Class: NoSE::Delete

Inherits:
Statement show all
Includes:
StatementConditions, StatementSupportQuery
Defined in:
lib/nose/statements/delete.rb

Overview

A representation of a delete in the workload

Instance Attribute Summary

Attributes included from StatementConditions

#conditions

Attributes inherited from Statement

#comment, #entity, #eq_fields, #graph, #group, #key_path, #label, #range_field, #text

Class Method Summary collapse

Instance Method Summary collapse

Methods included from StatementConditions

included, #populate_conditions

Methods inherited from Statement

#materialize_view, #read_only?, #requires_insert?, #to_color

Constructor Details

#initialize(params, text, group: nil, label: nil) ⇒ Delete

Returns a new instance of Delete.



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# File 'lib/nose/statements/delete.rb', line 9

def initialize(params, text, group: nil, label: nil)
  super params, text, group: group, label: label

  populate_conditions params
end

Class Method Details

.parse(tree, params, text, group: nil, label: nil) ⇒ Delete

Build a new delete from a provided parse tree

Returns:



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# File 'lib/nose/statements/delete.rb', line 17

def self.parse(tree, params, text, group: nil, label: nil)
  conditions_from_tree tree, params

  Delete.new params, text, group: group, label: label
end

Instance Method Details

#==(other) ⇒ Object Also known as: eql? 



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# File 'lib/nose/statements/delete.rb', line 33

def ==(other)
  other.is_a?(Delete) &&
    @graph == other.graph &&
    entity == other.entity &&
    @conditions == other.conditions
end

#given_fields ⇒ Object

The condition fields are provided with the deletion



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# File 'lib/nose/statements/delete.rb', line 79

def given_fields
  @conditions.each_value.map(&:field)
end

#hash ⇒ Object 



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# File 'lib/nose/statements/delete.rb', line 41

def hash
  @hash ||= [@graph, entity, @conditions].hash
end

#modifies_index?(index) ⇒ Boolean

Index contains the entity to be deleted

Returns:

  • (Boolean) 


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# File 'lib/nose/statements/delete.rb', line 46

def modifies_index?(index)
  index.graph.entities.include? entity
end

#requires_delete?(_index) ⇒ Boolean

Specifies that deletes require deletion

Returns:

  • (Boolean) 


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# File 'lib/nose/statements/delete.rb', line 51

def requires_delete?(_index)
  true
end

#support_queries(index) ⇒ Object

Get the support queries for deleting from an index



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# File 'lib/nose/statements/delete.rb', line 56

def support_queries(index)
  return [] unless modifies_index? index
  select = (index.hash_fields + index.order_fields.to_set) -
           @conditions.each_value.map(&:field).to_set
  return [] if select.empty?

  support_queries = []

  # Build a support query which gets the IDs of the entities being deleted
  graph = @graph.dup
  support_fields = select.select do |field|
    field.parent == entity
  end.to_set
  support_fields << entity.id_field \
    unless @conditions.each_value.map(&:field).include? entity.id_field
  conditions = Hash[@conditions.map { |k, v| [k.dup, v.dup] }]

  support_queries << build_support_query(entity, index, graph,
                                         support_fields, conditions)
  support_queries.compact + support_queries_for_entity(index, select)
end

#unparse ⇒ String

Produce the SQL text corresponding to this delete

Returns:

  • (String) 


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# File 'lib/nose/statements/delete.rb', line 25

def unparse
  delete = "DELETE #{entity.name} "
  delete += "FROM #{from_path @key_path}"
  delete << where_clause

  delete
end