API

  • constructor {{errorHandler ""}}

The errorHandler code will be evaluated with literal error code appended (and optionally some other arguments). These errors are more like warnings. Dbf will still work but some limitations might be applied.

Possible values for reading file are:

DBT_DOESNT_EXISTWhen the .dbt file (memo table) doesn't exist or it's not readable, but the database type requires it to exists. It can be ignored, but in this case the referenced memo values will be returned as empty strings.

Possible values for writting file are:

DBT_READ_ONLYWhen .dbt file has read-only permissions or you cannot create the new .dbt file because of permissions.
COLUMN_EXISTSWhen trying to add column that already exist. Also column name is appended to error handler arguments. The addColumn will just skip this column.
RECORDS_EXISTWhen trying to add any column while there are already some records in DBF. Also column name is appended to error handler arguments. The addColumn will skip this column.
COLUMN_NAME_TOO_LONGWhen adding column with name longer than 10 characters (this is limited by DBF format). Column will still be added, but its name will be truncated to 10 characters.
VALUE_TOO_LONGMay happen for columns with type N and C (in future maybe in others too). It means that you tried to insert value to DBF field that is longer than defined field length. Remember, that length of type N (number) means length of string used to represent the number.
NO_RECORDS_WHILE_UPDATINGTried to update (with [dbf update]) while there's not a single record in DBF.
  • Static methods:
NameArgumentsDescription
dbf::julianDateToUnixTimevalueConverts value read from "T" or "@" type into unixtime format, but only if it's possible (i.e. the time is after start of a year 1970).
  • Object methods:
NameArgumentsDescription
openfileOpens DBF file. If will be closed automatically at object destruction. It also opens DBT file (memo table) if it exists. If file doesn't exists, it creates new DBF file. If necessary (during writting data) might create also a DBT file.
readfd ?memoFd?Reads DBF file from open channel. You can consider this method as a variant of [dbf open] accepting channels instead of file. Channel has to be readable (in any case) and writable (if you want to modify anything in file) and also switched to binary translation and non-blocking mode. Same requirements apply to memoFd. Channel for DBT (memo table) is optional.
closeCloses file that was open with [dbf open] or passed to [dbf read].
addColumnname type ?length? ?precision?Adds new column with given type (N, C, ...). Length is optional in most cases, except for types: N and C. Precision is always optional, but may be provided. Dbf cannot contain any records in order to add column.
insertvaluesInserts new data record into dbf. Number of elements in 'values' has to be the same as number of columns, otherwis error will be raised. Values have to be in same format as returned from [gets]. It inserts record in place of first record marked as deleted or if there's no deleted record, then it appends record to the end of DBF file.
deleteindexMarks record as deleted. Note that DBF records are not physically removed from file, they are just marked as deleted so they can be reused by [insert]. Use [vacuum] to force remove deleted records from file. Returns true on success or false on failure (index out of range).
updateindex values ?columnName?Updates all values of rercord with given index, or single column of that row if columnName is provided. See [seek] for index details. Returns true on success or false on failure (index out of range).
getAllDataReturns all records in format {{row1field1Value row1field2Value ...} {row2field1Value row2field2Value} ...}. Excludes deleted records.
forarrName bodyIterates through all records and puts each record values into array named arrName with column names as keys. For each record the body is executed with arrName prepared.
seekindexMoves reading/writting pointer at given position. Index is record order number in dbf (excluding deleted records), which is in range from 0 to [getDataCount]-1. Can be end-N. Returns true on success, false on failure (index out of range).
getsReturns record at current index and increments index. Remember to [seek] to proper record if you called any other method from this class before the [gets]. May return empty list if no data was available.
vacuumNot implemented yet.
getVersionReturns database file version in 2 hex characters format.
getVersionNameReturns human readable version description.
getLastModificationDateReturns last modification date in [clock seconds] format.
getColumnsReturns list of columns, where each column is a Tcl dict with keys: name, type, length, precision, indexed.
getColumnNamesReturns list of column names.
getDataCountReturns total number of records, excluding deleted records.
getRecordSizeReturns size of single record in bytes

Datatypes translation map

 #########################################################################
 # Datatype translation.
 #
 # Use this datatype translation map to learn what value formats
 # can you expect to be returned when reading DBF and use same formats
 # to pass the data to DBF while writting DBF.
 #########################################################################
 # DBF type               <-> Tcl value format
 #------------------------------------------------------------------------
 # C (characters)         <-> Tcl string
 # N (number/numeric)     <-> Tcl number (integer, float, double)
 # L (logical)            <-> Tcl boolean value or empty string (DBF allows it to be undefined)
 # I, + (integer)         <-> Tcl integer
 # D (date)               <-> Tcl string representing a date in format: "YYYYMMDD".
 # M, G (memo, general)   <-> Tcl string
 # 
 # F (float)              <-> Tcl float
 # B, P (binary, picture) <-> Binary data
 # O        (double)             <-> Tcl double
 # Y (currency)           <-> Tcl string representing huge decimal number (from
 #                            -922337203685477.5807 to +922337203685477.5807), which cannot be
 #                            represented as Tcl double.
 # V, X (varifield)       <-> Depending on field length and database type (FlagShip attribute):
 #                            2 (and flagship)  <-> Tcl integer
 #                            3                 <-> Same as for type "D".
 #                            4                 <-> Tcl integer
 #                            8 (and flagship)  <-> Tcl double
 #                            10 (and flagship) <-> This is special kind of DBF memo, so should
 #                                                  be a string, but this is not supported yet.
 #                            *                 <-> This also is special kind of DBF memo
 #                                                  and same thing as above applies here.
 #                           
 # T, @ (timestamp)       <-> List of {date time}, which are integers.
 #                            The date is the number of days since  01/01/4713 BC.
 #                            Time is: hours * 3600000 + minutes * 60000 + Seconds * 1000.
 #                            If the date at (or after) year 1970 you can use
 #                            dbf::julianDateToUnixTime to convert the value into format
 #                            usable for [clock] command.

ChangeLog

09.08.2012 - Version 0.3

  • Field type "T" is now read correctly.
  • Added julianDateToUnixTime function to convert jualian dates after 1970 to unixtime, which is more Tcl-like.
  • Fixed flushInitialHeader when creating new dbf file in any month except of 4th quater of the year - didn't work at all.

01.08.2012 - Version 0.2

  • Fixed reading of Visual FoxPro files.
  • "D" type is now read as string, not as unixtime, cause unixtime doesn't deal with dates before 1970.
  • "C" type is now trimmed from left side, so there are no extra white spaces before the actual value.
  • Added pkgIndex.tcl, making a complete Tcl package.

01.11.2011 - Version 0.1


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