Class: MR::ReadModel::SetExpression

Inherits:
Object
  • Object
show all
Defined in:
lib/mr/read_model/query_expression.rb

Constant Summary collapse

OPERATOR_SQL = 
{
  :union         => 'UNION'.freeze,
  :union_all     => 'UNION ALL'.freeze,
  :intersect     => 'INTERSECT'.freeze,
  :intersect_all => 'INTERSECT ALL'.freeze,
  :except        => 'EXCEPT'.freeze,
  :except_all    => 'EXCEPT ALL'.freeze
}.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(operator, &block) ⇒ SetExpression

Returns a new instance of SetExpression.

Raises:

  • (ArgumentError) 


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# File 'lib/mr/read_model/query_expression.rb', line 152

def initialize(operator, &block)
  raise ArgumentError, "a block must be provided" unless block
  @operator_sql     = OPERATOR_SQL[operator]
  @read_model_block = block
end

Instance Attribute Details

#operator_sql ⇒ Object (readonly)

Returns the value of attribute operator_sql.



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# File 'lib/mr/read_model/query_expression.rb', line 150

def operator_sql
  @operator_sql
end

#read_model_block ⇒ Object (readonly)

Returns the value of attribute read_model_block.



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# File 'lib/mr/read_model/query_expression.rb', line 150

def read_model_block
  @read_model_block
end

Instance Method Details

#combine_sql(sql, params = nil) ⇒ Object 



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# File 'lib/mr/read_model/query_expression.rb', line 172

def combine_sql(sql, params = nil)
  "#{sql} #{self.operator_sql} #{self.read_model_class.build_sql(params)}"
end

#read_model_class ⇒ Object 



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# File 'lib/mr/read_model/query_expression.rb', line 158

def read_model_class
  @read_model_class ||= begin
    c = Class.new do
      # TODO - fix circular require
      require 'mr/read_model'
      require 'mr/read_model/set_querying'
      include MR::ReadModel
      include MR::ReadModel::SetQuerying
    end
    c.class_eval(&self.read_model_block)
    c
  end
end