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How to handle a Signal in Go

Use the GetSignalChannel() API from the package to get the Signal Channel. Get a new Selector and pass it the Signal Channel and a callback function to handle the payload.

func YourWorkflowDefinition(ctx workflow.Context, param YourWorkflowParam) error {
// ...
var signal MySignal
signalChan := workflow.GetSignalChannel(ctx, "your-signal-name")
selector := workflow.NewSelector(ctx)
selector.AddReceive(signalChan, func(channel workflow.ReceiveChannel, more bool) {
channel.Receive(ctx, &signal)
// ...
if len(signal.Message) > 0 && signal.Message != "SOME_VALUE" {
return errors.New("signal")
// ...

In the example above, the Workflow code uses workflow.GetSignalChannel to open a workflow.Channel for the Signal type (identified by the Signal name). We then use a workflow.Selector and the AddReceive() to wait on a Signal from this channel. The more bool in the callback function indicates that channel is not closed and more deliveries are possible.

Before completing the Workflow or using Continue-As-New, make sure to do an asynchronous drain on the Signal channel. Otherwise, the Signals will be lost.