Working with 2.x services

ArangoDB 3 continues to support Foxx services written for ArangoDB 2.8 by running them in a special legacy compatibility mode that provides access to some of the modules and APIs no longer provided in 3.0 and beyond.

Legacy compatibility mode is strictly intended as a temporary stop gap solution for supporting existing services while upgrading to ArangoDB 3.x and is not a permanent feature of ArangoDB or Foxx. It is considered as deprecated from v3.4.0 on.

In order to mark an existing service as a legacy service, make sure the following attribute is defined in the service manifest:

"engines": {
  "arangodb": "^2.8.0"
}

This semantic version range denotes that the service is known to work with ArangoDB 2.8.0 and supports all newer versions of ArangoDB up to but not including 3.0.0 and later.

Any similar version range the does not include 3.0.0 or greater will have the same effect (e.g. ^2.5.0 will also trigger the legacy compatibility mode, as will 1.2.3, but >=2.8.0 will not as it indicates compatibility with all versions greater or equal 2.8.0, not just those within the 2.x version range).

Features supported in legacy compatibility mode

Legacy compatibility mode supports the old manifest format, specifically:

main is ignored
controllers will be mounted as in 2.8
exports will be executed as in 2.8

Additionally the isSystem attribute will be ignored if present but does not result in a warning in legacy compatibility mode.

The Foxx console is available as the console pseudo-global variable (shadowing the global console object).

The service context is available as the applicationContext pseudo-global variable in the controllers, exports, scripts and tests as in 2.8. The following additional properties are available on the service context in legacy compatibility mode:

path() is an alias for 3.x fileName() (using path.join to build file paths)
fileName() behaves as in 2.x (using fs.safeJoin to build file paths)
foxxFileName() is an alias for 2.x fileName
version exposes the service manifest’s version attribute
name exposes the service manifest’s name attribute
options exposes the service’s raw options

The following methods are removed on the service context in legacy compatibility mode:

use() – use @arangodb/foxx/controller instead
apiDocumentation() – use controller.apiDocumentation() instead
registerType() – not supported in legacy compatibility mode

The following modules that have been removed or replaced in 3.0.0 are available in legacy compatibility mode:

@arangodb/foxx/authentication
@arangodb/foxx/console
@arangodb/foxx/controller
@arangodb/foxx/model
@arangodb/foxx/query
@arangodb/foxx/repository
@arangodb/foxx/schema
@arangodb/foxx/sessions
@arangodb/foxx/template_middleware

The @arangodb/foxx module also provides the same exports as in 2.8, namely:

Controller from @arangodb/foxx/controller
createQuery from @arangodb/foxx/query
Model from @arangodb/foxx/model
Repository from @arangodb/foxx/repository
toJSONSchema from @arangodb/foxx/schema
getExports and requireApp from @arangodb/foxx/manager
queues from @arangodb/foxx/queues

Any feature not supported in 2.8 will also not work in legacy compatibility mode. When migrating from an older version of ArangoDB it is a good idea to migrate to ArangoDB 2.8 first for an easier upgrade path.

Additionally, please note the differences laid out in the chapter on migrating from pre-2.8 in the migration guide.

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