refactor: define repository and service error (#40)

internal/api/project.go

@@ -30,20 +30,20 @@ func (api projectApi) HandleList(c *gin.Context) {
 		return
 	}
 
-	res, err := api.usecase.ListProjects(request)
+	res, ucErr := api.usecase.ListProjects(request)
 
-	if err != nil && err.Code() == usecase.InvalidArgumentError {
-		resErr := UseCaseErrorToResponse(err)
+	if ucErr != nil && ucErr.Code() == usecase.InvalidArgumentError {
+		resErr := UseCaseErrorToResponse(ucErr)
 		c.JSON(http.StatusBadRequest, model.ProjectListErrorResponse{
-			Message: UseCaseErrorToMessage(err),
+			Message: UseCaseErrorToMessage(ucErr),
 			User:    resErr.User,
 		})
 		return
 	}
 
-	if err != nil {
+	if ucErr != nil {
 		c.JSON(http.StatusInternalServerError, model.ApplicationErrorResponse{
-			Message: UseCaseErrorToMessage(err),
+			Message: UseCaseErrorToMessage(ucErr),
 		})
 		return
 	}
@@ -60,21 +60,21 @@ func (api projectApi) HandleCreate(c *gin.Context) {
 		return
 	}
 
-	res, err := api.usecase.CreateProject(request)
+	res, ucErr := api.usecase.CreateProject(request)
 
-	if err != nil && err.Code() == usecase.InvalidArgumentError {
-		resErr := UseCaseErrorToResponse(err)
+	if ucErr != nil && ucErr.Code() == usecase.InvalidArgumentError {
+		resErr := UseCaseErrorToResponse(ucErr)
 		c.JSON(http.StatusBadRequest, model.ProjectCreateErrorResponse{
-			Message: UseCaseErrorToMessage(err),
+			Message: UseCaseErrorToMessage(ucErr),
 			User:    resErr.User,
 			Project: resErr.Project,
 		})
 		return
 	}
 
-	if err != nil {
+	if ucErr != nil {
 		c.JSON(http.StatusInternalServerError, model.ApplicationErrorResponse{
-			Message: UseCaseErrorToMessage(err),
+			Message: UseCaseErrorToMessage(ucErr),
 		})
 		return
 	}

internal/domain/user_id_object.go

@@ -1,6 +1,8 @@
 package domain
 
-import "fmt"
+import (
+	"fmt"
+)
 
 type UserIdObject struct {
 	value string

internal/repository/error.go

@@ -0,0 +1,33 @@
+package repository
+
+import (
+	"fmt"
+)
+
+type ErrorCode string
+
+const (
+	ReadFailurePanic  ErrorCode = "read failure"
+	WriteFailurePanic ErrorCode = "write failure"
+)
+
+type Error struct {
+	code ErrorCode
+	err  error
+}
+
+func Errorf(code ErrorCode, format string, args ...any) *Error {
+	return &Error{code: code, err: fmt.Errorf(format, args...)}
+}
+
+func (e Error) Error() string {
+	return fmt.Sprintf("%s: %s", e.code, e.err.Error())
+}
+
+func (e Error) Unwrap() error {
+	return e.err
+}
+
+func (e Error) Code() ErrorCode {
+	return e.code
+}

internal/repository/project.go

@@ -1,8 +1,6 @@
 package repository
 
 import (
-	"fmt"
-
 	"cloud.google.com/go/firestore"
 	"github.com/kumachan-mis/knodeledge-api/internal/db"
 	"github.com/kumachan-mis/knodeledge-api/internal/record"
@@ -13,8 +11,8 @@ import (
 const ProjectCollection = "projects"
 
 type ProjectRepository interface {
-	FetchUserProjects(userId string) (map[string]record.ProjectEntry, error)
-	InsertProject(entry record.ProjectWithoutAutofieldEntry) (string, *record.ProjectEntry, error)
+	FetchUserProjects(userId string) (map[string]record.ProjectEntry, *Error)
+	InsertProject(entry record.ProjectWithoutAutofieldEntry) (string, *record.ProjectEntry, *Error)
 }
 
 type projectRepository struct {
@@ -25,7 +23,7 @@ func NewProjectRepository(client firestore.Client) ProjectRepository {
 	return projectRepository{client: client}
 }
 
-func (r projectRepository) FetchUserProjects(userId string) (map[string]record.ProjectEntry, error) {
+func (r projectRepository) FetchUserProjects(userId string) (map[string]record.ProjectEntry, *Error) {
 	iter := r.client.Collection(ProjectCollection).
 		Where("userId", "==", userId).
 		Documents(db.FirestoreContext())
@@ -41,7 +39,7 @@ func (r projectRepository) FetchUserProjects(userId string) (map[string]record.P
 		var entry record.ProjectEntry
 		err = snapshot.DataTo(&entry)
 		if err != nil {
-			return nil, fmt.Errorf("failed to convert snapshot to entry: %w", err)
+			return nil, Errorf(ReadFailurePanic, "failed to convert snapshot to entry: %w", err)
 		}
 
 		projects[snapshot.Ref.ID] = entry
@@ -50,7 +48,7 @@ func (r projectRepository) FetchUserProjects(userId string) (map[string]record.P
 	return projects, nil
 }
 
