Create objects based on received data from params in Ruby on Rails - ruby-on-rails

Question

Description
I am trying to create messages based on selected (via check box) users from the browser in Ruby on Rails.
Snapshot:
Steps to reproduce
My schema
ActiveRecord::Schema.define(version: 2021_11_13_142255) do
create_table "messages", force: :cascade do |t|
t.text "content"
t.integer "user_id"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
end
create_table "users", force: :cascade do |t|
t.string "name"
t.string "role"
t.integer "phone"
t.boolean "admin"
t.datetime "created_at", precision: 6, null: false
t.datetime "updated_at", precision: 6, null: false
end
end
messages_controller.rb
class MessagesController < ApplicationController
def new
#users = User.all
#message = Message.new(message_params)
end
def create
params[:user_objs].each do |u|
# "params.inspect" returns
# {"authenticity_token"=>"[FILTERED]",
# "user_objs"=>
# ["{\"id\":1,\"name\":\"Alex\",\"role\":\"Engineer\",\"phone\":998943333303,\"admin\":true,\"created_at\":\"2021-11-13T14:37:54.962Z\",\"updated_at\":\"2021-11-13T14:37:54.962Z\"}",
# "{\"id\":2,\"name\":\"Lucy\",\"role\":\"Accountant\",\"phone\":998943333303,\"admin\":false,\"created_at\":\"2021-11-13T14:39:52.742Z\",\"updated_at\":\"2021-11-13T14:39:52.742Z\"}"],
# "message"=>{"content"=>"Message from the browser"},
# "commit"=>"Send"}
person = JSON.parse(u)
#message = person.messages.new(message_params)
if #message.save
redirect_to root_path
else
#users = User.all
render :new
end
end
end
private
def message_params
params.permit(
:content,
:user_id
)
end
end
messages => new.html.erb
<div>
<h1>Create and send a new message!</h1>
<%= form_for(#message) do |form| %>
<% if #message.errors.any? %>
<div class="alert alert-danger">
<h5 class="fw-bold">Invalid input!</h5>
<%= #message.errors.full_messages.each do |error| %>
<div><%= error %></div>
<% end %>
</div>
<% end %>
<% #users.each do |u| %>
<div>
<p><%= check_box_tag "user_objs[]", u.to_json %> <%= u.name %></p>
</div>
<% end %>
<p class="mb-3">
<%= form.label :content, class: "form-label" %>
<%= form.text_field :content, class: "form-control", autofocus: true, placeholder: "John_D" %>
</p>
<p class="mb-3">
<%= form.submit "Send", class: "btn btn-primary" %>
</p>
<% end %>
</div>
<%= params.inspect %>
Models
# user.rb
class User < ApplicationRecord
has_many :messages
end
# message.rb
class Message < ApplicationRecord
belongs_to :user
end
Expected behavior
I was expecting the creation of messages for all selected users
Actual behavior
NoMethodError in MessagesController#create
undefined method `messages' for #<Hash:0x000000011fe2b420>
I tried different ways, but can't convert Ruby objects to JSON in my params user_objs[] so that I can parse it in my controller to create messages based on those selected users in the user_objs[] params.
Environment info
ruby -v
ruby 2.7.3p183 (2021-04-05 revision 6847ee089d) [arm64-darwin20]
rails -v
Rails 6.1.4.1
Thanks for any given help 🙏

Answer 1

If you want to create a system where you send a single message to multiple users you would setup a join table:
class User < ApplicationRecord
has_many :user_messages
has_many :recieved_messages, though: :user_messages,
source: :message,
inverse_of: :recipients
end
# rails g model user_message user:belongs_to message:belongs_to read:boolean
class UserMessage < ApplicationRecord
belongs_to :user
belongs_to :message
# make sure to add a compound unique index to the migration as well
validates_uniqueness_of :user_id, scope: :message_id
delegate :content, to: :message
end
class Message < ApplicationRecord
has_many :user_messages
has_many :recipients, though: :user_messages,
source: :user,
inverse_of: :recieved_messages
end
has_many :recipients will create a recipient_ids= setter and a recipient_ids getter that you can use in your form:
<div>
<h1>Create and send a new message!</h1>
<%= form_with(model: #message) do |form| %>
<% if #message.errors.any? %>
<div class="alert alert-danger">
<h5 class="fw-bold">Invalid input!</h5>
<%= #message.errors.full_messages.each do |error| %>
<div><%= error %></div>
<% end %>
</div>
<% end %>
<p class="mb-3">
<%= form.collection_checkboxes(:recipient_ids, #users, :id, :name) %>
</p>
<p class="mb-3">
<%= form.label :content, class: "form-label" %>
<%= form.text_field :content, class: "form-control", autofocus: true, placeholder: "John_D" %>
</p>
<p class="mb-3">
<%= form.submit "Send", class: "btn btn-primary" %>
</p>
<% end %>
</div>
There is absolutely no need to pass the entire record as JSON - you just pass an array of IDs and rails will do all the work of creating the join table rows for you:
class MessagesController < ApplicationController
def new
#users = User.all
#message = Message.new
end
def create
#message = Message.new(message_params)
if #message.save
redirect_to root_path
else
#users = User.all
render :new
end
end
private
def message_params
params.require(:message)
.permit(
:content,
recipient_ids: []
)
end
end
This avoids the complexity of creating multiple records from a single request and the whole conundrum that you're binding the form to a single instance of Message but creating a bunch of records which is bound to lead to confusion.
If you want to create multiple records at once it can be done but the complexity is far higher and you have to deal with stuff like how to handle errors if creating one message fails and this might be beyond your current skill level.

Answer 2

The issue is that you are assigning a json object/hash in person = JSON.parse(u). This is not an active record so when doing person.messages it throws the error. I believe what you need in the create action is something like:
user = JSON.parse(u)
# make sure user.inspect gives you the user object you want
person = User.find(user["id"])
# person.inspect should give you the active record for the user