04 - Validation: Create Custom Constraint

src/main/java/de/schulung/quarkus/recipes/Recipe.java

@@ -4,7 +4,6 @@
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotNull;
-import jakarta.validation.constraints.Pattern;
 import jakarta.validation.constraints.Size;
 import lombok.Getter;
 import lombok.Setter;
@@ -30,8 +29,7 @@ public class Recipe {
   /**
    * URL of the recipe image, absolute or relative.
    */
-  @Size(max = 255)
-  @Pattern(regexp = "^(/|https?://).+")
+  @ValidUrl
   private String img;
   /**
    * The number of servings.

src/main/java/de/schulung/quarkus/recipes/ValidUrl.java

@@ -0,0 +1,32 @@
+package de.schulung.quarkus.recipes;
+
+import jakarta.validation.Constraint;
+import jakarta.validation.Payload;
+import jakarta.validation.ReportAsSingleViolation;
+import jakarta.validation.constraints.Pattern;
+import jakarta.validation.constraints.Size;
+
+import java.lang.annotation.*;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target({
+  ElementType.METHOD,
+  ElementType.FIELD,
+  ElementType.PARAMETER,
+  ElementType.ANNOTATION_TYPE,
+  ElementType.CONSTRUCTOR,
+  ElementType.TYPE_USE
+})
+@Documented
+@Constraint(validatedBy = {})
+@Size(max = 255)
+@Pattern(regexp = "^(/|https?://).+")
+@ReportAsSingleViolation
+public @interface ValidUrl {
+
+  String message() default "must be a valid image URL (absolute or starting with /) with at most 255 characters";
+
+  Class<?>[] groups() default {};
+
+  Class<? extends Payload>[] payload() default {};
+}