Class: LiveRecord::PublicationsChannel

Inherits:
BaseChannel
  • Object
show all
Defined in:
app/channels/live_record/publications_channel.rb

Overview

This channel streams new records to connected clients whenever the “where” condition supplied by the client matches This implementation can be quite inefficient because there’s only one pub-sub queue used for each model, but because of constraints ( see github.com/jrpolidario/live_record/issues/2 ) and because Users are authorised-validated anyway in each stream, then there’s already an overhead delay. I am prioritising development convenience (as Rails does), in order to achieve a simpler API; in this example, it would be something like in JS: ‘LiveRecord.Model.all.Book.subscribe(is_enabled: true)`

Defined Under Namespace

Modules: SearchAdapters

Instance Method Summary collapse

Instance Method Details

#subscribed ⇒ Object 



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# File 'app/channels/live_record/publications_channel.rb', line 9

def subscribed
  model_class = params[:model_name].safe_constantize

  if !(model_class && model_class < ApplicationRecord)
    respond_with_error(:bad_request, 'Not a correct model name')
    reject_subscription
  end

  stream_from "live_record:publications:#{params[:model_name].underscore}", coder: ActiveSupport::JSON do |message|
    newly_created_record = model_class.find(message['attributes']['id'])

    @authorised_attributes ||= authorised_attributes(newly_created_record, current_user)
    
    active_record_relation = SearchAdapters.mapped_active_record_relation(
      model_class: model_class,
      conditions_hash: params[:where].to_h,
      current_user: current_user,
      authorised_attributes: @authorised_attributes
    )

    if active_record_relation.exists?(id: newly_created_record.id)
      # if not just :id
      if @authorised_attributes.size > 1
        message = { 'action' => 'create', 'attributes' => message['attributes'] }
        response = filtered_message(message, @authorised_attributes)
        transmit response if response.present?
      end
    end
  end
end

#sync_records(data) ⇒ Object 



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# File 'app/channels/live_record/publications_channel.rb', line 40

def sync_records(data)
  params = data.symbolize_keys
  model_class = params[:model_name].safe_constantize

  if model_class && model_class < ApplicationRecord

    records = model_class.where(
      'created_at >= ?', DateTime.parse(params[:stale_since]) - LiveRecord.configuration.sync_record_buffer_time
    )

    # we `transmmit` a message back to client for each matching record
    records.find_each do |record|
      # now we check each record if it is part of the "where" condition
      current_authorised_attributes = authorised_attributes(record, current_user)

      active_record_relation = SearchAdapters.mapped_active_record_relation(
        model_class: model_class,
        conditions_hash: params[:where].to_h,
        current_user: current_user,
        authorised_attributes: current_authorised_attributes
      )

      if active_record_relation.exists?(id: record)
        message = { 'action' => 'create', 'attributes' => record.attributes }
        response = filtered_message(message, current_authorised_attributes)
        transmit response if response.present?
      end
    end
  else
    respond_with_error(:bad_request, 'Not a correct model name')
    reject_subscription
  end
end