Class: NoSE::Backend::PreparedUpdate

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

Overview

An update prepared with a backend which is ready to execute

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(statement, support_plans, steps) ⇒ PreparedUpdate

Returns a new instance of PreparedUpdate.



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# File 'lib/nose/backend.rb', line 402

def initialize(statement, support_plans, steps)
  @statement = statement
  @support_plans = support_plans
  @delete_step = steps.find do |step|
    step.is_a? Backend::DeleteStatementStep
  end
  @insert_step = steps.find do |step|
    step.is_a? Backend::InsertStatementStep
  end
end

Instance Attribute Details

#statement ⇒ Object (readonly)

Returns the value of attribute statement.



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# File 'lib/nose/backend.rb', line 400

def statement
  @statement
end

#steps ⇒ Object (readonly)

Returns the value of attribute steps.



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# File 'lib/nose/backend.rb', line 400

def steps
  @steps
end

Instance Method Details

#execute(update_settings, update_conditions) ⇒ void

This method returns an undefined value.

Execute the statement for the given set of conditions



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# File 'lib/nose/backend.rb', line 415

def execute(update_settings, update_conditions)
  # Execute all the support queries
  settings = initial_update_settings update_settings, update_conditions

  # Execute the support queries for this update
  support = support_results update_conditions

  # Perform the deletion
  @delete_step.process support unless support.empty? || @delete_step.nil?
  return if @insert_step.nil?

  # Get the fields which should be used from the original statement
  # If we didn't delete old entries, then we just need the primary key
  # attributes of the index, otherwise we need everything
  index = @insert_step.index
  include_fields = if @delete_step.nil?
                     index.hash_fields + index.order_fields
                   else
                     index.all_fields
                   end

  # Add fields from the original statement
  update_conditions.each_value do |condition|
    next unless include_fields.include? condition.field
    settings.merge! condition.field.id => condition.value
  end

  if support.empty?
    support = [settings]
  else
    support.each do |row|
      row.merge!(settings) { |_, value, _| value }
    end
  end

  # Stop if we have nothing to insert, otherwise insert
  return if support.empty?
  @insert_step.process support
end