Partial generation #

The features described in this article are useful not only for the code generation, but also for other go-asyncapi outputs, such as generation of client application, infra files, etc.

Pub/Sub-only #

The easiest way to control the code generation is to use the --only-pub and --only-sub command-line options (or appropriate configuration options) to generate only the publishing or subscribing code, respectively. In this case, the entities (e.g. operations), that support the direction opposite to the selected one, will be skipped.

Example:

go-asyncapi code --only-pub my_asyncapi.yaml

or in the configuration file:

code:
  onlyPublish: true

However, such way might be too broad for your needs. Let’s consider the more precise ways.

x-ignore field #

To exclude a particular entity from the code generation, you can use the x-ignore special field in the AsyncAPI document. All references to this entity in the generated Go code are automatically replaced with generic types such as any.

The following example shows how to exclude a channel:

channels:
  myChannel:
    x-ignore: true
    messages:
      myMessage:
        payload:
          type: string

Code layout #

Code layout can be used to control the code generation process in a most flexible way.

So, to select the entities, you need to set the rule conditions they should match to. Entities, that didn’t match any rule, will be discarded. If an entity matches several rules, it will be handled by all matching rules separately.

In a rule condition we can check entities name, kind, document location, protocol, etc. The rules can be combined to select entities by multiple conditions. See configuration reference for more details.

Let’s consider an example of the code layout configuration:

layout:
  - nameRe: "^acme_corp_"
    artifactKinds: ["server", "channel", "operation"]
    reusePackagePath: "github.com/myorg/myproject/pkg/acme_corp"
  - nameRe: "^acme_corp_"
    artifactKinds: ["server", "channel", "operation", "message"]
    not: true
    render:
      file: "{{.Kind}}s/{{.Object | goIDUpper }}.go"

In this example, the code for the entities whose names start with acme_corp_ will be reused from the github.com/myorg/myproject/pkg/acme_corp package, except for the messages, which will be skipped, because they don’t match any rule condition. Other entities will be handled by the second rule.