Class: LegacyMigrations::Squirrel::Query

Inherits:
Object
  • Object
show all
Defined in:
lib/legacy_migrations/squirrel/squirrel.rb

Overview

The Query is what contains the query and is what handles execution and pagination of the result set.

Defined Under Namespace

Classes: Condition, ConditionGroup

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(model, from_record = nil, &blk) ⇒ Query

Creates a Query specific to the given model (which is a class that descends from AR::Base) and a block that will be run to find the conditions for the #find call.



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 62

def initialize model, from_record = nil, &blk
  @model = model
  @joins = nil
  @from = from_record
  @binding = blk && blk.binding
  @conditions = ConditionGroup.new(@model, "AND", @binding, @from, &blk)
  @conditions.assign_joins( join_dependency )
end

Instance Attribute Details

#conditions ⇒ Object (readonly)

Returns the value of attribute conditions.



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 58

def conditions
  @conditions
end

#model ⇒ Object (readonly)

Returns the value of attribute model.



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 58

def model
  @model
end

Instance Method Details

#execute(*args) ⇒ Object

Runs the block which builds the conditions. If requested, paginates the result_set. If the first parameter to #find is :query (instead of :all or :first), then the query object itself is returned. Useful for debugging, but not much else.



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 85

def execute *args
  if args.first == :query
    self
  else
    opts = args.last.is_a?(Hash) ? args.last : {}
    results = []

    pagination = opts.delete(:paginate) || {}
    model.send(:with_scope, :find => opts) do
      @conditions.paginate(pagination) unless pagination.empty?
      results = model.find args[0], to_find_parameters
      if @conditions.paginate?
        paginate_result_set results, to_find_parameters
      end
    end
    results
  end
end

#from ⇒ Object 



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 104

def from
  @from
end

#join_dependency ⇒ Object

Builds the dependencies needed to find what AR plans to call the tables in the query by finding and sending what would be passed in as the include parameter to #find. This is a necessary step because what AR calls tables deeply nested might not be completely obvious.)



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 75

def join_dependency
  jd = ::ActiveRecord::Associations::ClassMethods::JoinDependency
  @join_dependency ||= jd.new model,
                              @conditions.to_find_include,
                              nil
end

#paginate_result_set(set, conditions) ⇒ Object

Used by #execute to paginates the result set if pagination was requested. In this case, it adds pages and total_results accessors to the result set. See Paginator for more details.



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 146

def paginate_result_set set, conditions
  limit = conditions.delete(:limit)
  offset = conditions.delete(:offset)
   
  class << set
    attr_reader :pages
    attr_reader :total_results
  end
   
  total_results = model.count(conditions)
  set.instance_variable_set("@pages",
                            Paginator.new( :count => total_results,
                                           :limit => limit,
                                           :offset => offset) )
  set.instance_variable_set("@total_results", total_results)
  set.extend( Squirrel::WillPagination )
end

#to_find_conditions ⇒ Object

Delegates the to_find_conditions call to the root ConditionGroup



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 119

def to_find_conditions
  @conditions.to_find_conditions
end

#to_find_include ⇒ Object

Delegates the to_find_include call to the root ConditionGroup



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 124

def to_find_include
  @conditions.to_find_include
end

#to_find_limit ⇒ Object

Delegates the to_find_limit call to the root ConditionGroup



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 134

def to_find_limit
  @conditions.to_find_limit
end

#to_find_offset ⇒ Object

Delegates the to_find_offset call to the root ConditionGroup



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 139

def to_find_offset
  @conditions.to_find_offset
end

#to_find_order ⇒ Object

Delegates the to_find_order call to the root ConditionGroup



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 129

def to_find_order
  @conditions.to_find_order
end

#to_find_parameters ⇒ Object 



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# File 'lib/legacy_migrations/squirrel/squirrel.rb', line 108

def to_find_parameters
  find_parameters = {}
  find_parameters[:conditions] = to_find_conditions unless to_find_conditions.blank?
  find_parameters[:include ] = to_find_include unless to_find_include.blank?
  find_parameters[:order ] = to_find_order unless to_find_order.blank?
  find_parameters[:limit ] = to_find_limit unless to_find_limit.blank?
  find_parameters[:offset ] = to_find_offset unless to_find_offset.blank?
  find_parameters
end