Make domain properties nullable by default (Grails 8)

grails-core/src/main/groovy/grails/config/Settings.groovy

@@ -151,6 +151,11 @@ interface Settings {
      */
     String GORM_DEFAULT_CONSTRAINTS = 'grails.gorm.default.constraints'
 
+    /**
+     * Whether an unconstrained persistent property is nullable by default
+     */
+    String GORM_DEFAULT_NULLABLE = 'grails.gorm.default.nullable'
+
     /**
      * Whether to autowire instances
      */

grails-core/src/main/groovy/org/grails/validation/ConstraintEvalUtils.groovy

@@ -61,6 +61,14 @@ class ConstraintEvalUtils {
         return defaultConstraintsMap
     }
 
+    /**
+     * Whether an unconstrained persistent property is nullable by default (Grails 8).
+     * Set {@code grails.gorm.default.nullable = false} to restore the legacy required-by-default behaviour.
+     */
+    static boolean getDefaultNullable(Config config) {
+        config.getProperty(Settings.GORM_DEFAULT_NULLABLE, Boolean, true)
+    }
+
     static void clearDefaultConstraints() {
         defaultConstraintsMap =  null
         configId = null

grails-core/src/main/resources/META-INF/spring-configuration-metadata.json

@@ -222,6 +222,12 @@
             "description": "A closure applied as the default constraints for all domain classes.",
             "defaultValue": {}
         },
+        {
+            "name": "grails.gorm.default.nullable",
+            "type": "java.lang.Boolean",
+            "description": "Whether an unconstrained persistent property is nullable by default (Grails 8). Set to false to restore the legacy required-by-default behaviour.",
+            "defaultValue": true
+        },
         {
             "name": "grails.gorm.custom.types",
             "type": "java.util.Map<java.lang.String,java.lang.Object>",

grails-data-hibernate5/core/src/test/groovy/grails/gorm/tests/SaveWithExistingValidationErrorSpec.groovy

@@ -66,5 +66,6 @@ class ObjectB {
     String name
 
     static constraints = {
+        name nullable: false
     }
 }

grails-data-hibernate5/core/src/test/groovy/grails/gorm/tests/entities/Contract.groovy

@@ -28,4 +28,8 @@ import grails.gorm.annotation.Entity
 class Contract {
     BigDecimal salary
     static belongsTo = [player: Player]
+
+    static constraints = {
+        player nullable: false
+    }
 }

grails-data-hibernate5/core/src/test/groovy/grails/gorm/tests/validation/CascadeValidationSpec.groovy

@@ -61,6 +61,9 @@ class Business {
             people: Person
     ]
 
+    static constraints = {
+        name nullable: false
+    }
 }
 @Entity
 abstract class Person {

grails-data-hibernate5/grails-plugin/src/test/groovy/grails/test/mixin/hibernate/HibernateSpecSpec.groovy

@@ -73,7 +73,7 @@ class Person {
     Integer age
     String phone
     static constraints = {
-        age min: 18, max: 65
+        age min: 18, max: 65, nullable: false
         name blank: false
         phone nullable: true
     }

grails-data-hibernate7/core/src/test/groovy/grails/gorm/tests/SaveWithExistingValidationErrorSpec.groovy

@@ -66,5 +66,6 @@ class ObjectB {
     String name
 
     static constraints = {
+        name nullable: false
     }
 }

grails-data-hibernate7/core/src/test/groovy/grails/gorm/tests/entities/Contract.groovy

@@ -28,4 +28,8 @@ import grails.gorm.annotation.Entity
 class Contract {
     BigDecimal salary
     static belongsTo = [player: Player]
+
+    static constraints = {
+        player nullable: false
+    }
 }

grails-data-hibernate7/core/src/test/groovy/grails/gorm/tests/validation/CascadeValidationSpec.groovy

@@ -61,6 +61,9 @@ class Business {
             people: Person
     ]
 
+    static constraints = {
+        name nullable: false
+    }
 }
 @Entity
 abstract class Person {

grails-data-hibernate7/grails-plugin/src/test/groovy/grails/test/mixin/hibernate/HibernateSpecSpec.groovy

