method

fetch_multi

v6.1.3.1 - Show latest stable - 0 notes - Class: ActiveSupport::Cache::Store

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What's this?

fetch_multi(*names) public

Fetches data from the cache, using the given keys. If there is data in the cache with the given keys, then that data is returned. Otherwise, the supplied block is called for each key for which there was no data, and the result will be written to the cache and returned. Therefore, you need to pass a block that returns the data to be written to the cache. If you do not want to write the cache when the cache is not found, use #read_multi.

Returns a hash with the data for each of the names. For example:

cache.write("bim", "bam")
cache.fetch_multi("bim", "unknown_key") do |key|
  "Fallback value for key: #{key}"
end
# => { "bim" => "bam",
#      "unknown_key" => "Fallback value for key: unknown_key" }

Options are passed to the underlying cache implementation. For example:

cache.fetch_multi("fizz", expires_in: 5.seconds) do |key|
  "buzz"
end
# => {"fizz"=>"buzz"}
cache.read("fizz")
# => "buzz"
sleep(6)
cache.read("fizz")
# => nil

Show source

# File activesupport/lib/active_support/cache.rb, line 440
      def fetch_multi(*names)
        raise ArgumentError, "Missing block: `Cache#fetch_multi` requires a block." unless block_given?

        options = names.extract_options!
        options = merged_options(options)

        instrument :read_multi, names, options do |payload|
          reads   = read_multi_entries(names, **options)
          writes  = {}
          ordered = names.index_with do |name|
            reads.fetch(name) { writes[name] = yield(name) }
          end

          payload[:hits] = reads.keys
          payload[:super_operation] = :fetch_multi

          write_multi(writes, options)

          ordered
        end
      end

fetch_multi

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