Module: Liszt::ClassMethods

Defined in:
lib/liszt.rb

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.extended(base) ⇒ Object 



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# File 'lib/liszt.rb', line 58

def self.extended(base)
  class << base
    attr_reader :liszt_sort_by, :liszt_append_new_items
  end
end

Instance Method Details

#initialize_list!(obj = {}, &block) ⇒ Object 



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# File 'lib/liszt.rb', line 64

def initialize_list!(obj={}, &block)
  objects = liszt_relation(obj).to_a

  # If the caller provided a block, or if they passed in a default
  # with the :sort_by option, sort the objects by that block's
  # output before populating the list with their ids. If not, put
  # the objects in descending order by id.
  ids = case
    when block_given?
      objects.sort_by(&block).map(&:id)
    when @liszt_sort_by
      objects.sort_by(&@liszt_sort_by).map(&:id)
    else
      objects.map(&:id).sort.reverse
    end

  ordered_list(obj).clear_and_populate!(ids)
  ids
end

#liszt_key(obj = {}) ⇒ Object (private)

Return the key for the Redis list that includes the given object.



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# File 'lib/liszt.rb', line 161

def liszt_key(obj={})
  key = "liszt:#{table_name}"
  @liszt_scope.each do |scope|
    key << ":#{scope}:#{obj[scope]}"
  end
  key
end

#liszt_relation(obj = {}) ⇒ Object (private)

Return a relation/scope containing objects eligible to be in the list that includes the given object.



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# File 'lib/liszt.rb', line 171

def liszt_relation(obj={})
  if @liszt_query.nil?
    query = ['1 = 1']

    @liszt_conditions.each do |key, value|
      query.first << " AND (#{table_name}.#{key} "
      if value.nil?
        query.first << "IS NULL)"
      else
        query.first << "= ?)"
        query << value
      end
    end

    @liszt_scope.each do |scope|
      query.first << " AND (#{table_name}.#{scope} = ?)"
    end

    @liszt_query = query
  end

  where(@liszt_query + @liszt_scope.map { |scope| obj[scope] })
end

#meets_list_conditions?(obj = {}) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/liszt.rb', line 143

def meets_list_conditions?(obj={})
  @liszt_conditions.all? { |key, value| obj[key] == value }
end

#ordered_list(obj = {}) ⇒ Object 



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# File 'lib/liszt.rb', line 84

def ordered_list(obj={})
  Liszt::RedisList.new(liszt_key(obj))
end

#ordered_list_ids(obj = {}) ⇒ Object 



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# File 'lib/liszt.rb', line 92

def ordered_list_ids(obj={})
  if ordered_list_initialized?(obj)
    ordered_list(obj).all
  else
    initialize_list!(obj)
  end
end

#ordered_list_initialized?(obj = {}) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/liszt.rb', line 88

def ordered_list_initialized?(obj={})
  ordered_list(obj).initialized?
end

#ordered_list_items(obj = {}, opts = {}) ⇒ Object 



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# File 'lib/liszt.rb', line 100

def ordered_list_items(obj={}, opts={})
  force_refresh = opts.delete(:force_refresh) || false
  previously_initialized = ordered_list_initialized?(obj)

  # If the list isn't initialized already, we can trust ordered_list_ids to
  # do the initialization correctly and ignore the force_refresh flag.
  if force_refresh && previously_initialized
    refresh_ordered_list(obj)
  else
    list_ids = ordered_list_ids(obj)
    records  = liszt_relation(obj).to_a
    real_ids = records.map(&:id)

    if real_ids.to_set == list_ids.to_set
      records.sort_by { |obj| list_ids.index(obj.id) }
    else
      refresh_ordered_records obj, list_ids, records, real_ids
    end
  end
end

#refresh_ordered_list(obj = {}) ⇒ Object

Synchronizes the ordered list with the database, returning the relevant records in order.



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# File 'lib/liszt.rb', line 123

def refresh_ordered_list(obj={})
  list_ids   = ordered_list_ids(obj)
  records    = liszt_relation(obj).to_a
  real_ids   = records.map(&:id)

  refresh_ordered_records obj, list_ids, records, real_ids
end

#refresh_ordered_records(obj, list_ids, records, real_ids) ⇒ Object (private) 



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# File 'lib/liszt.rb', line 149

def refresh_ordered_records(obj, list_ids, records, real_ids)
  merged_ids = Liszt.merge_id_lists(
                 real_ids, list_ids, @liszt_append_new_items)

  if merged_ids != list_ids
    ordered_list(obj).clear_and_populate!(merged_ids)
  end

  records.sort_by { |obj| merged_ids.index(obj.id) }
end

#update_ordered_list(obj, new_ids) ⇒ Object

Update the given object's list with the given ids. Returns the final list of ids, which may be different from the given list if the given list was inconsistent with the database.



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# File 'lib/liszt.rb', line 134

def update_ordered_list(obj, new_ids)
  records    = ordered_list_items(obj, force_refresh: true)
  real_ids   = records.map(&:id)
  merged_ids = Liszt.merge_id_lists(
                 real_ids, new_ids, @liszt_append_new_items)

  ordered_list(obj).clear_and_populate!(merged_ids)
end