How to set attributes with different names than a DB schema - ruby-on-rails

Question

I am a newbie Ruby developer. I cannot figure out how to create an ActiveRecord model with different attributes names than defined in a DB schema
Consider the following schema
create_table "sync_tasks", force: :cascade do |t|
t.string "name"
t.string "path"
t.string "task_type"
t.string "status"
t.boolean "async", default: false
t.boolean "direct_download", default: true
t.datetime "created_at", null: false
t.datetime "completed_at"
t.datetime "updated_at", null: false
end
And I have the following payload
{
"name" : "Sync /var/www/",
"path" : "/var/www",
"directDownload": true,
"async" : false,
"taskType" : "directory"
}
And trying to create my model like that
class SyncTask < ApplicationRecord
TYPE_DB='db'
TYPE_FILE='file'
TYPE_DIRECTORY='directory'
def initialize(params)
# super
#task_type = params[:taskType]
#direct_download = params[:directDownload]
#path = params[:path]
#status = params[:status]
#async = params[:async]
end
end
When I try to save it throws an error
<NoMethodError: undefined method `[]' for nil:NilClass>
Also I am not able to access field like that
new_task = SyncTask.new(allowed_task_params)
new_task.task_type
It throws the following error
#<NoMethodError: undefined method `task_type' for #<SyncTask not initialized>>
In case I uncomment the super call it gives another error
#<ActiveModel::UnknownAttributeError: unknown attribute 'taskType' for SyncTask.>
What I am doing wrong ? How can I use different attributes names and initialize the model by myself ?
Thanks

Answer 1

You can transform the keys , for example:
=> payload = { "name": "Sync /var/www/", "path": "/var/www", "directDownload": true, "taskType": "directory" }
=> h = payload.transform_keys { |key| key.to_s.underscore } # only since v4.0.2
=> h = Hash[payload.map { |(k, v)| [k.to_s.underscore, v] }] # before v.4.0.2
#> {"name"=>"Sync /var/www/", "path"=>"/var/www", "direct_download"=>true, "task_type"=>"directory"}
=> new_task = SyncTask.new(h)
You shouldn't use the initialize method on AR models. If you still need to use initialize, use after_initialize hook. Because with the initialize we have to declare the super, so it is best to use the callback.