Class: Tables

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

Overview

A class to handle parsing of table information from a datamodel XML file. Since relationships are defined by table IDs, a hash is constructed using table IDs.

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Tables

Returns a new instance of Tables.



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# File 'lib/dbmodel.rb', line 36

def initialize
  @table_hash = Hash.new
end

Instance Method Details

#add_relationship(r) ⇒ Object

Adds a relationship to the hash, where the relationship has source and destination table IDs definied by attributes SrcTable and DstTable. The RelationName attribute should be Rails-valid code. To-do: this could be made more robust where we trace the relationships through join tables and don’t require any model names in the relationship name.



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# File 'lib/dbmodel.rb', line 55

def add_relationship(r)
  src_table_id = r.attributes['SrcTable']
  src_table_name = @table_hash[src_table_id]['name']
  dest_table_id = r.attributes['DestTable']
  dest_table_name = @table_hash[dest_table_id]['name']
  
  relationship = r.attributes['RelationName']
  if relationship =~ /\s*habtm\s*:(\w+)/
    relationship = "  has_and_belongs_to_many :#{$1}"
  else
    # If we are inserting the other side of a relationship (non-habtm),
    # we need to mirror the relationship.
    # NOTE: in the DB model, links should be labeled 'has_one' or 'has_many'
    #       not 'belongs_to' since that label is ambiguous 1:1 or 1:n
    if relationship =~ /has_one/ or relationship =~ /has_many/
      @table_hash[dest_table_id]['relationships'] << '  belongs_to :' + src_table_name
    else relationship !~ /has_and_belongs_to_many/
      puts "error: relationships must be labeled 'has_one :x', 'has_many :x', 'habtm :x' or 'has_and_belongs_to_many :x'"
      return
    end
    relationship = '  ' + relationship
  end
  @table_hash[src_table_id]['relationships'] << relationship
end

#add_table(t) ⇒ Object

Adds a table to the hash, where the table is a REXML::Element with ID, Tablename, and Comments attributes



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# File 'lib/dbmodel.rb', line 42

def add_table(t)
  @table_hash[t.attributes['ID']] = {
    'name' => t.attributes['Tablename'],
    'comments' => t.attributes['Comments'],
    'relationships' => []
  }
end

#update_files(xmlfile) ⇒ Object

Updates the Rails app files to reflect what’s in the table hash. The location of the Rails app is gleaned from xmlfile, which is assumed to be in /db. If a model file doesn’t exist, a generate model or generate scaffold is called, depending on the presence of a [SCAFFOLD] tag in the table comments. Existing files are checked to make sure the relationship is defined. To-do: old relationships aren’t removed



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# File 'lib/dbmodel.rb', line 86

def update_files(xmlfile)
  @table_hash.each do |table_id, table|
    if not table['relationships'].empty?
      add_comments = false
      # If there's no model file, create one via generate scaffold script
      modelfile = File.dirname(xmlfile) + '\..\app\models\\' + table['name'].singularize + '.rb'
      if File.exist?(modelfile)
        puts "Model file (#{table['name'].singularize}) already exists. Skipping generation." if not $silent
      elsif table['comments'] =~ /\[\s*SCAFFOLD\s*(\s.*)*\s*\]/
        cmdline = ['scaffold', table['name'].singularize]
        if not $1.nil?
          $1.split(' ').collect { |arg| cmdline << arg }
        end
        cmdline << '-f'
        puts "Calling generator: #{cmdline.join(' ')}" if not $silent
        Rails::Generator::Scripts::Generate.new.run(cmdline) if not $dryrun
        add_comments = true
      elsif
        cmdline = ['model', table['name'].singularize, '-f']
        puts "Generating model for #{table['name'].singularize}" if not $silent
        Rails::Generator::Scripts::Generate.new.run(cmdline) if not $dryrun
        add_comments = true
      end

      update_file(modelfile, table_id, add_comments) if not $dryrun
    end
  end
end