The model plugin is a Goa plugin that validates a Model diagram DSL against a Goa design. The plugin generates errors if there are services present in the Goa design with no corresponding container in the Model diagram. The plugin can also validate that all the containers in the Model diagram have a corresponding service in the Goa design.

To enable the plugin simply import the model plugin dsl package in the Goa design:

import (
  . "goa.design/goa/v3/dsl"
  . "goa.design/plugins/v3/model/dsl"
)

Running goa gen will now execute the plugin and validate that all services have a corresponding container in the model (unless configured otherwise, see below).

The plugin extends the Goa DSL as follows:

• The Model function sets the model Go package and the name of the software system to validate against, this is the only required DSL.
• The ModelContainerNameFormat function sets the format used by the plugin to map service to container names.
• The ModelExcludedTags function sets a list of case-insensitive tags that exclude containers equipped with them from the validation process.
• The ModelComplete function enables the validation that all the containers in the Model diagram have a corresponding service in the Goa design.

All these functions must appear inside the API function:

var _ = API("calc", func() {
  // Set the model package and the name of the software system
  Model("goa.design/model/examples/basic/model", "calc")

  // Set the container name format, default is "%s Service"
  ModelContainerFormat("%s Service")

  // Exclude containers with the "database", "external" and "thirdparty" tags (default)
  ModelExcludedTags("database", "external", "thirdparty")

  // Enable the validation that all the containers in the Model diagram have a
  // corresponding service. Not enabled by default.
  ModelComplete()
})

The plugin also defines the following DSL functions that must appear under a Service definition:

• The ModelContainer function sets the name of the corresponding diagram container. This overrides the name computed from the ContainerNameFormat format.
• The ModelNone function disables the validation for the service.

var _ = Service("add", func() {
  // Set the container name
  ModelContainer("Add Service")
  // ...
})

var _ = Service("no diagram", func() {
  // Disable the validation for this service
  ModelNone()
  // ...
})