Passing parameters to transactions

Arbitrary parameters can be passed to transactions by setting the params attribute when declaring the transaction. This feature is handy to re-use the same transaction code for multiple calls but with different parameters.

A basic example:

db._executeTransaction({
  collections: { },
  action: "function (params) { return params[1]; }",
  params: [ 1, 2, 3 ]
});

The above example will return 2.

Some example that uses collections:

db._executeTransaction({
  collections: { 
    write: "users",
    read: [ "c1", "c2" ]
  },
  action: "function (params) { var db = require('internal').db; var doc = db.c1.document(params['c1Key']); db.users.save(doc); doc = db.c2.document(params['c2Key']); db.users.save(doc);}", 
  params: { 
    c1Key: "foo", 
    c2Key: "bar" 
  }
});

Disallowed operations

Some operations are not allowed inside ArangoDB transactions:

• creation and deletion of collections (db._create(), db._drop(), db._rename())
• creation and deletion of indexes (db.ensure…Index(), db.dropIndex())

If an attempt is made to carry out any of these operations during a transaction, ArangoDB will abort the transaction with error code 1653 (disallowed operation inside transaction).