Class: Linkage::MetaObject

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(object, side = nil) ⇒ MetaObject

Creates a new MetaObject.

Parameters:

  • object (Object) —

    This can be a Field, Function or a regular Ruby object (Fixnum, String, etc). If ‘object` is not static (a Field or a Function that contains one or more Field objects), you should specify which “side” of the linkage the object belongs to (left-hand side or right-hand side) in the `side` argument.

  • side (Symbol) (defaults to: nil) —

    ‘:lhs` for left-hand side or `:rhs` for right-hand side



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# File 'lib/linkage/meta_object.rb', line 15

def initialize(object, side = nil)
  @object = object
  @static = object.kind_of?(Linkage::Data) ? object.static? : true
  if !side.nil? && side != :lhs && side != :rhs
    raise ArgumentError, "invalid `side` argument, must be :lhs or :rhs"
  end
  @side = side
end

Instance Attribute Details

#object ⇒ Object (readonly)

Returns the value of attribute object.



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# File 'lib/linkage/meta_object.rb', line 3

def object
  @object
end

#side ⇒ Object 



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# File 'lib/linkage/meta_object.rb', line 24

def side
  if !@static && @side.nil?
    raise RuntimeError, "Object is dynamic and side is not set"
  end
  @side
end

Instance Method Details

#collation ⇒ Symbol

Returns the collation of the underlying object.

Returns:

  • (Symbol) 


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# File 'lib/linkage/meta_object.rb', line 126

def collation
  if @object.kind_of?(Linkage::Data)
    @object.collation
  else
    nil
  end
end

#database_type ⇒ Object 



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# File 'lib/linkage/meta_object.rb', line 43

def database_type
  ds = dataset
  ds ? ds.database_type : nil
end

#dataset ⇒ Object 



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# File 'lib/linkage/meta_object.rb', line 31

def dataset
  @object.kind_of?(Linkage::Data) ? @object.dataset : nil
end

#dataset=(dataset) ⇒ Object 



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# File 'lib/linkage/meta_object.rb', line 35

def dataset=(dataset)
  if @object.kind_of?(Linkage::Data)
    @object.dataset = dataset
  else
    raise RuntimeError, "You can't set the dataset of a non-data object."
  end
end

#datasets_equal?(other) ⇒ Boolean

Returns true if the argument has the same dataset as the instance.

Parameters:

Returns:

  • (Boolean) 


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# File 'lib/linkage/meta_object.rb', line 64

def datasets_equal?(other)
  other.is_a?(Linkage::MetaObject) && other.dataset == self.dataset
end

#merge(other) ⇒ Linkage::MergeField

Returns a Linkage::MergeField if both objects are Data objects, otherwise, raises an exception.

Returns:



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# File 'lib/linkage/meta_object.rb', line 102

def merge(other)
  if @object.kind_of?(Linkage::Data) && other.object.kind_of?(Linkage::Data)
    @object.merge(other.object)
  else
    raise ArgumentError, "Cannot merge a non-data object"
  end
end

#name ⇒ Symbol?

Return the name of the object for Data objects, nil for others.

Returns:

  • (Symbol, nil) 


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# File 'lib/linkage/meta_object.rb', line 90

def name
  if @object.kind_of?(Linkage::Data)
    @object.name
  else
    nil
  end
end

#objects_equal?(other) ⇒ Boolean

Returns true if the argument has the same object as the instance.

Parameters:

Returns:

  • (Boolean) 


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# File 'lib/linkage/meta_object.rb', line 56

def objects_equal?(other)
  other.is_a?(Linkage::MetaObject) && other.object == self.object
end

#raw? ⇒ Boolean

Returns true if underlying object is not a subclass of Data.

Returns:

  • (Boolean) 


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# File 'lib/linkage/meta_object.rb', line 135

def raw?
  !@object.kind_of?(Linkage::Data)
end

#ruby_type ⇒ Hash

Returns the Ruby type of the underlying object.

Returns:

  • (Hash)

See Also:



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# File 'lib/linkage/meta_object.rb', line 115

def ruby_type
  if @object.kind_of?(Linkage::Data)
    @object.ruby_type
  else
    {:type => @object.class}
  end
end

#static? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/linkage/meta_object.rb', line 48

def static?
  @static
end

#to_expr ⇒ Object

Returns an expression suitable for use in Sequel queries.

Returns:

  • (Object) 


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# File 'lib/linkage/meta_object.rb', line 70

def to_expr
  if @object.kind_of?(Linkage::Data)
    @object.to_expr
  else
    @object
  end
end

#to_identifier ⇒ Sequel::SQL::Identifier, Object

Returns a Sequel identifier for Data objects, or the object itself.

Returns:

  • (Sequel::SQL::Identifier, Object) 


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# File 'lib/linkage/meta_object.rb', line 80

def to_identifier
  if @object.kind_of?(Linkage::Data)
    Sequel::SQL::Identifier.new(@object.to_expr)
  else
    @object
  end
end