Clear omitted bindData fields when nullMissing is enabled

grails-databinding-core/src/main/groovy/grails/databinding/SimpleDataBinder.groovy

@@ -271,7 +271,23 @@ class SimpleDataBinder implements DataBinder {
     }
 
     protected boolean isOkToBind(String propName, List whiteList, List blackList) {
-        'class' != propName && 'classLoader' != propName && 'protectionDomain' != propName && 'metaClass' != propName && 'metaPropertyValues' != propName && 'properties' != propName && !blackList?.contains(propName) && (whiteList == null || isBindAllBindingIncludeList(whiteList) || whiteList.contains(propName) || whiteList.find { it -> it?.toString()?.startsWith(propName + '.') })
+        !isFrameworkProperty(propName) && !blackList?.contains(propName) &&
+                (whiteList == null || isBindAllBindingIncludeList(whiteList) || whiteList.contains(propName) ||
+                        whiteList.any { item -> item?.toString()?.startsWith(propName + '.') })
+    }
+
+    static boolean isPropertyExcluded(String propertyName, List excludeList) {
+        excludeList?.any { item ->
+            String excludeName = item?.toString()
+            excludeName == propertyName || propertyName.startsWith(excludeName + '.') ||
+                    (excludeName?.endsWith('.*') && propertyName.startsWith(excludeName.substring(0, excludeName.length() - 1))) ||
+                    (excludeName?.endsWith('_*') && propertyName.startsWith(excludeName.substring(0, excludeName.length() - 1)))
+        } ?: false
+    }
+
+    private static boolean isFrameworkProperty(String propertyName) {
+        'class' == propertyName || 'classLoader' == propertyName || 'protectionDomain' == propertyName ||
+                'metaClass' == propertyName || 'metaPropertyValues' == propertyName || 'properties' == propertyName
     }
 
     protected static List getBindAllBindingIncludeList() {

grails-doc/src/en/guide/upgrading/upgrading80x.adoc

@@ -825,6 +825,9 @@ The Spring annotations still work, so this is non-blocking, but new code should
 * **Namespaced link generation is namespace-aware.**
 When a link, form action, pagination link, sortable column link, redirect, chain, or include targets a controller without an explicit `namespace`, Grails now resolves the namespace automatically. In the normal case, where only one controller has the target name, `controller` and `action` generate the correct namespaced or non-namespaced URL. Ambiguity only occurs when multiple controllers share the same name. In that case, specify `namespace` to choose the target explicitly. Pass `namespace: null` from Groovy code or `namespace=""` in a GSP tag to target the non-namespaced controller explicitly.
 
+* **`bindData` can clear omitted included fields.**
+`bindData(target, source, [include: [...], nullMissing: true])` now assigns `null` to included properties that are absent from the binding source. The behavior is opt-in, requires an `include` list, and does not apply globally. Existing `bindData` calls without `nullMissing: true` keep omitted fields unchanged.
+
 ==== 21. Tag Library Test Cleanup Changes
 
 Grails 8 removes the `purgeTagLibMetaClass` test hook used by some web and TagLib unit tests.

grails-doc/src/en/ref/Controllers/bindData.adoc

@@ -45,6 +45,9 @@ bindData(target, params, [exclude: ['firstName', 'lastName']], "author")
 
 // using inclusive map
 bindData(target, params, [include: ['firstName', 'lastName']], "author")
+
+// clear included properties omitted from the source
+bindData(target, params, [include: ['firstName', 'lastName'], nullMissing: true])
 ----
 
 
@@ -57,7 +60,7 @@ Arguments:
 
 * `target` - The target object to bind to
 * `params` - A `Map` of source parameters, often the link:params.html[params] object when used in a controller
-* `includesExcludes` - (Optional) A map with 'include' and/or 'exclude' lists containing the names of properties to either include or exclude.
+* `includesExcludes` - (Optional) A map with 'include' and/or 'exclude' lists containing the names of properties to either include or exclude. Set `nullMissing: true` with an `include` list to assign `null` to included properties that are omitted from the binding source.
 * `prefix` - (Optional) A string representing a prefix to use to filter parameters. The method will automatically append a '.' when matching the prefix to parameters, so you can use 'author' to filter for parameters such as 'author.name'.
 
 If no `include` list is supplied, `bindData` uses the target class default binding behavior.  By default, statically typed instance properties bind for compatibility unless they are marked `bindable: false`.  Existing `bindable: true` declarations and explicit `include` lists continue to bind exactly the properties they name without configuration changes.  An empty `include` list binds no properties.
@@ -84,6 +87,8 @@ class PersonController {
 
 See the link:{constraintsRefFromRef}bindable.html[bindable] constraint documentation for more information on controlling default bindability.  Applications may set `grails.databinding.legacyBindableDefault=false` to opt into deny-by-default binding allowlists.  In secure mode, permit a property with `bindable: true`, an explicit `include` list, or `@BindAllowed` on a controller action command object parameter.
 
+`nullMissing` is opt-in and only applies when an `include` list is provided. This is useful for update forms where an omitted allowed field should clear an existing value instead of leaving stale persisted data. Excluded properties are not cleared.
+
 The underlying implementation uses Spring's Data Binding framework. If the target is a domain class, type conversion errors are stored in the `errors` property of the domain class.
 
 Refer to the section on link:{guidePath}theWebLayer.html#dataBinding[data binding] in the user guide for more information.

grails-test-suite-web/src/test/groovy/org/grails/web/binding/DefaultASTDatabindingHelperDomainClassSpecialPropertiesSpec.groovy

@@ -18,6 +18,7 @@
  */
 package org.grails.web.binding
 
+import grails.config.Config
 import grails.gorm.dirty.checking.DirtyCheck
 import grails.persistence.Entity
 import grails.util.Holders
@@ -26,11 +27,19 @@ import org.grails.config.PropertySourcesConfig
 import org.grails.validation.ConstraintEvalUtils
 import org.grails.web.databinding.DefaultASTDatabindingHelper
 import spock.lang.Issue
+import spock.lang.Shared
 import spock.lang.Specification
 
 class DefaultASTDatabindingHelperDomainClassSpecialPropertiesSpec extends
         Specification {
 
+    @Shared
+    Config originalConfig
+
+    def setupSpec() {
+        originalConfig = Holders.config
+    }
+
     def setup() {
         ConstraintEvalUtils.clearDefaultConstraints()
         Holders.setConfig(new PropertySourcesConfig([(DefaultASTDatabindingHelper.LEGACY_BINDABLE_DEFAULT): false]))
@@ -40,6 +49,11 @@ class DefaultASTDatabindingHelperDomainClassSpecialPropertiesSpec extends
         ConstraintEvalUtils.clearDefaultConstraints()
     }
 
+    def cleanupSpec() {
+        ConstraintEvalUtils.clearDefaultConstraints()
+        Holders.setConfig(originalConfig)
+    }
+
     @Issue('GRAILS-11173')
     void 'Test binding to special properties in a domain class'() {
         when: