doc: improved example to use the most recent version

README.md

@@ -12,41 +12,34 @@
 ```
 
 ## Usage
-This package exposes primarily one API - `Migrate`. It is used to migrate and rollback changes to your request and response respectively. Here's a short exmaple:
+This package exposes primarily one API - `Migrate`. It is used to migrate and rollback changes to your request and response respectively. Here's a short example:
 
 ```go
 package main 
 
 func createUser(r *http.Request, w http.ResponseWriter) {
-  err, res, rollback := rm.Migrate(r, "createUser")
+  // Identify version and transform the request payload.
+  err, vw, rollback := rm.Migrate(r, "createUser")
   if err != nil {
      w.Write("Bad Request")
   }
-  defer rollback(w)
 
-  payload, err := io.ReadAll(r.Body)
-  if err != nil {
-    w.Write("Bad Request")
-  }
+  // Setup response transformation callback.
+  defer rollback(w)
 
-  var userObject user
-  err = json.Unmarshal(payload, &userObject)
+  // ...Perform core business logic...
+  data, err := createUserObject(body)
   if err != nil {
-    w.Write("Bad Request")
-  }
-
-  userObject = user{
-    Email:     userObject.Email,
-    FirstName: userObject.FirstName,
-    LastName:  userObject.LastName,
+    return err 
   }
 
-  body, err := json.Marshal(userObject)
+  // Write response
+  body, err := json.Marshal(data)
   if err != nil {
     w.Write("Bad Request")
   }
 
