Class: DrNicMagicModels::Schema

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

Overview

ONE Schema per namespace module Person, Company, etc share the Object namespace module, ie. ::Person, ::Company Blog::Post, Blog::Comment, share the Blog namespace module

Constant Summary collapse

ReservedTables =

all in lower case please

[:schema_info, :sessions]

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(modul) ⇒ Schema

Returns a new instance of Schema.



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# File 'lib/dr_nic_magic_models/schema.rb', line 9

def initialize(modul)
  @modul = modul
  @table_name_prefix = modul.instance_variable_get("@table_name_prefix") rescue ''
  logger.info "Create Schema for #{@modul}, table_name_prefix '#{@table_name_prefix}'"
end

Instance Attribute Details

#modul ⇒ Object (readonly)

Returns the value of attribute modul.



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# File 'lib/dr_nic_magic_models/schema.rb', line 7

def modul
  @modul
end

Instance Method Details

#add_has_some_belongs_to(belongs_to_klass, belongs_to_fk, has_some_klass) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 176

def add_has_some_belongs_to(belongs_to_klass, belongs_to_fk, has_some_klass)
  
  logger.debug "Trying to add a #{belongs_to_klass} belongs_to #{has_some_klass}..."
  
  # so this is a belongs_to & has_some style relationship...
  # is it a has_many, or a has_one? Well, let's assume a has_one has a unique index on the column please... good db design, haha!      
  unique = belongs_to_klass.get_unique_index_columns.include?(belongs_to_fk)
  belongs_to_name = belongs_to_fk.sub(/_id$/, '').to_sym
  
  logger.debug "\n*** #{belongs_to_klass}.send 'belongs_to', #{belongs_to_name}, :class_name => #{has_some_klass}, :foreign_key => #{belongs_to_fk}\n"
  belongs_to_klass.send(:belongs_to, belongs_to_name, :class_name => has_some_klass.to_s, :foreign_key => belongs_to_fk.to_sym)
  
  # work out if we need a prefix
  has_some_name = (
   (unique ? belongs_to_klass.table_name.singularize : belongs_to_klass.table_name) + 
   (belongs_to_name.to_s == has_some_klass.table_name.singularize ? "" : "_as_"+belongs_to_name.to_s)
  ).downcase.to_sym
  method = unique ? :has_one : :has_many          
  logger.debug "\n*** #{has_some_klass}.send(#{method}, #{has_some_name}, :class_name => #{belongs_to_klass.to_s}, :foreign_key => #{belongs_to_fk.to_sym})\n\n"
  has_some_klass.send(method, has_some_name, :class_name => belongs_to_klass.to_s, :foreign_key => belongs_to_fk.to_sym)
  
  return { :method => method, :belongs_to_name => belongs_to_name, :has_some_name => has_some_name, :has_some_class => has_some_klass  }
  
end

#fks_on_table(table_name) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 46

def fks_on_table(table_name)
  load_schema if @models.nil?
  @fks_by_table[table_name.to_s] || []
end

#inflector ⇒ Object

Need to store models etc per-module, not in @ @models



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# File 'lib/dr_nic_magic_models/schema.rb', line 19

def inflector
  @inflector ||= Inflector.new
end

#is_link_table?(table_name) ⇒ Boolean

active record only support 2 column link tables, otherwise use a model table, has_many and through

Returns:

  • (Boolean) 


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# File 'lib/dr_nic_magic_models/schema.rb', line 52

def is_link_table?(table_name)
  load_schema if @models.nil?      
  return @link_tables[table_name] if ! @link_tables[table_name].nil?
  column_names = @conn.columns(table_name).map{|x| x.name }
  @link_tables[table_name] = ! column_names.include?("id") && column_names.length == 2 && column_names.select { |x| x =~ /_id$/ } == column_names
  return @link_tables[table_name]
end

#link_tables_for_class(klass) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 60

def link_tables_for_class(klass)
  load_schema if @models.nil?      
end

#load_schema(preload = false) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 64

def load_schema(preload = false)
  return if !@models.nil?
  
  @superklass ||= ActiveRecord::Base
  raise "No database connection" if !(@conn = @superklass.connection)
  
  @models = ModelHash.new
  @tables = Hash.new
  @fks_by_table = Hash.new   
  @link_tables = Hash.new
  
  @table_names = @conn.tables
  @table_names = @table_names.grep(/^#{@table_name_prefix}/) if @table_name_prefix
  @table_names = @table_names.sort
  
  logger.info "For #{modul} tables are #{@table_names.inspect}"
  
  # Work out which tables are in the model and which aren't
  @table_names.each do |table_name|
    
    # deal with reserved tables & link_tables && other stray id-less tables
    #key = 'id'
    #case ActiveRecord::Base.primary_key_prefix_type
    #  when :table_name
    #    key = Inflector.foreign_key(table_name, false)
    #  when :table_name_with_underscore
    #    key = Inflector.foreign_key(table_name)
    #end
    #next if ReservedTables.include?(table_name.downcase.to_sym) || 
    #        is_link_table?(table_name) || 
    #        ! @conn.columns(table_name).map{ |x| x.name}.include?(key)
    
    table_name_clean = table_name.gsub(/^#{@table_name_prefix}/,'')
    
    # a model table then...
    model_class_name = inflector.class_name(table_name_clean)
    
    logger.debug "Got a model table: #{table_name} => class #{model_class_name}"
    
