GH-1 add a not null validator

jackson-merge-patch-validations/src/main/java/com/github/jeffnelson/jackson/patch/validator/PatchNotNullValidator.java

@@ -0,0 +1,25 @@
+
+package com.github.jeffnelson.jackson.patch.validator;
+
+import javax.validation.ConstraintValidator;
+import javax.validation.ConstraintValidatorContext;
+
+import com.github.jeffnelson.jackson.patch.PatchField;
+import com.github.jeffnelson.jackson.patch.validator.constraints.PatchNotNull;
+
+public class PatchNotNullValidator implements ConstraintValidator<PatchNotNull,PatchField<?>> {
+
+    @Override
+    public void initialize(PatchNotNull constraintAnnotation) {
+        // noop
+    }
+
+    @Override
+    public boolean isValid(PatchField<?> value, ConstraintValidatorContext context) {
+        if (value.shouldPatch()) {
+            return value.getValue() != null;
+        }
+        return true;
+    }
+
+}

jackson-merge-patch-validations/src/main/java/com/github/jeffnelson/jackson/patch/validator/PatchStringValidator.java

@@ -7,14 +7,14 @@
 import org.apache.commons.lang3.StringUtils;
 
 import com.github.jeffnelson.jackson.patch.PatchField;
-import com.github.jeffnelson.jackson.patch.validator.constraints.PatchStringValid;
+import com.github.jeffnelson.jackson.patch.validator.constraints.PatchStringRequired;
 
-public class PatchStringValidator implements ConstraintValidator<PatchStringValid,PatchField<String>> {
+public class PatchStringValidator implements ConstraintValidator<PatchStringRequired,PatchField<String>> {
 
     boolean allowNull, allowEmpty, allowBlank;
 
     @Override
-    public void initialize(PatchStringValid anno) {
+    public void initialize(PatchStringRequired anno) {
         this.allowNull = anno.allowNull();
         this.allowEmpty = anno.allowEmpty();
         this.allowBlank = anno.allowBlank();

jackson-merge-patch-validations/src/main/java/com/github/jeffnelson/jackson/patch/validator/constraints/PatchNotNull.java

@@ -0,0 +1,34 @@
+
+package com.github.jeffnelson.jackson.patch.validator.constraints;
+
+import static java.lang.annotation.ElementType.FIELD;
+import static java.lang.annotation.RetentionPolicy.RUNTIME;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.Target;
+
+import javax.validation.Constraint;
+import javax.validation.Payload;
+
+import com.github.jeffnelson.jackson.patch.PatchField;
+import com.github.jeffnelson.jackson.patch.validator.PatchNotNullValidator;
+
+/**
+ * Annotation to apply validation to {@literal PatchField<String>}
+ * <p>
+ * Default behavior. If {@link PatchField#shouldPatch()} returns true, value cannot be null
+ * 
+ * @author jeff.nelson
+ *
+ */
+@Constraint(validatedBy = PatchNotNullValidator.class)
+@Retention(RUNTIME)
+@Target(FIELD)
+public @interface PatchNotNull {
+
+    String message() default "Required";
+
+    Class<?>[] groups() default {};
+
+    Class<? extends Payload>[] payload() default {};
+}

jackson-merge-patch-validations/src/main/java/com/github/jeffnelson/jackson/patch/validator/constraints/PatchStringValid.java → jackson-merge-patch-validations/src/main/java/com/github/jeffnelson/jackson/patch/validator/constraints/PatchStringRequired.java

@@ -29,7 +29,7 @@
 @Constraint(validatedBy = PatchStringValidator.class)
 @Retention(RUNTIME)
 @Target(FIELD)
-public @interface PatchStringValid {
+public @interface PatchStringRequired {
 
     String message() default "Required";
 

jackson-merge-patch-validations/src/test/java/com/github/jeffnelson/jackson/patch/validator/PatchNotNullValidatorTest.java

@@ -0,0 +1,38 @@
+
+package com.github.jeffnelson.jackson.patch.validator;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.github.jeffnelson.jackson.patch.PatchField;
+
+public class PatchNotNullValidatorTest {
+
+    private PatchNotNullValidator validator;
+
+    @Before
+    public void setup() {
+        validator = new PatchNotNullValidator();
+    }
+
+    @Test
+    public void testNoPatch() {
+        PatchField<String> value = PatchField.<String> builder().shouldPatch(false).build();
+        assertTrue(validator.isValid(value, null));
+    }
+
+    @Test
+    public void testPatch_helloWorld() {
+        PatchField<String> value = PatchField.<String> builder().shouldPatch(true).value("hello, world").build();
+        assertTrue(validator.isValid(value, null));
+    }
+
+    @Test
+    public void testPatch_null() {
+        PatchField<String> value = PatchField.<String> builder().shouldPatch(true).value(null).build();
+        assertFalse(validator.isValid(value, null));
+    }
+}