Class: NERA::Database

Inherits:
Object
  • Object
show all
Includes:
Observable
Defined in:
lib/nera/nera_database.rb

Constant Summary collapse

VALUE_CLASSES =

search a data file in this order classes of values

[ String, Symbol, Integer, Float, Date, DateTime, TrueClass, FalseClass, NilClass ]

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path_to_file, notify_observer_arg = nil) ⇒ Database 



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# File 'lib/nera/nera_database.rb', line 81

def initialize( path_to_file, notify_observer_arg = nil )
  @filename = path_to_file
  @in_transaction = nil
  @notify_observer_arg = notify_observer_arg
  @yml_path = nil
  unless File.exist?(@filename)
    raise "No such database : #{@filename}"
  end
end

Class Method Details

.create_table(filename) ⇒ Object 



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# File 'lib/nera/nera_database.rb', line 141

def self.create_table( filename)
  if File.exists?( filename)
    $stderr.puts "Database #{filename} already exists."
    return nil
  end
  db = PStore.new( filename)
  db.transaction(false) do
    db[:max_id] = 0
  end
  return true
end

Instance Method Details

#add(new_rec) ⇒ Object 



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# File 'lib/nera/nera_database.rb', line 155

def add( new_rec )
  unless valid_as_a_record?( new_rec)
    raise ArgumentError, "This record is not valid."
  end
  new_id = nil
  transaction do
    new_id = @pstore[:max_id] + 1
    new_rec[:id] = new_id
    @pstore[:max_id] = new_id
    @pstore[new_id] = new_rec
    changed
  end
  return new_id
end

#destroy(ids) ⇒ Object

  • destroy( id )

— destroy records — id may be an Integer, Array of Integers, Range — if the specified record is not found in the table, return nil.



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# File 'lib/nera/nera_database.rb', line 271

def destroy( ids)
  if ids.is_a?( Array)
    status = []
    transaction do
      ids.each do |id|
        status << destroy( id)
      end
    end
    return status
  elsif ids.is_a?( Range)
    flag = nil
    transaction do
      id_array = @pstore.roots.find_all do |id|
        ids.include?(id)
      end
      flag = destroy( id_array)
    end
    flag = flag.find do |f| f end
    return flag
  elsif ids.is_a?( Integer)
    stat = nil
    transaction do
      stat = @pstore.delete(ids)
      changed
    end
    return stat
  else
    raise ArgumentError, "argument must be specified by Integer, Array of Integer, or Range. : #{ids.class}"
  end
  return true
end

#find_all ⇒ Object

— find all — usage: find_all { ..(condition).. }



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# File 'lib/nera/nera_database.rb', line 224

def find_all
  matched = []
  readonly_transaction do
    all_ids = @pstore.roots
    all_ids.delete( :max_id)
    all_ids.each do |id|
      if yield @pstore[id].dup
        matched << @pstore[id]
      end
    end
  end
  matched.sort! do |rec1,rec2|
    rec1[:id] <=> rec2[:id]
  end
  matched = nil if matched.size == 0
  return matched
end

#find_by_id(ids) ⇒ Object

— find methods ————————–



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# File 'lib/nera/nera_database.rb', line 186

def find_by_id( ids)
  if ids.is_a?(Integer)
    readonly_transaction do
      return @pstore[ids]
    end
  elsif ids.is_a?(Array)
    found = []
    readonly_transaction do
      # find all ----
      ids.each do |id|
        found << @pstore[id]
      end
      return found
    end
  elsif ids.is_a?(Range)
    found = []
    readonly_transaction do
      matched_ids = @pstore.roots.find_all do |id|
        ids.include?(id)
      end
      return nil unless matched_ids
      matched_ids.sort! do |id1,id2|
        id1 <=> id2
      end
      matched_ids.each do |id|
        found << @pstore[id]
      end
      found = nil if found.size == 0
      return found
    end
  else 
    raise ArgumentError, "Argument of the find method must be Integer, Array or Range. : #{ids.class}"
  end
end

#set_yaml_file(yml_path) ⇒ Object 



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# File 'lib/nera/nera_database.rb', line 92

def set_yaml_file( yml_path)
  @yml_path = yml_path.to_s
end

#transaction ⇒ Object 



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# File 'lib/nera/nera_database.rb', line 97

def transaction
  if @in_transaction     # nothing happens when the process is already in transaction
    yield
    return nil
  end
  @pstore = PStore.new(@filename)
  @pstore.transaction( false) do
    begin
      @in_transaction = true
      yield
      if @notify_observer_arg
        notify_observers( @notify_observer_arg)
      else
        notify_observers
      end
      if @yml_path
        File.open( @yml_path,'w') do |io|
          l = find_all do |r| true end
          YAML.dump( l, io)
          io.flush
        end
      end
    ensure
      @in_transaction = false
      nil
    end
  end
end

#update(rec) ⇒ Object

— update method —

  • update( rec )

— update a record — ex. db.update( :key1=>‘updated’, :key2=>DateTime.now ) — returns nil if the record of the specified ‘id’ does not exist.



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# File 'lib/nera/nera_database.rb', line 248

def update( rec)
  unless valid_as_a_record?( rec)
    $stderr.puts "This record is not valid."
    return nil
  end
  id_to_update = rec[:id]
  flag = nil
  transaction do
    unless @pstore.root?( id_to_update)
      return nil
    end
    @pstore[id_to_update] = rec
    flag = true
    changed
  end
  return flag
end