Module: IdentityCache::WithPrimaryIndex::ClassMethods

Defined in:
lib/identity_cache/with_primary_index.rb

Instance Method Summary collapse

Instance Method Details

#cache_index(*fields, unique: false) ⇒ Object

Declares a new index in the cache for the class where IdentityCache was included.

IdentityCache will add a fetch_by_field1_and_field2_and_…field for every index.

Example:

class Product
  include IdentityCache
  cache_index :name, :vendor
end

Will add Product.fetch_by_name_and_vendor

Parameters

fields Array of symbols or strings representing the fields in the index

Options

  • unique: if the index would only have unique values. Default is false



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# File 'lib/identity_cache/with_primary_index.rb', line 55

def cache_index(*fields, unique: false)
  attribute_proc = -> { primary_key }
  cache_attribute_by_alias(attribute_proc, alias_name: :id, by: fields, unique: unique)

  field_list = fields.join("_and_")
  arg_list = (0...fields.size).collect { |i| "arg#{i}" }.join(',')

  if unique
    instance_eval(<<-CODE, __FILE__, __LINE__ + 1)
      def fetch_by_#{field_list}(#{arg_list}, includes: nil)
        id = fetch_id_by_#{field_list}(#{arg_list})
        id && fetch_by_id(id, includes: includes)
      end

      # exception throwing variant
      def fetch_by_#{field_list}!(#{arg_list}, includes: nil)
        fetch_by_#{field_list}(#{arg_list}, includes: includes) or raise IdentityCache::RecordNotFound
      end
    CODE
  else
    instance_eval(<<-CODE, __FILE__, __LINE__ + 1)
      def fetch_by_#{field_list}(#{arg_list}, includes: nil)
        ids = fetch_id_by_#{field_list}(#{arg_list})
        ids.empty? ? ids : fetch_multi(ids, includes: includes)
      end
    CODE
  end

  if fields.length == 1
    instance_eval(<<-CODE, __FILE__, __LINE__ + 1)
      def fetch_multi_by_#{field_list}(index_values, includes: nil)
        ids = fetch_multi_id_by_#{field_list}(index_values).values.flatten(1)
        return ids if ids.empty?
        fetch_multi(ids, includes: includes)
      end
    CODE
  end
end

#cached_primary_index ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/identity_cache/with_primary_index.rb', line 25

def cached_primary_index
  @cached_primary_index ||= Cached::PrimaryIndex.new(self)
end

#exists_with_identity_cache?(id) ⇒ Boolean

Similar to ActiveRecord::Base#exists? will return true if the id can be found in the cache or in the DB.

Returns:

  • (Boolean) 


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# File 'lib/identity_cache/with_primary_index.rb', line 96

def exists_with_identity_cache?(id)
  !!fetch_by_id(id)
end

#expire_primary_key_cache_index(id) ⇒ Object

Invalidates the primary cache index for the associated record. Will not invalidate cached attributes.



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# File 'lib/identity_cache/with_primary_index.rb', line 131

def expire_primary_key_cache_index(id)
  cached_primary_index.expire(id)
end

#fetch(id, includes: nil) ⇒ Object

Default fetcher added to the model on inclusion, it behaves like ActiveRecord::Base.find, but will raise IdentityCache::RecordNotFound if the id is not in the cache.



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# File 'lib/identity_cache/with_primary_index.rb', line 113

def fetch(id, includes: nil)
  fetch_by_id(id, includes: includes) || raise(
    IdentityCache::RecordNotFound, "Couldn't find #{name} with ID=#{id}"
  )
end

#fetch_by_id(id, includes: nil) ⇒ Object

Default fetcher added to the model on inclusion, it behaves like ActiveRecord::Base.where(id: id).first



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# File 'lib/identity_cache/with_primary_index.rb', line 102

def fetch_by_id(id, includes: nil)
  ensure_base_model
  raise_if_scoped
  record = cached_primary_index.fetch(id)
  prefetch_associations(includes, [record]) if record && includes
  record
end

#fetch_multi(*ids, includes: nil) ⇒ Object

Default fetcher added to the model on inclusion, if behaves like ActiveRecord::Base.find_all_by_id



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# File 'lib/identity_cache/with_primary_index.rb', line 121

def fetch_multi(*ids, includes: nil)
  ensure_base_model
  raise_if_scoped
  ids.flatten!(1)
  records = cached_primary_index.fetch_multi(ids)
  prefetch_associations(includes, records) if includes
  records
end

#primary_cache_index_enabled ⇒ Object 



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# File 'lib/identity_cache/with_primary_index.rb', line 29

def primary_cache_index_enabled
  true
end