Class: OrderQuery::Space

Inherits:
Object
  • Object
show all
Defined in:
lib/order_query/space.rb

Overview

Order specification and a scope

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(base_scope, order_spec) ⇒ Space

Returns a new instance of Space.

Parameters:

  • base_scope (ActiveRecord::Relation)
  • order_spec (Array<Array<Symbol,String>>)

See Also:



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# File 'lib/order_query/space.rb', line 15

def initialize(base_scope, order_spec)
  @base_scope = base_scope
  @columns = order_spec.map do |cond_spec|
    Column.new(base_scope, *cond_spec)
  end
  # add primary key if columns are not unique
  unless @columns.last.unique?
    if @columns.detect(&:unique?)
      fail ArgumentError, 'Unique column must be last'
    end

    @columns << Column.new(base_scope, base_scope.primary_key)
  end
  @order_by_sql = SQL::OrderBy.new(@columns)
end

Instance Attribute Details

#columns ⇒ Array<OrderQuery::Column> (readonly)

Returns:



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# File 'lib/order_query/space.rb', line 9

def columns
  @columns
end

Instance Method Details

#at(record) ⇒ Point

Returns:



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# File 'lib/order_query/space.rb', line 32

def at(record)
  Point.new(record, self)
end

#first ⇒ ActiveRecord::Base

Returns:

  • (ActiveRecord::Base) 


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# File 'lib/order_query/space.rb', line 48

def first
  scope.first
end

#inspect ⇒ Object 



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# File 'lib/order_query/space.rb', line 57

def inspect
  "#<OrderQuery::Space @columns=#{@columns.inspect} "\
  "@base_scope=#{@base_scope.inspect}>"
end

#last ⇒ ActiveRecord::Base

Returns:

  • (ActiveRecord::Base) 


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# File 'lib/order_query/space.rb', line 53

def last
  scope_reverse.first
end

#scope ⇒ ActiveRecord::Relation

Returns scope ordered by columns.

Returns:

  • (ActiveRecord::Relation) —

    scope ordered by columns



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# File 'lib/order_query/space.rb', line 37

def scope
  @scope ||= @base_scope.order(Arel.sql(@order_by_sql.build))
end

#scope_reverse ⇒ ActiveRecord::Relation

Returns scope ordered by columns in reverse.

Returns:

  • (ActiveRecord::Relation) —

    scope ordered by columns in reverse



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# File 'lib/order_query/space.rb', line 42

def scope_reverse
  @scope_reverse ||= @base_scope
                     .order(Arel.sql(@order_by_sql.build_reverse))
end