Merge pull request #15 from subomi/subomi/feat/refactor-migration-pre…

…dicate

fix: improved migration matching logic

requestmigrations.go

@@ -5,8 +5,9 @@ import (
 	"errors"
 	"io"
 	"net/http"
-	"net/url"
+	"reflect"
 	"sort"
+	"strings"
 	"sync"
 	"time"
 
@@ -27,22 +28,24 @@ var (
 	ErrCurrentVersionCannotBeEmpty = errors.New("Current Version field cannot be empty")
 )
 
-// migrations := Migrations{
-//   "2023-02-28": []Migration{
-//     Migration{},
-//	   Migration{},
-//	 },
-// }
-type Migrations map[string][]Migration
-
 // Migration is the core interface each transformation in every version
 // needs to implement. It includes two predicate functions and two
 // transformation functions.
 type Migration interface {
 	Migrate(data []byte, header http.Header) ([]byte, http.Header, error)
-	ShouldMigrateConstraint(url *url.URL, method string, data []byte, isReq bool) bool
 }
 
+// Migrations is an array of migrations declared by each handler.
+type Migrations []Migration
+
+// migrations := Migrations{
+//   "2023-02-28": []Migration{
+//     Migration{},
+//	   Migration{},
+//	 },
+// }
+type MigrationStore map[string]Migrations
+
 type GetUserVersionFunc func(req *http.Request) (string, error)
 
 // RequestMigrationOptions is used to configure the RequestMigration type.
@@ -74,7 +77,7 @@ type RequestMigration struct {
 	iv       string
 
 	mu         sync.Mutex
-	migrations Migrations
+	migrations MigrationStore
 }
 
 func NewRequestMigration(opts *RequestMigrationOptions) (*RequestMigration, error) {
@@ -98,7 +101,7 @@ func NewRequestMigration(opts *RequestMigrationOptions) (*RequestMigration, erro
 		iv = "v0"
 	}
 
-	migrations := Migrations{
+	migrations := MigrationStore{
 		iv: []Migration{},
 	}
 
@@ -114,7 +117,7 @@ func NewRequestMigration(opts *RequestMigrationOptions) (*RequestMigration, erro
 	}, nil
 }
 
-func (rm *RequestMigration) RegisterMigrations(migrations Migrations) error {
+func (rm *RequestMigration) RegisterMigrations(migrations MigrationStore) error {
 	rm.mu.Lock()
 	defer rm.mu.Unlock()
 
@@ -135,7 +138,7 @@ func (rm *RequestMigration) RegisterMigrations(migrations Migrations) error {
 	return nil
 }
 
-func (rm *RequestMigration) VersionRequest(r *http.Request) error {
+func (rm *RequestMigration) VersionRequest(r *http.Request, handler string) error {
 	from, err := rm.getUserVersion(r)
 	if err != nil {
 		return err
@@ -154,15 +157,15 @@ func (rm *RequestMigration) VersionRequest(r *http.Request) error {
 	startTime := time.Now()
 	defer rm.observeRequestLatency(from, to, startTime)
 
-	err = m.applyRequestMigrations(r)
+	err = m.applyRequestMigrations(r, handler)
 	if err != nil {
 		return err
 	}
 
 	return nil
 }
 
-func (rm *RequestMigration) VersionResponse(r *http.Request, body []byte) ([]byte, error) {
+func (rm *RequestMigration) VersionResponse(r *http.Request, body []byte, handler string) ([]byte, error) {
 	from, err := rm.getUserVersion(r)
 	if err != nil {
 		return nil, err
@@ -178,7 +181,7 @@ func (rm *RequestMigration) VersionResponse(r *http.Request, body []byte) ([]byt
 		return body, nil
 	}
 
-	return m.applyResponseMigrations(r, r.Header, body)
+	return m.applyResponseMigrations(r, r.Header, body, handler)
 }
 
 func (rm *RequestMigration) getUserVersion(req *http.Request) (*Version, error) {
@@ -241,10 +244,10 @@ type migrator struct {
 	to         *Version
 	from       *Version
 	versions   []*Version
-	migrations Migrations
+	migrations MigrationStore
 }
 
-func Newmigrator(from, to *Version, avs []*Version, migrations Migrations) (*migrator, error) {
+func Newmigrator(from, to *Version, avs []*Version, migrations MigrationStore) (*migrator, error) {
 	if !from.IsValid() || !to.IsValid() {
 		return nil, ErrInvalidVersion
 	}
@@ -265,7 +268,7 @@ func Newmigrator(from, to *Version, avs []*Version, migrations Migrations) (*mig
 	}, nil
 }
 
-func (m *migrator) applyRequestMigrations(req *http.Request) error {
+func (m *migrator) applyRequestMigrations(req *http.Request, handler string) error {
 	if m.versions == nil {
 		return nil
 	}
@@ -288,11 +291,8 @@ func (m *migrator) applyRequestMigrations(req *http.Request) error {
 			continue
 		}
 
-		for _, migration := range migrations {
-			if !migration.ShouldMigrateConstraint(req.URL, req.Method, data, true) {
-				continue
-			}
-
+		migration := m.retrieveHandlerRequestMigration(migrations, handler)
+		if migration != nil {
 			data, header, err = migration.Migrate(data, header)
 			if err != nil {
 				return err
@@ -308,7 +308,7 @@ func (m *migrator) applyRequestMigrations(req *http.Request) error {
 	return nil
 }
 
