Class: ImExport::Import

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

Class Method Summary collapse

Class Method Details

.from_file(file_name, options = {}) ⇒ Object 



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# File 'lib/imexport.rb', line 8

def self.from_file(file_name, options = {})
  if options[:class_name] =~ /[^a-zA-Z\:]+/
    raise "#{options[:class_name]} doesn't look like a class name"
  end
  
  ## e.g. :seminar => "seminar" => "Seminar" => Seminar
  model = eval(options[:class_name].to_s.classify)
  
  ## used to check for an existing record. so we do update_attributes()
  # instead of save() in that case
  #
  # Example:
  # :find_by => :title # model.find_by_title
  @@find_by_attribute = options[:find_by].to_s
  
  ## helps to distinguish between real columns and column content
  # could be something like "COLUMN_"
  columns_prefix = options[:db_columns_prefix].to_s
  
  ## for each line, this is how we check for a new column or cont.
  # from the previous line
  scan_regexp = Regexp.new("^\\s*#{columns_prefix}(\\w+)\\: (.*)")
  
  ## table columns --> model attributes mapping
  # if an attribute is not specified and present as a column,
  # it'll try figure it out:
  # { 'title' => :title } - works w/o expicit mapping
  attr_map = options[:map] || {}
  
  ## verbose option
  # is a Proc type. Should return true or false.
  # If true a warning message outputs to stderr in case !model.valid?
  # 
  # Example:
  # verbose => Proc.new { |seminar| seminar.date.future? }
  #
  # verbose => nil or not specifying this options at all makes it silent
  @@verbose = options.include?(:verbose) ? options[:verbose] : true # default is verbose
  
  ## Read the file
  # we assume it's been created with vertial columns layout (mysql -E ...)
  model_inst = nil
  IO.foreach(file_name) do |line|
    ## mysql -E ... does this:
    # ********* 1. row **********
    # column: value
    # another_column: value
    # ... 
    # ********* 2. row **********
    unless (line =~ /^\*+ \d+\. row \*+$/).nil?
      ## We've got a new row
      # save or update previously created object ...
      unless block_given?
        save_or_update(model_inst) if model_inst
      else
        ## or pass it to a block
        # in this case we don't do any validations
        yield(model_inst)
      end 
      
      # ... then create a new one
      #$stderr.puts "\n###################################"
      model_inst = model.new
      @last_column_name = nil
      @last_column_content = nil
      next
    end
    
    ## Cont. of the same row.
    ## It's one table column at a time (or more lines).
    ## Parse it and add set the corresponding attribute in the model
    line.chomp!
    column = line.scan(scan_regexp)
    #$stderr.puts column.inspect
    
    unless column.size > 0
      ## this is a column continuation of the previous line
      @last_column_content << '<br/>' << line
      next
    end
    
    ## this is a new model attribute
    # set last attribute in the model if defined
    # we should have at least two items in the array
    column.flatten!
    @last_column_name = column.first
    @last_column_content = column[1].gsub(/\t+/, " ").strip.gsub(/^\n+$/, "").gsub(/\n+/, "<br/>")
    
    # in column-to-model map
    if attr_map.include?(@last_column_name)
      mattr = attr_map[@last_column_name]
      case
        when mattr.kind_of?(Symbol)
          model_inst.send("#{mattr.to_s}=", @last_column_content)
        when mattr.kind_of?(Proc)
          mattr.call(@last_column_content, model_inst)
        when mattr.kind_of?(Hash)
          model_inst.send("#{mattr.keys.first}=", mattr.values.first.call(@last_column_content))
        else
          $stderr.puts "WARNING: don't know how to handle #{mattr.inspect}"
      end
      
    # simple auto-mapping  
    elsif model_inst.respond_to?("#{@last_column_name}=")
      model_inst.send("#{@last_column_name}=", @last_column_content)
      
    # otherwise we don't know how to do it
    else
      $stderr.puts "WARNING: don't know how to set :#{@last_column_name}"
    end
  end # IO.foreach
  
  # TODO: more DRY
  # save the last one
  unless block_given?
    save_or_update(model_inst) if model_inst
  else
    ## or pass it to a block
    # in this case we don't do any validations
    yield(model_inst)
  end
end

.save_or_update(model) ⇒ Object 



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# File 'lib/imexport.rb', line 131

def self.save_or_update(model)
  # save it if valid or say an error
  if !model.nil? and model.valid?
    if (s = model.class.send("find_by_#{@@find_by_attribute}", model.read_attribute(@@find_by_attribute)))
      s.update_attributes(model.attributes.reject{|k,v| v.nil?})
    else
      model.save
    end
  elsif (@@verbose.kind_of?(Proc) ? @@verbose.call(model) : @@verbose)
    $stderr.puts "\n>>> ERRORS while storing #{model.class.to_s}: #{model.errors.full_messages.join('; ')}\n#{model.inspect}" unless model.nil?
  end
end