Go - Websocket.On()

import (
  "fmt"

  "github.com/nitrictech/go-sdk/faas"
  "github.com/nitrictech/go-sdk/nitric"
)

func main() {
  ws, err := nitric.NewWebsocket("public")
  if err != nil {
    return
  }

  ws.On(faas.WebsocketConnect, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
    // handle connections
    return next(ctx)
  })

  ws.On(faas.WebsocketDisconnect, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
    // handle disconnections
    return next(ctx)
  })

  ws.On(faas.WebsocketMessage, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
    // handle messages
    return next(ctx)
  })

  nitric.Run()
}

Parameters

Name
eventType
Required
Required
Type
WebsocketEventType
Description
The type of websocket event to listen for. Can be WebsocketConnect, WebsocketDisconnect, or WebsocketMessage.
Name
middleware
Required
Required
Type
WebsocketMiddleware
Description
The middleware function to use as the handler for Websocket events. If you want to compose more than one middleware use faas.ComposeWebsocketMiddleware.

Examples

Register a handler for message events

ws.On(faas.WebsocketMessage, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
  message := string(ctx.Request.Data())

  fmt.Printf("New Message from %s: %s\n", ctx.Request.ConnectionID(), message)

  return next(ctx)
})

Manage Websocket connections

To store Websocket connections you can use a Nitric collection.

import (
  "fmt"

  "github.com/nitrictech/go-sdk/faas"
  "github.com/nitrictech/go-sdk/nitric"
)

func main() {
  ws, err := nitric.NewWebsocket("public")
  if err != nil {
    return
  }

  connections, err := nitric.NewCollection("connections").With(nitric.CollectionEverything...)
  if err != nil {
    return
  }

  ws.On(faas.WebsocketConnect, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
    err := connections.Doc(ctx.Request.ConnectionID()).Set(ctx.Request.Context(), map[string]interface{}{
      // store any metadata related to the connection here
      "connectionId": ctx.Request.ConnectionID(),
    })
    if err != nil {
      return ctx, err
    }

    return next(ctx)
  })

  ws.On(faas.WebsocketDisconnect, func(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
    // remove the connection from the collection
    err := connections.Doc(ctx.Request.ConnectionID()).Delete(ctx.Request.Context())
    if err != nil {
      return ctx, err
    }

    return next(ctx)
  })

  nitric.Run()
}

Chain functions as a single method handler

import (
  "fmt"

  "github.com/nitrictech/go-sdk/faas"
  "github.com/nitrictech/go-sdk/nitric"
)

func validateMessage(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
  // validate that the message does not contain explicit content

  return next(ctx)
}

func handleMessage(ctx *faas.WebsocketContext, next faas.WebsocketHandler) (*faas.WebsocketContext, error) {
  message := string(ctx.Request.Data())

  fmt.Printf("New Message from %s: %s\n", ctx.Request.ConnectionID(), message)

  return next(ctx)
}

func main() {
  ws, err := nitric.NewWebsocket("public")
  if err != nil {
    return
  }

  ws.On(faas.WebsocketMessage, faas.ComposeWebsocketMiddleware(validateMessage, handleMessage))

  nitric.Run()
}