-func (m *migrator) applyResponseMigrations(r *http.Request, header http.Header, data []byte) ([]byte, error) {
+func (m *migrator) applyResponseMigrations(r *http.Request, header http.Header, data []byte, handler string) ([]byte, error) {
 	var err error
 
 	for i := len(m.versions); i > 0; i-- {
@@ -323,17 +323,42 @@ func (m *migrator) applyResponseMigrations(r *http.Request, header http.Header,
 			return data, nil
 		}
 
-		for _, migration := range migrations {
-			if !migration.ShouldMigrateConstraint(r.URL, r.Method, data, false) {
-				continue
-			}
-
+		migration := m.retrieveHandlerResponseMigration(migrations, handler)
+		if migration != nil {
 			data, _, err = migration.Migrate(data, header)
 			if err != nil {
 				return nil, ErrServerError
 			}
 		}
+
 	}
 
 	return data, nil
 }
+
+func (m *migrator) retrieveHandlerResponseMigration(migrations Migrations, handler string) Migration {
+	return m.retrieveHandlerMigration(migrations, strings.Join([]string{handler, "response"}, ""))
+}
+
+func (m *migrator) retrieveHandlerRequestMigration(migrations Migrations, handler string) Migration {
+	return m.retrieveHandlerMigration(migrations, strings.Join([]string{handler, "request"}, ""))
+}
+
+func (m *migrator) retrieveHandlerMigration(migrations Migrations, handler string) Migration {
+	for _, migration := range migrations {
+		var mv reflect.Value
+
+		mv = reflect.ValueOf(migration)
+
+		if mv.Kind() == reflect.Ptr {
+			mv = mv.Elem()
+		}
+
+		fName := strings.ToLower(mv.Type().Name())
+		if strings.HasPrefix(fName, strings.ToLower(handler)) {
+			return migration
+		}
+	}
+
+	return nil
+}

requestmigrations_test.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"net/http"
 	"net/http/httptest"
-	"net/url"
 	"strings"
 	"testing"
 
@@ -36,10 +35,11 @@ func newRequestMigration(t *testing.T) *RequestMigration {
 }
 
 func registerBasicMigrations(t *testing.T, rm *RequestMigration) {
-	migrations := &Migrations{
-		"2023-03-01": []Migration{
-			&combineNamesMigration{},
-			&splitNameMigration{},
+	migrations := &MigrationStore{
+		"2023-03-01": Migrations{
+			&getUserResponseCombineNamesMigration{},
+			&createUserRequestSplitNameMigration{},
+			&createUserResponseCombineNamesMigration{},
 		},
 	}
 
@@ -53,21 +53,10 @@ type oldUser struct {
 	Email    string `json:"email"`
 	FullName string `json:"full_name"`
 }
-type combineNamesMigration struct{}
 
-func (c *combineNamesMigration) ShouldMigrateConstraint(
-	url *url.URL,
-	method string,
-	body []byte,
-	isReq bool) bool {
-
-	isUserPath := url.Path == "/users"
-	isValidType := isReq == false
-
-	return isUserPath && isValidType
-}
+type getUserResponseCombineNamesMigration struct{}
 
-func (c *combineNamesMigration) Migrate(
+func (c *getUserResponseCombineNamesMigration) Migrate(
 	body []byte,
 	h http.Header) ([]byte, http.Header, error) {
 
@@ -89,22 +78,9 @@ func (c *combineNamesMigration) Migrate(
 	return body, h, nil
 }
 
-type splitNameMigration struct{}
-
-func (c *splitNameMigration) ShouldMigrateConstraint(
-	url *url.URL,
-	method string,
-	body []byte,
-	isReq bool) bool {
-
-	isUserPath := url.Path == "/users"
-	isPostMethod := method == http.MethodPost
-	isValidType := isReq == true
-
-	return isUserPath && isPostMethod && isValidType
-}
+type createUserRequestSplitNameMigration struct{}
 
-func (c *splitNameMigration) Migrate(
+func (c *createUserRequestSplitNameMigration) Migrate(
 	body []byte,
 	h http.Header) ([]byte, http.Header, error) {
 
@@ -129,9 +105,33 @@ func (c *splitNameMigration) Migrate(
 	return body, h, nil
 }
 
+type createUserResponseCombineNamesMigration struct{}
+
+func (c *createUserResponseCombineNamesMigration) Migrate(
+	body []byte,
+	h http.Header) ([]byte, http.Header, error) {
+
+	var newuser user
+	err := json.Unmarshal(body, &newuser)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	var user oldUser
+	user.Email = newuser.Email
+	user.FullName = strings.Join([]string{newuser.FirstName, newuser.LastName}, " ")
+
+	body, err = json.Marshal(&user)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return body, h, nil
+}
+
 func createUser(t *testing.T, rm *RequestMigration) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		err := rm.VersionRequest(r)
+		err := rm.VersionRequest(r, "createUser")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -158,7 +158,7 @@ func createUser(t *testing.T, rm *RequestMigration) http.Handler {
 			t.Fatal(err)
 		}
 
-		resBody, err := rm.VersionResponse(r, body)
+		resBody, err := rm.VersionResponse(r, body, "createUser")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -255,7 +255,7 @@ func Test_VersionRequest(t *testing.T) {
 
 func getUser(t *testing.T, rm *RequestMigration) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		err := rm.VersionRequest(r)
+		err := rm.VersionRequest(r, "getUser")
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -271,7 +271,7 @@ func getUser(t *testing.T, rm *RequestMigration) http.Handler {
 			t.Fatal(err)
 		}
 
-		resBody, err := rm.VersionResponse(r, body)
+		resBody, err := rm.VersionResponse(r, body, "getUser")
 		if err != nil {
 			t.Fatal(err)
 		}