transaction example

doc.md

Transactions API

To perform transactions use the dirac.tx api. Dirac defaults to using client pooling per request. So a single client must be used over the lifespan of a transaction. The tx will fetch one for you and release it upon .commit().

A dirac tx object has access to the same DALs in addition to transactional commands.

dirac.tx.create()

Creates a new tx object

tx.begin( [callback] )

Issues BEGIN

tx.rollback( [callback] )

Issues ROLLBACK

tx.commit( [ callback ] )

Issues COMMIT and releases the client. Subsequent calls on tx will throw an error.

tx-example.js

it ('should perform transaction', function( done ){
  // Grab a tx client which is used to issue subsequent queries
  var tx = dirac.tx.create();

  // The tx has access to the DALs but uses the tx client instead of
  // the typical client pool
  tx.begin(function(err) {
    if (err) return tx.rollback();
    tx.users.insert({ name: 'red fish' }, function(err) {
      if (err) return tx.rollback();
      tx.users.insert({ name: 'blue fish' }, function(err) {
        if (err) return tx.rollback();

        // End transaction and release client
        tx.commit( done );
      });
    });
  });
});

it ( 'should perform transaction async', function( done ) {
  // This proposed transaction api aims to abstract client management,
  // not control flow. This leave a simple api that the user can use
  // with their choice of control flow library or just straight up
  // callback style.
  var tx = dirac.tx.create();
  var async = utils.async;

  async.series([
    tx.begin.bind(tx)
  , tx.users.insert.bind(tx, { name: 'red fish' })
  , tx.users.insert.bind(tx, { name: 'blue fish' })
  ], function(err, results) {
    assert(!err);
    if ( err ) return tx.rollback();
    tx.commit(done);
  });
});