@@ -73,7 +73,7 @@ class Person {
     Integer age
     String phone
     static constraints = {
-        age min: 18, max: 65
+        age min: 18, max: 65, nullable: false
         name blank: false
         phone nullable: true
     }

grails-data-mongodb/core/src/test/groovy/grails/gorm/tests/Plant.groovy

@@ -28,6 +28,10 @@ class Plant implements Serializable, MongoEntity<Plant> {
     boolean goesInPatch
     String name
 
+    static constraints = {
+        name nullable: false
+    }
+
     static mapping = {
         name index:true
         goesInPatch index:true

grails-data-mongodb/core/src/test/groovy/grails/mongodb/bootstrap/MongoDbDataStoreSpringInitializerSpec.groovy

@@ -226,7 +226,7 @@ class Person implements MongoEntity<Person> {
     Birthday birthday
 
     static constraints = {
-        name blank: false
+        name blank: false, nullable: false
         birthday nullable: true
     }
 }

grails-data-mongodb/core/src/test/groovy/org/grails/datastore/gorm/mongo/FindOrCreateWhereSpec.groovy

@@ -18,6 +18,7 @@
  */
 package org.grails.datastore.gorm.mongo
 
+import grails.gorm.tests.Person
 import grails.gorm.tests.Pet
 import org.apache.grails.data.mongo.core.GrailsDataMongoTckManager
 import org.apache.grails.data.testing.tck.base.GrailsDataTckSpec

grails-datamapping-core-test/src/test/groovy/grails/gorm/tests/CircularCascadeSpec.groovy

@@ -133,10 +133,18 @@ class SportValidate {
 class TeamValidate {
 
     String name
+
+    static constraints = {
+        name nullable: false
+    }
 }
 
 @Entity
 class ArenaValidate {
 
     String name
+
+    static constraints = {
+        name nullable: false
+    }
 }

grails-datamapping-tck/src/main/groovy/org/apache/grails/data/testing/tck/domains/ClassWithListArgBeforeValidate.groovy

@@ -36,6 +36,6 @@ class ClassWithListArgBeforeValidate implements Serializable {
     }
 
     static constraints = {
-        name(blank: false)
+        name(blank: false, nullable: false)
     }
 }

grails-datamapping-tck/src/main/groovy/org/apache/grails/data/testing/tck/domains/ClassWithNoArgBeforeValidate.groovy

@@ -34,6 +34,6 @@ class ClassWithNoArgBeforeValidate implements Serializable {
     }
 
     static constraints = {
-        name(blank: false)
+        name(blank: false, nullable: false)
     }
 }

grails-datamapping-tck/src/main/groovy/org/apache/grails/data/testing/tck/domains/ClassWithOverloadedBeforeValidate.groovy

@@ -41,6 +41,6 @@ class ClassWithOverloadedBeforeValidate implements Serializable {
     }
 
     static constraints = {
-        name(blank: false)
+        name(blank: false, nullable: false)
     }
 }

grails-datamapping-validation/src/main/groovy/org/grails/datastore/gorm/validation/constraints/eval/DefaultConstraintEvaluator.java

@@ -72,6 +72,7 @@ public class DefaultConstraintEvaluator implements ConstraintsEvaluator {
     protected final MappingContext mappingContext;
     protected final Map<String, Object> defaultConstraints;
     protected final boolean cacheAutoTimestampAnnotations;
+    protected final boolean defaultNullable;
 
     public DefaultConstraintEvaluator() {
         this(new DefaultConstraintRegistry(new StaticMessageSource()), new KeyValueMappingContext("default"), Collections.<String, Object>emptyMap(), true);
@@ -98,10 +99,15 @@ public DefaultConstraintEvaluator(ConstraintRegistry constraintRegistry, Mapping
     }
 
     public DefaultConstraintEvaluator(ConstraintRegistry constraintRegistry, MappingContext mappingContext, Map<String, Object> defaultConstraints, boolean cacheAutoTimestampAnnotations) {
+        this(constraintRegistry, mappingContext, defaultConstraints, cacheAutoTimestampAnnotations, true);
+    }
+
+    public DefaultConstraintEvaluator(ConstraintRegistry constraintRegistry, MappingContext mappingContext, Map<String, Object> defaultConstraints, boolean cacheAutoTimestampAnnotations, boolean defaultNullable) {
         this.constraintRegistry = constraintRegistry;
         this.mappingContext = mappingContext;
         this.defaultConstraints = defaultConstraints;
         this.cacheAutoTimestampAnnotations = cacheAutoTimestampAnnotations;
+        this.defaultNullable = defaultNullable;
     }
 