-func (r projectRepository) InsertProject(entry record.ProjectWithoutAutofieldEntry) (string, *record.ProjectEntry, error) {
+func (r projectRepository) InsertProject(entry record.ProjectWithoutAutofieldEntry) (string, *record.ProjectEntry, *Error) {
 	ref, _, err := r.client.Collection(ProjectCollection).
 		Add(db.FirestoreContext(), map[string]any{
 			"name":        entry.Name,
@@ -60,18 +58,18 @@ func (r projectRepository) InsertProject(entry record.ProjectWithoutAutofieldEnt
 			"updatedAt":   firestore.ServerTimestamp,
 		})
 	if err != nil {
-		return "", nil, fmt.Errorf("failed to insert project: %w", err)
+		return "", nil, Errorf(WriteFailurePanic, "failed to insert project: %w", err)
 	}
 
 	snapshot, err := ref.Get(db.FirestoreContext())
 	if err != nil {
-		return "", nil, fmt.Errorf("failed to get inserted project: %w", err)
+		return "", nil, Errorf(ReadFailurePanic, "failed to get inserted project: %w", err)
 	}
 
 	var entryWithTimestamp record.ProjectEntry
 	err = snapshot.DataTo(&entryWithTimestamp)
 	if err != nil {
-		return "", nil, fmt.Errorf("failed to convert snapshot to entry: %w", err)
+		return "", nil, Errorf(ReadFailurePanic, "failed to convert snapshot to entry: %w", err)
 	}
 
 	return ref.ID, &entryWithTimestamp, nil

internal/repository/project_test.go

@@ -1,6 +1,7 @@
 package repository_test
 
 import (
+	"fmt"
 	"testing"
 	"time"
 
@@ -16,9 +17,9 @@ func TestFetchUserProjectsValidDocument(t *testing.T) {
 	r := repository.NewProjectRepository(*client)
 
 	userId := testutil.ReadOnlyUserId()
-	projects, err := r.FetchUserProjects(userId)
+	projects, rErr := r.FetchUserProjects(userId)
 
-	assert.NoError(t, err)
+	assert.Nil(t, rErr)
 
 	assert.Len(t, projects, 2)
 
@@ -42,25 +43,30 @@ func TestFetchUserProjectsNoDocument(t *testing.T) {
 	r := repository.NewProjectRepository(*client)
 
 	userId := testutil.UnknownUserId()
-	projects, err := r.FetchUserProjects(userId)
+	projects, rErr := r.FetchUserProjects(userId)
 
-	assert.NoError(t, err)
+	assert.Nil(t, rErr)
 
 	assert.Empty(t, projects)
 }
 
 func TestFetchUserProjectsInvalidDocument(t *testing.T) {
 	tt := []struct {
-		name   string
-		userId string
+		name          string
+		userId        string
+		expectedError string
 	}{
 		{
 			name:   "should return error when project name is invalid",
 			userId: testutil.ErrorUserId(0),
+			expectedError: "failed to convert snapshot to entry: record.ProjectEntry.name: " +
+				"firestore: cannot set type string to int",
 		},
 		{
 			name:   "should return error when project description is invalid",
 			userId: testutil.ErrorUserId(1),
+			expectedError: "failed to convert snapshot to entry: record.ProjectEntry.description: " +
+				"firestore: cannot set type string to bool",
 		},
 	}
 
@@ -69,9 +75,11 @@ func TestFetchUserProjectsInvalidDocument(t *testing.T) {
 			client := db.FirestoreClient()
 			r := repository.NewProjectRepository(*client)
 
-			projects, err := r.FetchUserProjects(tc.userId)
+			projects, rErr := r.FetchUserProjects(tc.userId)
 
-			assert.ErrorContains(t, err, "failed to convert snapshot to entry:")
+			assert.NotNil(t, rErr)
+			assert.Equal(t, repository.ReadFailurePanic, rErr.Code())
+			assert.Equal(t, fmt.Sprintf("read failure: %s", tc.expectedError), rErr.Error())
 			assert.Nil(t, projects)
 		})
 	}
@@ -88,10 +96,10 @@ func TestInsertProjectValidEntry(t *testing.T) {
 		UserId:      userId,
 	}
 
-	id, project, err := r.InsertProject(entry)
+	id, project, rErr := r.InsertProject(entry)
 	now := time.Now()
 
-	assert.NoError(t, err)
+	assert.Nil(t, rErr)
 
 	assert.NotEmpty(t, id)
 	assert.Equal(t, entry.Name, project.Name)

internal/service/error.go

@@ -0,0 +1,33 @@
+package service
+
+import (
+	"fmt"
+)
+
+type ErrorCode string
+
+const (
+	DomainFailurePanic     ErrorCode = "domain failure"
+	RepositoryFailurePanic ErrorCode = "repository failure"
+)
+
+type Error struct {
+	code ErrorCode
+	err  error
+}
+
+func Errorf(code ErrorCode, format string, args ...any) *Error {
+	return &Error{code: code, err: fmt.Errorf(format, args...)}
+}
+
+func (e Error) Error() string {
+	return fmt.Sprintf("%s: %s", e.code, e.err.Error())
+}
+
+func (e Error) Unwrap() error {
+	return e.err
+}
+
+func (e Error) Code() ErrorCode {
+	return e.code
+}