adds validation to the json

cmd/api/helpers.go

@@ -7,7 +7,6 @@ import (
 	"io"
 	"net/http"
 	"strconv"
-	"strings"
 
 	"github.com/julienschmidt/httprouter"
 )
@@ -15,56 +14,51 @@ import (
 type envelope map[string]any
 
 func (app *application) readJSON(w http.ResponseWriter, r *http.Request, dest any) error {
+
 	maxBytes := 1_048_576
 	r.Body = http.MaxBytesReader(w, r.Body, int64(maxBytes))
 
-	decoder := json.NewDecoder(r.Body)
-	decoder.DisallowUnknownFields()
-
-	err := decoder.Decode(dest)
+	dec := json.NewDecoder(r.Body)
+	dec.DisallowUnknownFields()
 
+	err := dec.Decode(dest)
 	if err != nil {
 		var syntaxError *json.SyntaxError
-		var unmarshallError *json.UnmarshalTypeError
-		var invalidUnmarshall *json.InvalidUnmarshalError
-		var maxBytesError *http.MaxBytesError
+		var unmarshalTypeError *json.UnmarshalTypeError
+		var invalidUnmarshalError *json.InvalidUnmarshalError
 
 		switch {
 		case errors.As(err, &syntaxError):
-			return fmt.Errorf("body contains badly-formed JSON (at character %d)", syntaxError.Offset)
+			return fmt.Errorf("body contains badly-formatted JSON (at character %d)", syntaxError.Offset)
 
 		case errors.Is(err, io.ErrUnexpectedEOF):
 			return errors.New("body contains badly-formed JSON")
 
-		case errors.As(err, &unmarshallError):
-			if unmarshallError.Field != "" {
-				return fmt.Errorf("the body contains incorrect json type for field %q", unmarshallError.Field)
+		case errors.As(err, &unmarshalTypeError):
+			if unmarshalTypeError.Field != "" {
+				return fmt.Errorf("body contains incorrect JOSN type for field %q", unmarshalTypeError.Field)
 			}
-			return fmt.Errorf("body contains incorrect JSON type (at character %d)", unmarshallError.Offset)
+
+			return fmt.Errorf("body contains incorrect JOSN type (at character %d)", unmarshalTypeError.Offset)
 
 		case errors.Is(err, io.EOF):
 			return errors.New("body must not be empty")
 
-		case strings.HasPrefix(err.Error(), "json: unknown field "):
-			fieldName := strings.TrimPrefix(err.Error(), "json: unknown field ")
-			return fmt.Errorf("body contains uknown key %s", fieldName)
-
-		case errors.As(err, &maxBytesError):
-			return fmt.Errorf("body must not be larger than %d bytes", maxBytesError.Limit)
-
-		case errors.As(err, &invalidUnmarshall):
+		case errors.As(err, &invalidUnmarshalError):
 			panic(err)
 
 		default:
 			return err
+
 		}
 	}
-	err = decoder.Decode(&struct{}{})
+
+	err = dec.Decode(&struct{}{})
 	if err != io.EOF {
-		return errors.New("body must only contain a single JSON value")
+		return errors.New("body must only contain a single json value")
 	}
 
-	return nil // no errors
+	return nil
 }
 
 func (app *application) readIDParam(r *http.Request) (int64, error) {

cmd/api/movies.go

@@ -10,19 +10,19 @@ import (
 
 func (app *application) createMovieHandler(w http.ResponseWriter, r *http.Request) {
 	var input struct {
-		Title   string   `json:"title"`
-		Year    int32    `json:"year"`
-		Runtime int32    `json:"runtime"`
-		Genres  []string `json:"genres"`
+		Title   string       `json:"title"`
+		Year    int32        `json:"year"`
+		Runtime data.Runtime `json:"runtime"`
+		Genres  []string     `json:"genres"`
 	}
 
 	err := app.readJSON(w, r, &input)
 	if err != nil {
-		app.badRequestResponse(w, r, err)
+		app.errorResponse(w, r, http.StatusBadRequest, err.Error())
 		return
 	}
 
-	fmt.Fprintf(w, "%v+\n", input)
+	fmt.Fprintf(w, "%+v\n", input)
 }
 
 func (app *application) showMovieHandler(w http.ResponseWriter, r *http.Request) {

go.mod

@@ -1,5 +1,5 @@
 module greenlight.ergz
 
-go 1.20
+go 1.21
 
 require github.com/julienschmidt/httprouter v1.3.0 // indirect

internal/data/runtime.go

@@ -1,10 +1,14 @@
 package data
 
 import (
+	"errors"
 	"fmt"
 	"strconv"
+	"strings"
 )
 
+var ErrInvalidRuntimeFormat = errors.New("invalid runtime format, should be something like '102 mins'")
+
 type Runtime int32
 
 func (r Runtime) MarshalJSON() ([]byte, error) {
@@ -14,3 +18,25 @@ func (r Runtime) MarshalJSON() ([]byte, error) {
 	return []byte(quotedJSONValue), nil
 
 }
+
+func (r *Runtime) UnmarshalJSON(jsonValue []byte) error {
+	unquoJSONValue, err := strconv.Unquote(string(jsonValue))
+	if err != nil {
+		return ErrInvalidRuntimeFormat
+	}
+
+	jsonParts := strings.Split(unquoJSONValue, " ")
+
+	if len(jsonParts) != 2 || (jsonParts[1] != "mins" && jsonParts[1] != "minutes") {
+		return ErrInvalidRuntimeFormat
+	}
+
+	i, err := strconv.ParseInt(jsonParts[0], 10, 32)
+	if err != nil {
+		return ErrInvalidRuntimeFormat
+	}
+
+	*r = Runtime(i)
+
+	return nil
+}

internal/validator/validator.go

@@ -0,0 +1,55 @@
+package validator
+
+import "regexp"
+
+var (
+	EmailRX = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}")
+)
+
+type Validator struct {
+	Errors map[string]string
+}
+
+func New() *Validator {
+	return &Validator{Errors: make(map[string]string)}
+}
+
+func (v *Validator) Valid() bool {
+	return len(v.Errors) == 0
+}
+
+func (v *Validator) AddError(key, message string) {
+	if _, exists := v.Errors[key]; !exists {
+		v.Errors[key] = message
+	}
+}
+
+func (v *Validator) Check(ok bool, key string, message string) {
+	if !ok {
+		v.AddError(key, message)
+	}
+}
+
+func PermittedValue[T comparable](value T, permittedValues ...T) bool {
+	for i := range permittedValues {
+		if value == permittedValues[i] {
+			return true
+		}
+	}
+
+	return false
+}
+
+func Matches(value string, rx *regexp.Regexp) bool {
+	return rx.MatchString(value)
+}
+
+func Unique[T comparable](values []T) bool {
+	uniqueValues := make(map[T]bool)
+
+	for _, value := range values {
+		uniqueValues[value] = true
+	}
+
+	return len(values) == len(uniqueValues)
+}