     @Override
@@ -270,7 +276,14 @@ protected void applyDefaultConstraints(String propertyName, PersistentProperty p
     }
 
     protected void applyDefaultNullableConstraint(PersistentProperty p, ConstrainedProperty cp) {
-        applyDefaultNullableConstraint(cp, false);
+        // Grails 8: persistent properties are nullable by default, aligning Grails with the rest of
+        // the JVM persistence/validation ecosystem (JPA/Hibernate, Spring Data, Micronaut Data and
+        // Jakarta Bean Validation are all "nullable unless you say otherwise"). To restore the
+        // legacy required-by-default behavior, either set the boolean flag:
+        //     grails.gorm.default.nullable = false
+        // or apply a wildcard default constraint:
+        //     grails.gorm.default.constraints = { '*'(nullable: false) }
+        applyDefaultNullableConstraint(cp, defaultNullable);
     }
 
     protected void applyDefaultNullableConstraint(ConstrainedProperty cp, boolean defaultNullable) {

grails-datamapping-validation/src/main/groovy/org/grails/datastore/gorm/validation/constraints/registry/DefaultValidatorRegistry.groovy

@@ -60,7 +60,8 @@ class DefaultValidatorRegistry implements ValidatorRegistry, ConstraintRegistry,
         // Default to true if not explicitly configured
         boolean cacheAnnotations = connectionSourceSettings.cacheAutoTimestampAnnotations != null ?
             connectionSourceSettings.cacheAutoTimestampAnnotations : true
-        this.constraintsEvaluator = new DefaultConstraintEvaluator(constraintRegistry, mappingContext, defaultConstraintsMap, cacheAnnotations)
+        boolean defaultNullable = connectionSourceSettings.default.nullable
+        this.constraintsEvaluator = new DefaultConstraintEvaluator(constraintRegistry, mappingContext, defaultConstraintsMap, cacheAnnotations, defaultNullable)
         this.mappingContext = mappingContext
     }
 

grails-datamapping-validation/src/test/groovy/grails/gorm/validation/NullableByDefaultSpec.groovy

