Add custom converter sample

Author: cschleiden

samples/converter/README.md

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+Shows how a custom `Converter` can be used for inputs/result serialization. This example uses `gob` binary encoding instead of the default JSON one.

samples/converter/converter.go

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+package main
+
+import (
+	"bytes"
+	"context"
+	"encoding/gob"
+	"log"
+	"os"
+	"os/signal"
+	"time"
+
+	"github.com/cschleiden/go-workflows/backend"
+	"github.com/cschleiden/go-workflows/client"
+	"github.com/cschleiden/go-workflows/internal/converter"
+	"github.com/cschleiden/go-workflows/internal/payload"
+	"github.com/cschleiden/go-workflows/samples"
+	"github.com/cschleiden/go-workflows/worker"
+
+	"github.com/google/uuid"
+)
+
+type CustomConverter struct {
+}
+
+var _ converter.Converter = (*CustomConverter)(nil)
+
+func (*CustomConverter) From(data payload.Payload, v interface{}) error {
+	return gob.NewDecoder(bytes.NewReader(data)).Decode(v)
+}
+
+func (*CustomConverter) To(v interface{}) (payload.Payload, error) {
+	var buf bytes.Buffer
+
+	if err := gob.NewEncoder(&buf).Encode(v); err != nil {
+		return nil, err
+	}
+
+	return buf.Bytes(), nil
+}
+
+func main() {
+	ctx, cancel := context.WithCancel(context.Background())
+
+	b := samples.GetBackend("converter", backend.WithConverter(&CustomConverter{}))
+
+	// Run worker
+	w := RunWorker(ctx, b)
+
+	// Start workflow via client
+	c := client.New(b)
+
+	runWorkflow(ctx, c)
+
+	cancel()
+
+	if err := w.WaitForCompletion(); err != nil {
+		panic("could not stop worker" + err.Error())
+	}
+
+	// wait for sigint signal
+	sigint := make(chan os.Signal, 1)
+	signal.Notify(sigint, os.Interrupt)
+	<-sigint
+}
+
+func runWorkflow(ctx context.Context, c client.Client) {
+	wf, err := c.CreateWorkflowInstance(ctx, client.WorkflowInstanceOptions{
+		InstanceID: uuid.NewString(),
+	}, Workflow1, "Hello world"+uuid.NewString(), 42, Inputs{
+		Msg:   "",
+		Times: 0,
+	})
+	if err != nil {
+		log.Fatal(err)
+		panic("could not start workflow")
+	}
+
+	result, err := client.GetWorkflowResult[int](ctx, c, wf, time.Second*10)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("Workflow finished. Result:", result)
+}
+
+func RunWorker(ctx context.Context, mb backend.Backend) worker.Worker {
+	w := worker.New(mb, nil)
+
+	w.RegisterWorkflow(Workflow1)
+
+	w.RegisterActivity(Activity1)
+	w.RegisterActivity(Activity2)
+
+	if err := w.Start(ctx); err != nil {
+		panic("could not start worker")
+	}
+
+	return w
+}

samples/converter/converter_test.go

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+package main
+
+import (
+	"testing"
+
+	"github.com/cschleiden/go-workflows/tester"
+	"github.com/google/uuid"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_Workflow(t *testing.T) {
+	tester := tester.NewWorkflowTester[int](Workflow1)
+
+	tester.OnActivity(Activity1, mock.Anything, 35, 12).Return(47, nil)
+	tester.OnActivity(Activity2, mock.Anything, mock.Anything, mock.Anything).Return(12, nil)
+
+	tester.Execute("Hello world"+uuid.NewString(), 42, Inputs{
+		Msg:   "",
+		Times: 0,
+	})
+
+	require.True(t, tester.WorkflowFinished())
+
+	wr, werr := tester.WorkflowResult()
+	require.Equal(t, 59, wr)
+	require.Empty(t, werr)
+	tester.AssertExpectations(t)
+}

samples/converter/workflow.go

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+package main
+
+import (
+	"context"
+
+	"github.com/cschleiden/go-workflows/activity"
+	"github.com/cschleiden/go-workflows/workflow"
+)
+
+type Inputs struct {
+	Msg   string
+	Times int
+}
+
+func Workflow1(ctx workflow.Context, msg string, times int, inputs Inputs) (int, error) {
+	logger := workflow.Logger(ctx)
+	logger.Debug("Entering Workflow1", "msg", msg, "times", times, "inputs", inputs)
+	defer logger.Debug("Leaving Workflow1")
+
+	r1, err := workflow.ExecuteActivity[int](ctx, workflow.DefaultActivityOptions, Activity1, 35, 12).Get(ctx)
+	if err != nil {
+		panic("error getting activity 1 result")
+	}
+	logger.Debug("R1 result", "r1", r1)
+
+	r2, err := workflow.ExecuteActivity[int](ctx, workflow.DefaultActivityOptions, Activity2).Get(ctx)
+	if err != nil {
+		panic("error getting activity 1 result")
+	}
+	logger.Debug("R2 result", "r2", r2)
+
+	return r1 + r2, nil
+}
+
+func Activity1(ctx context.Context, a, b int) (int, error) {
+	logger := activity.Logger(ctx)
+	logger.Debug("Entering Activity1")
+	defer logger.Debug("Leaving Activity1")
+
+	// time.Sleep(5 * time.Second)
+
+	return a + b, nil
+}
+
+func Activity2(ctx context.Context) (int, error) {
+	logger := activity.Logger(ctx)
+	logger.Debug("Entering Activity2")
+	defer logger.Debug("Leaving Activity2")
+
+	// time.Sleep(1 * time.Second)
+
+	return 12, nil
+}