Class: DBF::Table

Inherits:

Object

• Object
• DBF::Table

show all

Includes:

Enumerable

Defined in:

lib/dbf/table.rb,
lib/dbf/table/encodings.rb

Overview

Constant Summary

DBF_HEADER_SIZE =

32

VERSIONS =

{
  "02" => "FoxBase",
  "03" => "dBase III without memo file",
  "04" => "dBase IV without memo file",
  "05" => "dBase V without memo file",
  "07" => "Visual Objects 1.x",
  "30" => "Visual FoxPro",
  "31" => "Visual FoxPro with AutoIncrement field",
  "43" => "dBASE IV SQL table files, no memo",
  "63" => "dBASE IV SQL system files, no memo",
  "7b" => "dBase IV with memo file",
  "83" => "dBase III with memo file",
  "87" => "Visual Objects 1.x with memo file",
  "8b" => "dBase IV with memo file",
  "8e" => "dBase IV with SQL table",
  "cb" => "dBASE IV SQL table files, with memo",
  "f5" => "FoxPro with memo file",
  "fb" => "FoxPro without memo file"
}

FOXPRO_VERSIONS =

{
  "30" => "Visual FoxPro",
  "31" => "Visual FoxPro with AutoIncrement field",
  "f5" => "FoxPro with memo file",
  "fb" => "FoxPro without memo file"
}

ENCODINGS =

inspired by trac.osgeo.org/gdal/ticket/2864

{
  "01" => "cp437",       # U.S. MS–DOS
  "02" => "cp850",       # International MS–DOS
  "03" => "cp1252",      # Windows ANSI
  "08" => "cp865",       # Danish OEM
  "09" => "cp437",       # Dutch OEM
  "0a" => "cp850",       # Dutch OEM*
  "0b" => "cp437",       # Finnish OEM
  "0d" => "cp437",       # French OEM
  "0e" => "cp850",       # French OEM*
  "0f" => "cp437",       # German OEM
  "10" => "cp850",       # German OEM*
  "11" => "cp437",       # Italian OEM
  "12" => "cp850",       # Italian OEM*
  "13" => "cp932",       # Japanese Shift-JIS
  "14" => "cp850",       # Spanish OEM*
  "15" => "cp437",       # Swedish OEM
  "16" => "cp850",       # Swedish OEM*
  "17" => "cp865",       # Norwegian OEM
  "18" => "cp437",       # Spanish OEM
  "19" => "cp437",       # English OEM (Britain)
  "1a" => "cp850",       # English OEM (Britain)*
  "1b" => "cp437",       # English OEM (U.S.)
  "1c" => "cp863",       # French OEM (Canada)
  "1d" => "cp850",       # French OEM*
  "1f" => "cp852",       # Czech OEM
  "22" => "cp852",       # Hungarian OEM
  "23" => "cp852",       # Polish OEM
  "24" => "cp860",       # Portuguese OEM
  "25" => "cp850",       # Portuguese OEM*
  "26" => "cp866",       # Russian OEM
  "37" => "cp850",       # English OEM (U.S.)*
  "40" => "cp852",       # Romanian OEM
  "4d" => "cp936",       # Chinese GBK (PRC)
  "4e" => "cp949",       # Korean (ANSI/OEM)
  "4f" => "cp950",       # Chinese Big5 (Taiwan)
  "50" => "cp874",       # Thai (ANSI/OEM)
  "57" => "cp1252",      # ANSI
  "58" => "cp1252",      # Western European ANSI
  "59" => "cp1252",      # Spanish ANSI
  "64" => "cp852",       # Eastern European MS–DOS
  "65" => "cp866",       # Russian MS–DOS
  "66" => "cp865",       # Nordic MS–DOS
  "67" => "cp861",       # Icelandic MS–DOS
  "6a" => "cp737",       # Greek MS–DOS (437G)
  "6b" => "cp857",       # Turkish MS–DOS
  "6c" => "cp863",       # French–Canadian MS–DOS
  "78" => "cp950",       # Taiwan Big 5
  "79" => "cp949",       # Hangul (Wansung)
  "7a" => "cp936",       # PRC GBK
  "7b" => "cp932",       # Japanese Shift-JIS
  "7c" => "cp874",       # Thai Windows/MS–DOS
  "86" => "cp737",       # Greek OEM
  "87" => "cp852",       # Slovenian OEM
  "88" => "cp857",       # Turkish OEM
  "c8" => "cp1250",      # Eastern European Windows
  "c9" => "cp1251",      # Russian Windows
  "ca" => "cp1254",      # Turkish Windows
  "cb" => "cp1253",      # Greek Windows
  "cc" => "cp1257",      # Baltic Windows
}

Instance Attribute Summary (collapse)

• - (Object) encoding

  Internal dBase version number Total number of records Source encoding (for ex. :cp1251).

• - (Object) record_count readonly

  Returns the value of attribute record_count.

• - (Object) version readonly

  Returns the value of attribute version.

Instance Method Summary (collapse)

• - (TrueClass, FalseClass) close

  Closes the table and memo file.

• - (TrueClass, FalseClass) closed?
• - (Object) columns

  Retrieves column information from the database.

