Rails-成功调用ActiveRecord.save后，id仍为0

Question

I have an entity which is an ActiveRecord. When I call entity.save it returns true , and the entity.new_record? returns false , but the entity.id is 0. In the entities table, the new row was still inserted with the correct incremented id. It's very weird.

My rails version was 3.2.8, database is Mysql, and use gem mysql2 (0.3.11). I've struggled with this for a whole day...

Code added: json is a string from frontend.

        o = JSON.parse(CGI.unescape(json))
        if o.has_key?('cls') then
            @r = o['cls']
            cls = o['cls']
            #create
            if o['action'] == 0 then
                entity = Object.const_get(cls).new
                o.each_pair do |k,v|
                    # entity.respond_to?  check method exist
                    if defined? entity[k] then
                        entity[k] = v
                    end
                end

                r = entity.save!

and the model (generated by rails g model):

class Node < ActiveRecord::Base
  attr_accessible :iNodeId, :level, :name, :pNodeId, :stationId, :type
end                    

Answer 1

Works by changing

if defined? entity[k] then 

to this

if defined? entity[k] and k != 'id' then