Middleware

About

Middleware are Go functions that can be shipped with Docker image, allowing request and response contents to be modified on the fly.

Signature

Same signature for both request and response middleware functions:

func (reqResource *connexions_plugin.RequestedResource) ([]byte, error) {
    // your code here
}

before request middleware:
If middleware returns an error or any non-nil response, the request will be aborted and the response will be returned to the client.

Middleware response function:

func PetstoreAfter(reqResource *connexions_plugin.RequestedResource) ([]byte, error) {
    log.Printf("[PetstoreAfter] req path: %s\n", reqResource.URL.String())
    switch reqResource.Method {
    case http.MethodGet:
        switch reqResource.Resource {
        case "/pets":
            pets := []map[string]any{
                {"name": "dog", "id": 1, "tag": "pet"},
                {"name": "cat", "id": 2, "tag": "pet"},
            }
            log.Println("[PetstoreAfter] returning modified pets")
            return json.Marshal(pets)
        }
    }
    return reqResource.Response.Data, nil
}

connexions_plugin package is a small package that provides typing support for the middleware functions.
User provided functions should be built as go plugins using same go version as connexions.

Middleware location

Functions should be placed in the plugins directory inside the mapped data directory.
Filenames are completely arbitrary and can be named as you wish.
But the names of the middleware functions should be:
- unique - start with UpperCase - specified in the service configuration:

Other conditions:
- Package name should be main. - Go version should exactly match the version used to build the Connexions image.

services:
  petstore:
    middleware:
      beforeHandler:
        - PetstoreBefore
      afterHandler:
        - PetstoreAfter