• - (Object) each {|nil, DBF::Record| ... }

  Calls block once for each record in the table.

• - (Object) filename

  String.

• - (Object) find(command, options = {}) {|optional, DBF::Record, NilClass| ... }

  Find records using a simple ActiveRecord-like syntax.

• - (Boolean) foxpro?
• - (TrueClass, FalseClass) has_memo_file?
• - (Table) initialize(data, memo = nil, encoding = nil) constructor

  Opens a DBF::Table Examples:.

• - (DBF::Record, NilClass) record(index) (also: #row)

  Retrieve a record by index number.

• - (String) schema

  Generate an ActiveRecord::Schema.

• - (Boolean) supports_encoding?
• - (Boolean) supports_iconv?
• - (Object) to_csv(path = nil)

  Dumps all records to a CSV file.

• - (String) version_description

  Human readable version description.

# working with a file stored on the filesystem
table = DBF::Table.new 'data.dbf'

# working with a misnamed memo file
table = DBF::Table.new 'data.dbf', 'memo.dbt'

# working with a dbf in memory
table = DBF::Table.new StringIO.new(dbf_data)

# working with a dbf and memo in memory
table = DBF::Table.new StringIO.new(dbf_data), StringIO.new(memo_data)

# working with a dbf overriding specified in the dbf encoding
table = DBF::Table.new 'data.dbf', nil, 'cp437'
table = DBF::Table.new 'data.dbf', 'memo.dbt', Encoding::US_ASCII

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# File 'lib/dbf/table.rb', line 62

def initialize(data, memo = nil, encoding = nil)
  @data = open_data(data)
  @version, @record_count, @header_length, @record_length, @encoding_key, @encoding = get_header_info
  @encoding = encoding if encoding
  @memo = open_memo(data, memo)
end

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# File 'lib/dbf/table.rb', line 39

def encoding
  @encoding
end

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# File 'lib/dbf/table.rb', line 38

def record_count
  @record_count
end

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# File 'lib/dbf/table.rb', line 37

def version
  @version
end

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# File 'lib/dbf/table.rb', line 77

def close
  @data.close
  @memo && @memo.close
end

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# File 'lib/dbf/table.rb', line 83

def closed?
  if @memo
    @data.closed? && @memo.closed?
  else
    @data.closed?
  end
end

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# File 'lib/dbf/table.rb', line 205

def columns
  @columns ||= begin
    @data.seek(DBF_HEADER_SIZE)
    columns = []
    while !["\0", "\r"].include?(first_byte = @data.read(1))
      column_data = first_byte + @data.read(31)
      name, type, length, decimal = column_data.unpack('a10 x a x4 C2')
      if length > 0
        columns << column_class.new(name.strip, type, length, decimal, version, @encoding)
      end
    end
    columns
  end
end

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# File 'lib/dbf/table.rb', line 100

def each
  @record_count.times {|i| yield record(i)}
end

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# File 'lib/dbf/table.rb', line 92

def filename
  File.basename @data.path
end

table = DBF::Table.new 'mydata.dbf'

# Find record number 5
table.find(5)

# Find all records for Keith Morrison
table.find :all, :first_name => "Keith", :last_name => "Morrison"

# Find first record
table.find :first, :first_name => "Keith"

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# File 'lib/dbf/table.rb', line 191

def find(command, options = {}, &block)
  case command
  when Fixnum
    record(command)
  when Array
    command.map {|i| record(i)}
  when :all
    find_all(options, &block)
  when :first
    find_first(options)
  end
end

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# File 'lib/dbf/table.rb', line 231

def foxpro?
  FOXPRO_VERSIONS.keys.include? @version
end

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# File 'lib/dbf/table.rb', line 70

def has_memo_file?
  !!@memo
end

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# File 'lib/dbf/table.rb', line 110

def record(index)
  seek(index * @record_length)
  if !deleted_record?
    DBF::Record.new(@data.read(@record_length), columns, version, @memo)
  end
end

create_table "mydata" do |t|
  t.column :name, :string, :limit => 30
  t.column :last_update, :datetime
  t.column :is_active, :boolean
  t.column :age, :integer
  t.column :notes, :text
end

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# File 'lib/dbf/table.rb', line 147

def schema
  s = "ActiveRecord::Schema.define do\n"
  s << "  create_table \"#{File.basename(@data.path, ".*")}\" do |t|\n"
  columns.each do |column|
    s << "    t.column #{column.schema_definition}"
  end
  s << "  end\nend"
  s
end

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# File 'lib/dbf/table.rb', line 220

def supports_encoding?
  String.new.respond_to?(:encoding)
end

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# File 'lib/dbf/table.rb', line 224

def supports_iconv?
  require 'iconv'
  true
rescue
  false
end

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# File 'lib/dbf/table.rb', line 161

def to_csv(path = nil)
  csv = csv_class.new((path ? File.open(path, 'w') : $stdout), :force_quotes => true)
  csv << columns.map {|c| c.name}
  each {|record| csv << record.to_a}
end

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# File 'lib/dbf/table.rb', line 122

def version_description
  VERSIONS[version]
end