-  res.SetBody(body)
+  vw.Write(body)
 }
 
 ```

example/advanced/main.go

@@ -0,0 +1,7 @@
+package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("TODO: Write a more complex example")
+}

example/basic/helper/helper.go

@@ -0,0 +1,29 @@
+package helper
+
+import "encoding/json"
+
+type ServerResponse struct {
+	Status  bool            `json:"status"`
+	Message string          `json:"message"`
+	Data    json.RawMessage `json:"data,omitempty"`
+}
+
+func GenerateSuccessResponse(payload interface{}, message string) ([]byte, error) {
+	data, err := json.Marshal(payload)
+	if err != nil {
+		return nil, err
+	}
+
+	s := &ServerResponse{
+		Status:  true,
+		Message: message,
+		Data:    data,
+	}
+
+	res, err := json.Marshal(s)
+	if err != nil {
+		return nil, err
+	}
+
+	return res, nil
+}

example/basic/main.go

@@ -1,7 +1,9 @@
 package main
 
 import (
-	"encoding/json"
+	"basicexample/helper"
+	v20230401 "basicexample/v20230401"
+	v20230501 "basicexample/v20230501"
 	"log"
 	"math/rand"
 	"net/http"
@@ -27,12 +29,12 @@ func main() {
 		log.Fatal(err)
 	}
 
-	rm.RegisterMigrations(rms.Migrations{
+	rm.RegisterMigrations(rms.MigrationStore{
 		"2023-05-01": []rms.Migration{
-			&expandProfileForUserMigration{},
+			&v20230501.ListUserResponseMigration{},
 		},
 		"2023-04-01": []rms.Migration{
-			&combineNamesForUserMigration{},
+			&v20230401.ListUserResponseMigration{},
 		},
 	})
 
@@ -55,8 +57,7 @@ func main() {
 func buildMux(api *API) http.Handler {
 	m := mux.NewRouter()
 
-	m.Handle("/users",
-		api.rm.VersionAPI(http.HandlerFunc(api.ListUser))).Methods("GET")
+	m.HandleFunc("/users", api.ListUser).Methods("GET")
 	m.HandleFunc("/users/{id}", api.GetUser).Methods("GET")
 
 	reg := prometheus.NewRegistry()
@@ -69,11 +70,6 @@ func buildMux(api *API) http.Handler {
 }
 
 // api models
-type ServerResponse struct {
-	Status  bool            `json:"status"`
-	Message string          `json:"message"`
-	Data    json.RawMessage `json:"data,omitempty"`
-}
 
 // define api
 type API struct {
@@ -82,6 +78,14 @@ type API struct {
 }
 
 func (a *API) ListUser(w http.ResponseWriter, r *http.Request) {
+	err, vw, rollback := a.rm.Migrate(r, "ListUser")
+	if err != nil {
+		w.WriteHeader(http.StatusBadRequest)
+		return
+	}
+
+	defer rollback(w)
+
 	// Generate a random Int type number between 1 and 10
 	randNum := rand.Intn(2-1+1) + 1
 	time.Sleep(time.Duration(randNum) * time.Second)
@@ -92,13 +96,13 @@ func (a *API) ListUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	res, err := generateSuccessResponse(users, "users retrieved successfully")
+	res, err := helper.GenerateSuccessResponse(users, "users retrieved successfully")
 	if err != nil {
 		w.WriteHeader(http.StatusBadGateway)
 		return
 	}
 
-	w.Write(res)
+	vw.Write(res)
 }
 
 func (a *API) GetUser(w http.ResponseWriter, r *http.Request) {
@@ -109,32 +113,11 @@ func (a *API) GetUser(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	res, err := generateSuccessResponse(user, "user retrieved successfully")
+	res, err := helper.GenerateSuccessResponse(user, "user retrieved successfully")
 	if err != nil {
 		w.WriteHeader(http.StatusBadGateway)
 		return
 	}
 
 	w.Write(res)
 }
-
-// helpers
-func generateSuccessResponse(payload interface{}, message string) ([]byte, error) {
-	data, err := json.Marshal(payload)
-	if err != nil {
-		return nil, err
-	}
-
-	s := &ServerResponse{
-		Status:  true,
-		Message: message,
-		Data:    data,
-	}
-
-	res, err := json.Marshal(s)
-	if err != nil {
-		return nil, err
-	}
-
-	return res, nil
-}

example/basic/requestmigrations.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"basicexample/helper"
 	"encoding/json"
 	"net/http"
 	"net/url"
@@ -9,9 +10,9 @@ import (
 )
 
 // Migrations
-type combineNamesForUserMigration struct{}
+type ListUserResponseMigration struct{}
 
-func (c *combineNamesForUserMigration) ShouldMigrateConstraint(
+func (c *ListUserResponseMigration) ShouldMigrateConstraint(
 	url *url.URL,
 	method string,
 	data []byte,
@@ -24,7 +25,7 @@ func (c *combineNamesForUserMigration) ShouldMigrateConstraint(
 	return isUserPath && isGetMethod && isValidType
 }
 
-func (c *combineNamesForUserMigration) Migrate(
+func (c *ListUserResponseMigration) Migrate(
 	body []byte,
 	h http.Header) ([]byte, http.Header, error) {
 	type oldUser struct {
@@ -36,7 +37,7 @@ func (c *combineNamesForUserMigration) Migrate(
 		UpdatedAt time.Time `json:"updated_at"`
 	}
 
-	var res ServerResponse
+	var res helper.ServerResponse
 	err := json.Unmarshal(body, &res)
 	if err != nil {
 		return nil, nil, err
@@ -60,7 +61,7 @@ func (c *combineNamesForUserMigration) Migrate(
 		newUsers = append(newUsers, &oldUser)
 	}
 
-	body, err = generateSuccessResponse(&newUsers, "users retrieved successfully")
+	body, err = helper.GenerateSuccessResponse(&newUsers, "users retrieved successfully")
 	if err != nil {
 		return nil, nil, err
 	}
@@ -96,7 +97,7 @@ func (e *expandProfileForUserMigration) ShouldMigrateConstraint(
 func (e *expandProfileForUserMigration) Migrate(
 	body []byte,
 	h http.Header) ([]byte, http.Header, error) {
-	var res ServerResponse
+	var res helper.ServerResponse
 	err := json.Unmarshal(body, &res)
 	if err != nil {
 		return nil, nil, err
@@ -121,7 +122,7 @@ func (e *expandProfileForUserMigration) Migrate(
 		newUsers = append(newUsers, &oldUser)
 	}
 
-	body, err = generateSuccessResponse(&newUsers, "users retrieved successfully")
+	body, err = helper.GenerateSuccessResponse(&newUsers, "users retrieved successfully")
 	if err != nil {
 		return nil, nil, err
 	}

example/basic/v20230401/requestmigrations.go

@@ -0,0 +1,66 @@
+package v20230401
+
+import (
+	"basicexample/helper"
+	"encoding/json"
+	"net/http"
+	"strings"
+	"time"
+)
+
+// Migrations
+type ListUserResponseMigration struct{}
+
+func (c *ListUserResponseMigration) Migrate(
+	body []byte,
+	h http.Header) ([]byte, http.Header, error) {
+	type oldUser struct {
+		UID       string    `json:"uid"`
+		Email     string    `json:"email"`
+		FullName  string    `json:"full_name"`
+		Profile   string    `json:"profile"`
+		CreatedAt time.Time `json:"created_at"`
+		UpdatedAt time.Time `json:"updated_at"`
+	}
+
+	var res helper.ServerResponse
+	err := json.Unmarshal(body, &res)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var users []*oldUser20230501
+	err = json.Unmarshal(res.Data, &users)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var newUsers []*oldUser
+	for _, u := range users {
+		var oldUser oldUser
+		oldUser.UID = u.UID
+		oldUser.Email = u.Email
+		oldUser.FullName = strings.Join([]string{u.FirstName, u.LastName}, " ")
+		oldUser.Profile = u.Profile
+		oldUser.CreatedAt = u.CreatedAt
+		oldUser.UpdatedAt = u.UpdatedAt
+		newUsers = append(newUsers, &oldUser)
+	}
+
+	body, err = helper.GenerateSuccessResponse(&newUsers, "users retrieved successfully")
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return body, h, nil
+}
+
+type oldUser20230501 struct {
+	UID       string    `json:"uid"`
+	Email     string    `json:"email"`
+	FirstName string    `json:"first_name"`
+	LastName  string    `json:"last_name"`
+	Profile   string    `json:"profile"`
+	CreatedAt time.Time `json:"created_at"`
+	UpdatedAt time.Time `json:"updated_at"`
+}