CodeBench: kompaktoitu Go handlers.go golden — error handling yhdelle riville

kipina-codebench/golden-examples/todo-go.md

@@ -71,7 +71,7 @@ type UpdateTodo struct {
 
 ## handlers.go
 
-CRUD handlers as closures taking *sql.DB. INSERT/UPDATE use RETURNING, sql.ErrNoRows for 404.
+CRUD handlers as closures taking *sql.DB. Key patterns: INSERT RETURNING, sql.ErrNoRows for 404, RowsAffected for delete.
 
 ```go
 package main
@@ -81,67 +81,51 @@ import (
 	"encoding/json"
 	"net/http"
 	"strconv"
-
 	"github.com/go-chi/chi/v5"
 )
 
+// POST — decode JSON, defaults with nil-check, INSERT RETURNING, StatusCreated.
 func createTodo(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		var input CreateTodo
 		if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
+			http.Error(w, err.Error(), http.StatusBadRequest); return
-			return
 		}
 		priority := int64(1)
-		if input.Priority != nil {
+		if input.Priority != nil { priority = *input.Priority }
-			priority = *input.Priority
-		}
 		status := "pending"
-		if input.Status != nil {
+		if input.Status != nil { status = *input.Status }
-			status = *input.Status
-		}
 		var todo Todo
 		err := db.QueryRow(
 			`INSERT INTO todos (title, description, due_date, priority, status)
-			 VALUES (?, ?, ?, ?, ?)
+			 VALUES (?, ?, ?, ?, ?) RETURNING id, title, description, due_date, priority, status`,
-			 RETURNING id, title, description, due_date, priority, status`,
 			input.Title, input.Description, input.DueDate, priority, status,
 		).Scan(&todo.ID, &todo.Title, &todo.Description, &todo.DueDate, &todo.Priority, &todo.Status)
-		if err != nil {
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		w.Header().Set("Content-Type", "application/json")
 		w.WriteHeader(http.StatusCreated)
 		json.NewEncoder(w).Encode(todo)
 	}
 }
 
+// GET list — db.Query + rows.Scan loop, empty slice not nil.
 func listTodos(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		rows, err := db.Query("SELECT id, title, description, due_date, priority, status FROM todos")
-		if err != nil {
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		defer rows.Close()
-		var todos []Todo
+		todos := []Todo{}
 		for rows.Next() {
 			var t Todo
-			if err := rows.Scan(&t.ID, &t.Title, &t.Description, &t.DueDate, &t.Priority, &t.Status); err != nil {
+			rows.Scan(&t.ID, &t.Title, &t.Description, &t.DueDate, &t.Priority, &t.Status)
-				http.Error(w, err.Error(), http.StatusInternalServerError)
-				return
-			}
 			todos = append(todos, t)
 		}
-		if todos == nil {
-			todos = []Todo{}
-		}
 		w.Header().Set("Content-Type", "application/json")
 		json.NewEncoder(w).Encode(todos)
 	}
 }
 
+// GET by id — QueryRow + sql.ErrNoRows → 404.
 func getTodo(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
@@ -149,83 +133,51 @@ func getTodo(db *sql.DB) http.HandlerFunc {
 		err := db.QueryRow(
 			"SELECT id, title, description, due_date, priority, status FROM todos WHERE id = ?", id,
 		).Scan(&todo.ID, &todo.Title, &todo.Description, &todo.DueDate, &todo.Priority, &todo.Status)
-		if err == sql.ErrNoRows {
+		if err == sql.ErrNoRows { http.Error(w, "not found", http.StatusNotFound); return }
-			http.Error(w, "not found", http.StatusNotFound)
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			return
-		}
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		w.Header().Set("Content-Type", "application/json")
 		json.NewEncoder(w).Encode(todo)
 	}
 }
 
+// PUT — fetch existing, merge with input nil-checks, UPDATE RETURNING.
 func updateTodo(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
 		var existing Todo
-		err := db.QueryRow(
+		err := db.QueryRow("SELECT id, title, description, due_date, priority, status FROM todos WHERE id = ?", id,
-			"SELECT id, title, description, due_date, priority, status FROM todos WHERE id = ?", id,
 		).Scan(&existing.ID, &existing.Title, &existing.Description, &existing.DueDate, &existing.Priority, &existing.Status)
-		if err == sql.ErrNoRows {
+		if err == sql.ErrNoRows { http.Error(w, "not found", http.StatusNotFound); return }
-			http.Error(w, "not found", http.StatusNotFound)
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			return
-		}
-		if err != nil {
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		var input UpdateTodo
 		if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
-			http.Error(w, err.Error(), http.StatusBadRequest)
+			http.Error(w, err.Error(), http.StatusBadRequest); return
-			return
-		}
-		if input.Title != nil {
-			existing.Title = *input.Title
-		}
-		if input.Description != nil {
-			existing.Description = input.Description
-		}
-		if input.DueDate != nil {
-			existing.DueDate = input.DueDate
-		}
-		if input.Priority != nil {
-			existing.Priority = *input.Priority
-		}
-		if input.Status != nil {
-			existing.Status = *input.Status
 		}
+		if input.Title != nil { existing.Title = *input.Title }
+		if input.Description != nil { existing.Description = input.Description }
+		if input.DueDate != nil { existing.DueDate = input.DueDate }
+		if input.Priority != nil { existing.Priority = *input.Priority }
+		if input.Status != nil { existing.Status = *input.Status }
 		var updated Todo
 		err = db.QueryRow(
-			`UPDATE todos SET title = ?, description = ?, due_date = ?, priority = ?, status = ?
+			`UPDATE todos SET title=?, description=?, due_date=?, priority=?, status=? WHERE id=?
-			 WHERE id = ?
 			 RETURNING id, title, description, due_date, priority, status`,
 			existing.Title, existing.Description, existing.DueDate, existing.Priority, existing.Status, id,
 		).Scan(&updated.ID, &updated.Title, &updated.Description, &updated.DueDate, &updated.Priority, &updated.Status)
-		if err != nil {
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		w.Header().Set("Content-Type", "application/json")
 		json.NewEncoder(w).Encode(updated)
 	}
 }
 
+// DELETE — Exec + RowsAffected == 0 → 404, else 204.
 func deleteTodo(db *sql.DB) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		id, _ := strconv.ParseInt(chi.URLParam(r, "id"), 10, 64)
 		result, err := db.Exec("DELETE FROM todos WHERE id = ?", id)
-		if err != nil {
+		if err != nil { http.Error(w, err.Error(), http.StatusInternalServerError); return }
-			http.Error(w, err.Error(), http.StatusInternalServerError)
-			return
-		}
 		rows, _ := result.RowsAffected()
-		if rows == 0 {
+		if rows == 0 { http.Error(w, "not found", http.StatusNotFound); return }
-			http.Error(w, "not found", http.StatusNotFound)
-			return
-		}
 		w.WriteHeader(http.StatusNoContent)
 	}
 }