Event filters

Event filters can be used to

  • filter which unsynced / unreplicated differences should be processed by rubyrep
  • implement custom sync / replication actions

This is done by assigning the custom event filter to the (table specific) option :event_filter.
An event filter implements the before_sync and before_replicate methods1.

The before_sync / before_replicate methods

  • are called for each each detected sync / replication difference
  • must return true for rubyrep to proceed with syncing / replicating the difference
  • can use the calling parameters to access both databases for custom actions

1 It is OK to only implement one of the methods.

Sync filter

before_sync is called with

  • table: name of the left table (of the sync difference)
  • key: the column_name => value hash of the primary key of the sync difference
  • sync_helper: a SyncHelper through which the database can be accessed
  • type: type of sync difference (:left, :right or :conflict)
  • row:
    • for :left or :right differences: the column_name => value pairs of the unsynced row
    • for :conflict: an array of conflicting left and right row

Replication filter

before_replicate is called with

  • table: name of the left table (of the unreplicated change)
  • key: the column_name => value hash of the primary key of the changed row
  • replication_helper: a ReplicationHelper enabling database access
  • diff: the ReplicationDifference describing the unreplicated change.

Example

The following simple example configures rubyrep to sync / replicate only accounts with a primary key < 100:


...

class AccountFilter
  def before_sync(table, key, sync_helper, type, row)
    key['id'] < 100
  end

  def before_replicate(table, key, replication_helper, diff)
    key['id'] < 100
  end
end 

config.add_table_option 'accounts', :event_filter => AccountFilter.new

...