Class: Kladr::DBF::Table

Inherits:
Object
  • Object
show all
Defined in:
lib/dbf/dbf/table.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename, options = {}) ⇒ Table

Initialize a new DBF::Reader. Example:

reader = DBF::Reader.new 'data.dbf'



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# File 'lib/dbf/dbf/table.rb', line 32

def initialize(filename, options = {})
  @options = {:in_memory => true, :accessors => true}.merge(options)

  @in_memory = @options[:in_memory]
  @accessors = @options[:accessors]
  @data = File.open(filename, 'rb')
  @memo = open_memo(filename)
  reload!
end

Instance Attribute Details

#column_count ⇒ Object (readonly)

The total number of columns (columns)



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# File 'lib/dbf/dbf/table.rb', line 6

def column_count
  @column_count
end

#columns ⇒ Object (readonly)

An array of DBF::Column records



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# File 'lib/dbf/dbf/table.rb', line 9

def columns
  @columns
end

#data ⇒ Object (readonly)

Returns the value of attribute data.



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# File 'lib/dbf/dbf/table.rb', line 26

def data
  @data
end

#last_updated ⇒ Object (readonly)

Last updated datetime



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# File 'lib/dbf/dbf/table.rb', line 15

def last_updated
  @last_updated
end

#memo ⇒ Object (readonly)

Returns the value of attribute memo.



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# File 'lib/dbf/dbf/table.rb', line 27

def memo
  @memo
end

#memo_block_size ⇒ Object (readonly)

The block size for memo records



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# File 'lib/dbf/dbf/table.rb', line 21

def memo_block_size
  @memo_block_size
end

#memo_file_format ⇒ Object (readonly)

Either :fpt or :dpt



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# File 'lib/dbf/dbf/table.rb', line 18

def memo_file_format
  @memo_file_format
end

#options ⇒ Object (readonly)

The options that were used when initializing DBF::Table. This is a Hash.



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# File 'lib/dbf/dbf/table.rb', line 24

def options
  @options
end

#version ⇒ Object (readonly)

Internal dBase version number



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# File 'lib/dbf/dbf/table.rb', line 12

def version
  @version
end

Instance Method Details

#column(column_name) ⇒ Object

Returns an instance of DBF::Column for column_name. column_name can be a symbol or a string.



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# File 'lib/dbf/dbf/table.rb', line 63

def column(column_name)
  @columns.detect {|f| f.name == column_name.to_s}
end

#find(command, options = {}) ⇒ Object

Find records using a simple ActiveRecord-like syntax.

Examples:

reader = DBF::Reader.new 'mydata.dbf'

# Find record number 5
reader.find(5)

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

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

The command can be an id, :all, or :first. options is optional and, if specified, should be a hash where the keys correspond to column names in the database. The values will be matched exactly with the value in the database. If you specify more than one key, all values must match in order for the record to be returned. The equivalent SQL would be “WHERE key1 = ‘value1’ AND key2 = ‘value2’”.



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# File 'lib/dbf/dbf/table.rb', line 108

def find(command, options = {})
  results = options.empty? ? records : records.select {|record| all_values_match?(record, options)}

  case command
  when Fixnum
    record(command)
  when :all
    results
  when :first
    results.first
  end
end

#has_memo_file? ⇒ Boolean

Returns true if there is a corresponding memo file

Returns:

  • (Boolean) 


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# File 'lib/dbf/dbf/table.rb', line 52

def has_memo_file?
  @memo ? true : false
end

#record(index) ⇒ Object Also known as: row

Returns a DBF::Record (or nil if the record has been marked for deletion) for the record at index.



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# File 'lib/dbf/dbf/table.rb', line 80

def record(index)
  if options[:in_memory]
    records[index]
  else
    get_record_from_file(index)
  end
end

#record_count ⇒ Object

The total number of active records.



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# File 'lib/dbf/dbf/table.rb', line 57

def record_count
  @db_index.size
end

#records ⇒ Object Also known as: rows

An array of all the records contained in the database file. Each record is an instance of DBF::Record (or nil if the record is marked for deletion).



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# File 'lib/dbf/dbf/table.rb', line 69

def records
  if options[:in_memory]
    @records ||= get_all_records_from_file
  else
    get_all_records_from_file
  end
end

#reload! ⇒ Object

Reloads the database and memo files



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# File 'lib/dbf/dbf/table.rb', line 43

def reload!
  @records = nil
  get_header_info
  get_memo_header_info if @memo
  get_column_descriptors
  build_db_index
end

#schema(path = nil) ⇒ Object

Returns a database schema in the portable ActiveRecord::Schema format.

xBase data types are converted to generic types as follows:

  • Number columns are converted to :integer if there are no decimals, otherwise they are converted to :float

  • Date columns are converted to :datetime

  • Logical columns are converted to :boolean

  • Memo columns are converted to :text

  • Character columns are converted to :string and the :limit option is set to the length of the character column

Example:

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/dbf/table.rb', line 147

def schema(path = nil)
  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"

  if path
    File.open(path, 'w') {|f| f.puts(s)}
  else
    s
  end
end

#version_description ⇒ Object

Returns a description of the current database file.



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# File 'lib/dbf/dbf/table.rb', line 124

def version_description
  VERSION_DESCRIPTIONS[version]
end