@@ -0,0 +1,121 @@
+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one
+ *  or more contributor license agreements.  See the NOTICE file
+ *  distributed with this work for additional information
+ *  regarding copyright ownership.  The ASF licenses this file
+ *  to you under the Apache License, Version 2.0 (the
+ *  "License"); you may not use this file except in compliance
+ *  with the License.  You may obtain a copy of the License at
+ *
+ *    https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing,
+ *  software distributed under the License is distributed on an
+ *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ *  KIND, either express or implied.  See the License for the
+ *  specific language governing permissions and limitations
+ *  under the License.
+ */
+package grails.gorm.validation
+
+import org.grails.datastore.gorm.validation.constraints.registry.DefaultValidatorRegistry
+import org.grails.datastore.mapping.core.connections.ConnectionSourceSettings
+import org.grails.datastore.mapping.keyvalue.mapping.config.GormKeyValueMappingFactory
+import org.grails.datastore.mapping.keyvalue.mapping.config.KeyValueMappingContext
+import org.grails.datastore.mapping.model.MappingContext
+import org.grails.datastore.mapping.model.PersistentEntity
+import org.grails.datastore.mapping.model.config.GormMappingConfigurationStrategy
+import org.grails.datastore.mapping.validation.ValidationErrors
+import org.grails.datastore.mapping.validation.ValidatorRegistry
+import org.springframework.validation.Errors
+import org.springframework.validation.Validator
+import spock.lang.Shared
+import spock.lang.Specification
+
+import jakarta.persistence.Entity
+
+/**
+ * Demonstrates the Grails 8 default: an unconstrained persistent property is nullable by default,
+ * aligning Grails with the rest of the JVM persistence/validation ecosystem. This spec deliberately
+ * does NOT opt out (no {@code grails.gorm.default.constraints} override), so it exercises the real
+ * framework default applied by {@code DefaultConstraintEvaluator}.
+ */
+class NullableByDefaultSpec extends Specification {
+
+    @Shared Validator widgetValidator
+
+    void setupSpec() {
+        MappingContext mappingContext = new KeyValueMappingContext("test")
+        mappingContext.mappingFactory = new GormKeyValueMappingFactory("test")
+        mappingContext.syntaxStrategy = new GormMappingConfigurationStrategy(mappingContext.mappingFactory)
+
+        PersistentEntity widgetEntity = mappingContext.addPersistentEntity(Widget)
+
+        ValidatorRegistry registry = new DefaultValidatorRegistry(mappingContext, new ConnectionSourceSettings())
+        widgetValidator = registry.getValidator(widgetEntity)
+    }
+
+    void "an unconstrained property is nullable by default"() {
+        given: "a widget whose only populated property is the explicitly-required one"
+        Widget widget = new Widget(requiredName: 'gizmo')
+        Errors errors = new ValidationErrors(widget)
+
+        when:
+        widgetValidator.validate(widget, errors)
+
+        then: "the unconstrained properties are valid while null - they are nullable by default"
+        !errors.hasErrors()
+        !errors.getFieldError('description')
+        !errors.getFieldError('quantity')
+    }
+
+    void "a property with an explicit nullable: false constraint is still required"() {
+        given: "a widget missing the explicitly-required property"
+        Widget widget = new Widget()
+        Errors errors = new ValidationErrors(widget)
+
+        when:
+        widgetValidator.validate(widget, errors)
+
+        then: "only the explicitly-required property is rejected; the unconstrained ones are not"
+        errors.hasErrors()
+        errors.getFieldError('requiredName')?.code == 'nullable'
+        !errors.getFieldError('description')
+        !errors.getFieldError('quantity')
+    }
+
+    void "grails.gorm.default.nullable = false restores required-by-default"() {
+        given: "a validator built with the YAML-friendly flag disabled"
+        MappingContext mappingContext = new KeyValueMappingContext("test")
+        mappingContext.mappingFactory = new GormKeyValueMappingFactory("test")
+        mappingContext.syntaxStrategy = new GormMappingConfigurationStrategy(mappingContext.mappingFactory)
+        PersistentEntity widgetEntity = mappingContext.addPersistentEntity(Widget)
+
+        ConnectionSourceSettings settings = new ConnectionSourceSettings()
+        settings.default.nullable = false
+        Validator validator = new DefaultValidatorRegistry(mappingContext, settings).getValidator(widgetEntity)
+
+        and: "a widget whose unconstrained properties are null"
+        Widget widget = new Widget(requiredName: 'gizmo')
+        Errors errors = new ValidationErrors(widget)
+
+        when:
+        validator.validate(widget, errors)
+
+        then: "the unconstrained properties are required again - the flag restored legacy behaviour"
+        errors.hasErrors()
+        errors.getFieldError('description')?.code == 'nullable'
+        errors.getFieldError('quantity')?.code == 'nullable'
+    }
+}
+
+@Entity
+class Widget {
+    String description
+    Integer quantity
+    String requiredName
+
+    static constraints = {
+        requiredName nullable: false
+    }
+}

grails-datamapping-validation/src/test/groovy/grails/gorm/validation/PersistentEntityValidatorSpec.groovy

@@ -200,6 +200,8 @@ class Author {
     ]
 
     static constraints = {
+        name(nullable: false)   // explicit now that properties are nullable by default — this spec
+                                // uses the null-name error to detect that root beforeValidate didn't run
         publisher(nullable: true)
         ownedPublisher(nullable: true)
         defaultPublisher(nullable: true)

grails-datastore-core/src/main/groovy/org/grails/datastore/mapping/core/connections/ConnectionSourceSettings.groovy

@@ -124,6 +124,12 @@ class ConnectionSourceSettings implements Settings {
          * The default constraints
          */
         Closure constraints
+
+        /**
+         * Whether an unconstrained persistent property is nullable by default (Grails 8 default: true).
+         * Set {@code grails.gorm.default.nullable = false} to restore the legacy required-by-default behaviour.
+         */
+        boolean nullable = true
     }
 
     /**