CODEWITHSUNDEEP
mysqlruby-on-railsruby
pangpang
pangpang

Reputation: 8831

ruby/hash:ActiveSupport::HashWithIndifferentAccess

I store a hash to the mysql,but the result make me confuse:

hash:

{:unique_id=>35, :description=>nil, :title=>{"all"=>"test", "en"=>"test"}...}

and I use the serialize in my model.

serialize :title

The result in mysql like this:

--- !ruby/hash:ActiveSupport::HashWithIndifferentAccess
all: test
en: test

Anyone can tell me what is the meaning? Why there is a ruby/hash:ActiveSupport::HashWithIndifferentAccess in mysql?

Upvotes: 2

Views: 2579

Answers (2)

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121020

TL;DR:

serialize :title, Hash

What’s happening here is that serialize internally will yaml-dump the class instance. And the hashes in rails are monkeypatched to may having an indifferent access. The latter means, that you are free to use both strings and respective symbols as it’s keys:

h = { 'a' => 42 }.with_indifferent_access
puts h[:a]
#⇒ 42

Upvotes: 3

Francesco Belladonna
Francesco Belladonna

Reputation: 11729

Hash needs to be serialized, default serializer is YAML which supports in some way, in the Ruby implementation, the storing of type. Your hash is of type ActiveSupport::HashWithIndifferentAccess, so when fetched back, ruby knows what object should get back (unserializes it to an HashWithIndifferentAccess).

Notice that HashWithIndifferentAccess is a hash where you can access values by using either strings or symbols, so:

tmp = { foo: 'bar' }.with_indifferent_access
tmp[:foo] # => 'bar'
tmp['foo'] # => 'bar'

With a normal hash (Hash.new), you would get instead:

tmp = { foo: 'bar' }
tmp[:foo] # => 'bar'
tmp['foo'] # => nil

Obviously, in mysql, the hash is stored as a simple string, (YAML is plain text with a convention)

Upvotes: 1

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