Module: ViewModel

Defined in:
lib/view_model.rb,
lib/adapters/abstract_adapter.rb,
lib/adapters/postgresql_adapter.rb

Defined Under Namespace

Classes: AbstractAdapter, PostgreSQLAdapter

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.included(model) ⇒ Object 



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# File 'lib/view_model.rb', line 9

def self.included(model)   
  model.extend self 
end

Instance Method Details

#check_dependencies ⇒ Object

checks for dependent views



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# File 'lib/view_model.rb', line 34

def check_dependencies
  return if @view_dependencies == nil
  @view_dependencies.each do |dep|
    if dep.view_definition_set? == false
      raise "Cannot migrate: #{dep} does not have a view_definition set."
    end
  end 
end

#create_dependencies! ⇒ Object

create all dependent views



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# File 'lib/view_model.rb', line 52

def create_dependencies!
  return if @view_dependencies == nil
  @view_dependencies.each do |dep|
    dep.create_view!
  end 
end

#create_view! ⇒ Object

Create the model’s view according to it’s definition.



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# File 'lib/view_model.rb', line 80

def create_view!
  puts "creating view #{table_name}"
  sql = "CREATE OR REPLACE VIEW #{table_name} AS "
  sql << @view_definition
  execute(sql)
end

#drop_dependencies! ⇒ Object

drops all dependent views



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# File 'lib/view_model.rb', line 44

def drop_dependencies!
  return if @view_dependencies == nil
  @view_dependencies.each do |dep|
    dep.drop_view!
  end 
end

#drop_view! ⇒ Object

Drops a view if exists. note: “if exists” works only on Postgresql 8.2 or later. Older versions are not supported.



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# File 'lib/view_model.rb', line 89

def drop_view!
  puts "dropping view #{table_name}"
  execute("DROP VIEW if exists #{table_name}")
end

#execute(sql) ⇒ Object

shortcut for connection.execute(sql)



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# File 'lib/view_model.rb', line 19

def execute(sql)
  connection.execute(sql)
end

#get_adapter ⇒ Object

gets the adapter needed which has a custom method to get its dependencies



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# File 'lib/view_model.rb', line 24

def get_adapter
  adapter = connection.class.to_s.demodulize
  begin
   return ("ViewModel::"+adapter).constantize
  rescue
    raise "ViewModel: can't find adapter for ConnectionAdapter #{adapter}"
  end
end

#get_dependencies ⇒ Object

checks Postgresql relations for any view that uses current view.



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# File 'lib/view_model.rb', line 64

def get_dependencies
  @view_dependencies = get_adapter.get_dependencies(connection, table_name)
end

#migrate! ⇒ Object 



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# File 'lib/view_model.rb', line 68

def migrate!
  raise "Please provide a view_definition inside the model" if !view_definition_set?
  get_dependencies
  check_dependencies
  drop_dependencies!
  drop_view!
  create_view!
  create_dependencies!
  true
end

#view_definition(sql) ⇒ Object

sets the view_definition in the model



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# File 'lib/view_model.rb', line 14

def view_definition(sql)
  @view_definition = sql
end

#view_definition_set? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/view_model.rb', line 59

def view_definition_set?
  @view_definition != nil
end