Add internal server error to responses

todo.go

@@ -37,9 +37,9 @@ type ListCreateResponse struct {
     Id int
 }
 
-func CheckFatal(err error) {
+func CheckFatal(err error, w http.ResponseWriter) {
     if err != nil {
-        log.Fatal(err)
+        w.WriteHeader(http.StatusInternalServerError)
     }
 }
 
@@ -48,9 +48,6 @@ type Database struct {
 }
 
 
-// getURLParameter takes out the first URL parameter from the path
-// path should be formated as /type/param.
-// It returns a parameter representing a string.
 func getURLParameter(path string) *string {
     param := strings.Split(path, "/")
     if len(param) == 3 {
@@ -60,30 +57,26 @@ func getURLParameter(path string) *string {
     }
 }
 
-// getLists retrieves all the lists from the database.
-// It returns a slice of List structs.
-func getLists(db *sql.DB) []List {
+func getLists(db *sql.DB, w http.ResponseWriter) []List {
     rows, err := db.Query("select * from list")
-    CheckFatal(err)
+    CheckFatal(err, w)
 
     // Retrieve all lists from the query
     res := make([]List, 0)
     for rows.Next() {
         list := List{}
         err := rows.Scan(&list.Id, &list.Name)
-        CheckFatal(err)
+        CheckFatal(err, w)
         res = append(res, list)
     }
 
     return res
 }
 
-// getTasks retrieves all the tasks from the database.
-// It returns a slice of Task structs.
-func getTasks(db *sql.DB, listId int) []Task {
+func getTasks(db *sql.DB, listId int, w http.ResponseWriter) []Task {
     // Query the database for all tasks that references the specified list
     rows, err := db.Query("select * from task where list=$1", listId)
-    CheckFatal(err)
+    CheckFatal(err, w)
 
     // Retrieve all tasks from the query
     res := make([]Task, 0)
@@ -92,36 +85,27 @@ func getTasks(db *sql.DB, listId int) []Task {
         var id, list int
         var done bool
         err := rows.Scan(&id, &name, &done, &list)
-        CheckFatal(err)
+        CheckFatal(err, w)
         res = append(res, Task{Id: id, Name: name, Done: done, ListId: list})
     }
 
     return res
 }
 
-// insertList adds a list to the database with listName as its name.
-// It returns the Id of the list.
-func insertList(db *sql.DB, listName string) int {
+func insertList(db *sql.DB, listName string, w http.ResponseWriter) int {
     var listId int
     err := db.QueryRow("insert into list (name) values ($1) returning id", listName).Scan(&listId)
-    CheckFatal(err)
+    CheckFatal(err, w)
 
     return listId
 }
 
-// insertTask adds a task to the database. 
-// taskName specifies the name of the task, and listId the list that it belongs to.
-func insertTask(db *sql.DB, taskName string, listId int) {
+func insertTask(db *sql.DB, taskName string, listId int, w http.ResponseWriter) {
     _, err := db.Exec("insert into task (name, list) values ($1, $2)", taskName, listId)
     // Handle non-existing list id
-    CheckFatal(err)
+    CheckFatal(err, w)
 }
 
-// listHandler manages requests with regards to the lists.
-// A GET request to /list will retrieve all the lists.
-// A GET request to /list/<id> will retrieve all the tasks of the list with id <id>.
-// A POST request to /list will create a new list with the name provided in the Post Body
-// in the format {"name": "listName"}
 func (db *Database) listHandler(w http.ResponseWriter, r *http.Request) {
     if r.Method == "GET" {
         // Handle GET Request
@@ -130,59 +114,55 @@ func (db *Database) listHandler(w http.ResponseWriter, r *http.Request) {
         // If no parameter exists, retrieve all lists
         if param == nil || *param == "" {
             // Retrieve lists
-            list := getLists(db.Db)
+            list := getLists(db.Db, w)
             json.NewEncoder(w).Encode(&list)
         } else {
             // Get the list id from the parameter
             listId, err := strconv.Atoi(*param)
-            CheckFatal(err)
+            CheckFatal(err, w)
 
             // Retrieve tasks and send them back
-            tasks := getTasks(db.Db, listId)
+            tasks := getTasks(db.Db, listId, w)
             json.NewEncoder(w).Encode(&tasks)
         }
     } else if r.Method == "POST" {
         // Parse the request and create a new list
         body, err := ioutil.ReadAll(r.Body)
-        CheckFatal(err)
+        CheckFatal(err, w)
         listRequest := ListCreateRequest{}
         err = json.Unmarshal(body, &listRequest)
-        CheckFatal(err)
+        CheckFatal(err, w)
 
         listResponse := ListCreateResponse{}
-        listResponse.Id = insertList(db.Db, listRequest.Name)
+        listResponse.Id = insertList(db.Db, listRequest.Name, w)
 
         json.NewEncoder(w).Encode(&listResponse)
     }
 }
 
-// taskHandler manages requests with regards to the tasks.
-// A POST request to /task will create a new task with the name and list provided in
-// the Post Body. The Body should be in the format {"name": "taskName", "list_id": 123}
 func (db *Database) taskHandler(w http.ResponseWriter, r *http.Request) {
     if r.Method == "POST" {
         body, err := ioutil.ReadAll(r.Body)
-        CheckFatal(err)
+        CheckFatal(err, w)
         taskRequest := CreateTaskRequest{}
         err = json.Unmarshal(body, &taskRequest)
-        CheckFatal(err)
+        CheckFatal(err, w)
 
-        insertTask(db.Db, taskRequest.Name, taskRequest.ListId)
+        insertTask(db.Db, taskRequest.Name, taskRequest.ListId, w)
 
         fmt.Fprintf(w, "OK")
     }
 }
 
-// ConnectDb connects to a postgres database.
-// it returns a database handle
 func ConnectDb() *sql.DB {
     db, err := sql.Open("postgres", "postgres://simon@localhost/todo?sslmode=disable")
-    CheckFatal(err)
+    if err != nil {
+        log.Fatal(err)
+    }
 
     return db
 }
 
-// Handlers retrieves all handlers for the server.
 func Handlers() *http.ServeMux {
     db := Database{Db: ConnectDb()}
     mux := http.NewServeMux()
@@ -195,5 +175,7 @@ func Handlers() *http.ServeMux {
 func main() {
     // Listen on port 5050
     err := http.ListenAndServe(":5050", Handlers())
-    CheckFatal(err)
+    if err != nil {
+        log.Fatal(err)
+    }
 }