method

from_json

Ruby on Rails latest stable (v7.1.3.2) - 2 notes - Class: ActiveRecord::Serialization

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What's this?

Method deprecated or moved

This method is deprecated or moved on the latest stable version. The last existing version (v2.3.8) is shown here.

These similar methods exist in v7.1.3.2:

ActiveModel::Serializers::JSON#from_json

from_json(json) public

No documentation

This method has no description. You can help the Ruby on Rails community by adding new notes.

Show source

# File activerecord/lib/active_record/serializers/json_serializer.rb, line 86
    def from_json(json)
      self.attributes = ActiveSupport::JSON.decode(json)
      self
    end

July 24, 2009

1 thank

Instance method

Please note that this is an instance method, not a class method (which seemed more logical for me and took me a while to see what’s wrong). So, you call it like this:

User.new.from_json '{"id": 1, "name": "DHH"}' # RIGHT!

not like this:

User.from_json '{"id": 1, "name": "DHH"}' # WRONG!

May 4, 2010

0 thanks

Be careful about ActiveRecord::Base.include_root_in_json

If you have set ActiveRecord::Base.include_root_in_json = true, then when you do .to_json on an object, the output will begin with the class name rather than just a hash of attributes.

from the rails docs

konata = User.find(1)
ActiveRecord::Base.include_root_in_json = true
konata.to_json
=> { "user": {"id": 1, "name": "Konata Izumi", "age": 16,
          "created_at": "2006/08/01", "awesome": true} }

if you try to pass this output as the argument to from_json, things will blow up.

User.new.from_json(konata.to_json[“user”]) will just pass in the attribute hash and will work.

Also, note that if you’ve use attr_accessible to limit mass assignment, you’ll have problems if you try pass in attributes that are not allowed to be mass assigned.