Class: LiveRecord::ChangesChannel

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

Overview

This channel streams changes (update/destroy) from records to connected clients, through ActiveRecord callbacks This also supports syncing (old changes) when a client somehow got disconnected (i.e. network problems), through a separate cache ‘live_record_updates` table.

Instance Method Summary collapse

Instance Method Details

#subscribed ⇒ Object 



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# File 'app/channels/live_record/changes_channel.rb', line 6

def subscribed
  find_record_from_params(params) do |record|
    whitelisted_attributes = LiveRecord::BaseChannel::Helpers.whitelisted_attributes(record, current_user)

    if whitelisted_attributes.present?
      stream_for record, coder: ActiveSupport::JSON do |message|
        begin
          record.reload
        rescue ActiveRecord::RecordNotFound
        end

        whitelisted_attributes = LiveRecord::BaseChannel::Helpers.whitelisted_attributes(record, current_user)

        if whitelisted_attributes.size > 0
          response = filtered_message(message, whitelisted_attributes)
          transmit response if response.present?
        else
          respond_with_error(:forbidden)
          reject_subscription
        end
      end
    else
      respond_with_error(:forbidden)
      reject
    end
  end
end

#sync_record(data) ⇒ Object 



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# File 'app/channels/live_record/changes_channel.rb', line 34

def sync_record(data)
  params = data.symbolize_keys

  find_record_from_params(params) do |record|
    whitelisted_attributes = LiveRecord::BaseChannel::Helpers.whitelisted_attributes(record, current_user)

    if whitelisted_attributes.size > 0
      live_record_updates = nil

      if params[:stale_since].present?
        live_record_updates = LiveRecordUpdate.where(
          recordable_type: record.class.name,
          recordable_id: record.id
        ).where(
          'created_at >= ?', DateTime.parse(params[:stale_since]) - LiveRecord.configuration.sync_record_buffer_time
        )
      end

      # if stale_since is unknown, or there is a live_record_update that has happened while disconnected,
      # then we update the record in the client-side
      if params[:stale_since].blank? || live_record_updates.exists?
        message = { 'action' => 'update', 'attributes' => record.attributes }
        response = filtered_message(message, whitelisted_attributes)
        transmit response if response.present?
      end
    else
      respond_with_error(:forbidden)
      reject_subscription
    end
  end
end