    @models[model_class_name] = table_name
    @tables[table_name] = model_class_name
    
    if preload
      # create by MAGIC!
      klass = model_class_name.constantize
      
      # Process FKs?
      if @conn.supports_fetch_foreign_keys?          
        
        tables.each do |table_name| 
          logger.debug "Getting FKs for #{table_name}"
          @fks_by_table[table_name] = Array.new                        
          @conn.foreign_key_constraints(table_name).each do |fk| 
            logger.debug "Got one: #{fk}"
            @fks_by_table[table_name].push(fk)              
          end # do each fk
          
        end # each table
      end         
      
      # Try to work out our link tables now...
      @models.keys.sort.each{|klass| process_table(@models[klass.to_s])}
      @link_tables.keys.sort.each{|table_name| process_link_table(table_name) if @link_tables[table_name]}        
    end  
  end
  
end

#logger ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 27

def logger
  @logger ||= DrNicMagicModels::Logger
end

#models ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 31

def models
  load_schema if @models.nil?
  @models
end

#process_link_table(table_name) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 201

def process_link_table(table_name)
  
  logger.debug "Processing link table #{table_name}"
  
  classes_map = Hash.new
  column_names = @conn.columns(table_name).map{ |x| x.name}
  
  # use foreign keys first
  fks_on_table(table_name).each do |fk|
    logger.debug "Processing fk: #{fk}"
    klass = Inflector.classify(fk.reference_table).constantize rescue logger.debug("Cannot find model #{class_name} for table #{fk.reference_table}") && return
    classes_map[fk.foreign_key] = klass              
  end
  
  logger.debug "Got #{classes_map.keys.length} references from FKs"
  
  if classes_map.keys.length < 2
    
    #Fall back on good ol _id recognition
    
    column_names.each do |column_name|
      
      # check we haven't processed by fks already
      next if ! classes_map[column_name].nil? 
      referenced_table = column_name.sub(/_id$/, '')
      
      begin            
        klass = Inflector.classify(referenced_table).constantize                              
        # fall back on FKs here
        if ! klass.nil?               
          classes_map[column_name] = klass               
        end
      rescue
      end   
    end
  end
  
  # not detected the link table?
  logger.debug "Got #{classes_map.keys.length} references"
  logger.debug "Cannot detect both tables referenced in link table" && return if classes_map.keys.length != 2
  
  logger.debug "Adding habtm relationship"
  
  logger.debug "\n*** #{classes_map[column_names[0]]}.send 'has_and_belongs_to_many', #{column_names[1].sub(/_id$/,'').pluralize.to_sym}, :class_name => #{classes_map[column_names[1]].to_s}, :join_table => #{table_name.to_sym}\n"
  logger.debug "\n*** #{classes_map[column_names[1]]}.send 'has_and_belongs_to_many', #{column_names[0].sub(/_id$/,'').pluralize.to_sym}, :class_name => #{classes_map[column_names[0]].to_s}, :join_table => #{table_name.to_sym}\n\n"        
  
  classes_map[column_names[0]].send 'has_and_belongs_to_many', column_names[1].sub(/_id$/,'').pluralize.to_sym, :class_name => classes_map[column_names[1]].to_s, :join_table => table_name.to_sym
  classes_map[column_names[1]].send 'has_and_belongs_to_many', column_names[0].sub(/_id$/,'').pluralize.to_sym, :class_name => classes_map[column_names[0]].to_s, :join_table => table_name.to_sym
  
end

#process_table(table_name) ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 132

def process_table(table_name)
  
  logger.debug "Processing model table #{table_name}"
  
  # ok, so let's look at the foreign keys on the table...
  belongs_to_klass = @tables[table_name].constantize rescue return

  processed_columns = Hash.new
  
  fks_on_table(table_name).each do |fk|        
    logger.debug "Found FK column by suffix _id [#{fk.foreign_key}]"            
    has_some_klass = Inflector.classify(fk.reference_table).constantize rescue next
  processed_columns[fk.foreign_key] = { :has_some_klass => has_some_klass }
    processed_columns[fk.foreign_key].merge! add_has_some_belongs_to(belongs_to_klass, fk.foreign_key, has_some_klass) rescue next          
  end    
  
  column_names = @conn.columns(table_name).map{ |x| x.name}
  column_names.each do |column_name|        
    next if not column_name =~ /_id$/
    logger.debug "Found FK column by suffix _id [#{column_name}]"
    if processed_columns.key?(column_name)
      logger.debug "Skipping, already processed"
      next
    end
    has_some_klass = Inflector.classify(column_name.sub(/_id$/,"")).constantize rescue next
  processed_columns[column_name] = { :has_some_klass => has_some_klass }        
    processed_columns[column_name].merge! add_has_some_belongs_to(belongs_to_klass, column_name, has_some_klass) rescue next
  end
  
  #TODO: what if same classes in table?
  
  # is this a link table with attributes? (has_many through?)
  return if processed_columns.keys.length < 2
  
  processed_columns.keys.each do |key1|
    processed_columns.keys.each do |key2|
      next if key1 == key2
      logger.debug "\n*** #{processed_columns[key1][:has_some_class]}.send 'has_many', #{processed_columns[key2][:belongs_to_name].to_s.pluralize.to_sym}, :through => #{processed_columns[key2][:has_some_name]}\n\n"
      processed_columns[key1][:has_some_class].send 'has_many', processed_columns[key2][:belongs_to_name].to_s.pluralize.to_sym, :through => processed_columns[key2][:has_some_name].to_sym
    end              
  end
  
end

#table_names ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 41

def table_names
  load_schema if @table_names.nil?
  @table_names
end

#tables ⇒ Object 



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# File 'lib/dr_nic_magic_models/schema.rb', line 36

def tables
  load_schema if @tables.nil?
  @tables
end