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=== Upgrade Instructions for Grails and Related Dependencies

To ensure compatibility with Grails 7.1.x, please review the following upgrade instructions carefully.
This guide outlines the necessary steps & warnings to upgrade your Grails project.

=== 1. Groovy Changes

The Grails Gradle Plugins now automatically disables invokedynamic for all `GroovyCompile` tasks (see https://github.com/apache/grails-core/issues/15293[#15293]). If you have a manual `tasks.withType(GroovyCompile)` block in your `build.gradle` that sets `indy = false`, you can safely remove it:

[source,groovy]
.build.gradle - remove this block (no longer needed)
----
  // This is now handled by the Grails Gradle Plugin - remove it
  tasks.withType(GroovyCompile).configureEach {
        groovyOptions.optimizationOptions.indy = false
  }
----

To re-enable invokedynamic, use the `grails` extension in your `build.gradle`:

[source,groovy]
.build.gradle
----
  grails {
      indy = true
  }
----

==== 2 Breaking changes

===== 2.1 Plugin configuration and Spring Conditional Annotations

Spring Boot's `@Configuration` related classes have support for conditional bean wiring. In prior versions of Grails, annotations such as `@ConditionalOnProperty` could not be used for configuration stored in a plugin's `plugin.groovy` or `plugin.yml` files. To support plugin configuration, plugin loading & configuration were split in Grails 7.1.x. Plugin loading related code was thus reworked and may break some applications if they relied on their own plugin loader.

WARNING: As a result of these changes, if your application extends the `GrailsApplicationPostProcessor` or `DefaultGrailsPluginManager` there are breaking constructor changes.
A new class, `PluginDiscovery`, was extracted from the Grails Plugin Manager logic and is now a dependency of these classes.

===== 2.2 Greedy Extension Parameter Matching in URL Mappings

Grails 7.1 introduces a new greedy extension parameter marker (`+`) for URL mappings that provides more intuitive handling of file extensions in URLs with multiple dots.

====== The Problem with Default Behavior

By default, Grails URL mappings with optional extensions split at the **first** dot in the path:

[source,groovy]
----
"/$id(.$format)?"(controller: 'user', action: 'profile')
----

When matching the URL `/test.test.json`:
- `id` = `test` (stops at first dot)
- `format` = `test.json` (everything after first dot)

This can be problematic when IDs legitimately contain dots, such as file names, qualified class names, or version numbers.

====== New Greedy Matching Behavior

The new `+` marker enables **greedy** matching, which splits at the **last** dot instead:

[source,groovy]
----
"/$id+(.$format)?"(controller: 'user', action: 'profile')
----

Now the same URL `/test.test.json` matches as:
- `id` = `test.test` (everything up to last dot)
- `format` = `json` (extension after last dot)

====== Syntax

The `+` marker is added after the variable name and before the optional marker:

**Required parameter with greedy extension:**
[source,groovy]
----
"/$id+(.$format)?"(controller: 'file', action: 'download')
----

**Optional parameter with greedy extension:**
[source,groovy]
----
"/$id+?(.$format)?"(controller: 'resource', action: 'show')
----

====== Use Cases

Greedy extension matching is particularly useful for:

1. **File downloads with complex names:**
+
[source,groovy]
----
"/files/$filename+(.$format)?"(controller: 'file', action: 'download')
----
+
Matches `/files/document.final.v2.pdf` → `filename=document.final.v2`, `format=pdf`

2. **Versioned resources:**
+
[source,groovy]
----
"/api/$resource+(.$format)?"(controller: 'api', action: 'show')
----
+
Matches `/api/user.service.v1.json` → `resource=user.service.v1`, `format=json`

3. **Qualified class names:**
+
[source,groovy]
----
"/docs/$className+(.$format)?"(controller: 'documentation', action: 'show')
----
+
Matches `/docs/com.example.MyClass.html` → `className=com.example.MyClass`, `format=html`

====== Behavior Details

- **With dots:** The greedy marker splits at the **last** dot, treating everything before as the parameter value and everything after as the extension
- **Without dots:** URLs without any dots match entirely as the parameter with no format
- **Extension optional:** When the extension is marked optional `(.$format)?`, URLs work both with and without extensions

**Examples:**

[source,groovy]
----
"/$id+(.$format)?"(controller: 'resource', action: 'show')

// URL Matches:
/test.test.json    → id='test.test', format='json'
/test.json         → id='test', format='json'
/simpletest        → id='simpletest', format=null
/foo.bar.baz.xml   → id='foo.bar.baz', format='xml'
----

====== Backward Compatibility

The `+` marker is opt-in and fully backward compatible:

- Existing URL mappings without the `+` marker continue to work as before (splitting at the first dot)
- No changes are required to existing applications
- The feature can be adopted incrementally on a per-mapping basis

===== 2.3 GormService API Changes

The `grails.plugin.scaffolding.GormService` class has been updated to fix a thread-safety issue and improve API clarity.

====== Changes

1. The `resource` field type changed from `GormAllOperations<T>` to `Class<T>`
2. A new `gormStaticApi` field of type `GormAllOperations<T>` was added with thread-safe lazy initialization using `@Lazy`
3. The constructor no longer instantiates the resource class - it now stores the Class reference directly

====== Migration Impact

If your code extends `GormService` or accesses its fields:

**Accessing GORM operations**: Previously the `resource` field provided GORM operations. Now use the `gormStaticApi` field instead:

[source,groovy]
----
// Before (7.1.x and earlier)
class MyService extends GormService<MyDomain> {
    void myMethod() {
        def result = resource.list()  // resource was GormAllOperations<T>
        // ...
    }
}

// After (7.1.x with fix)
class MyService extends GormService<MyDomain> {
    void myMethod() {
        def result = gormStaticApi.list()  // use gormStaticApi instead
        // ...
    }
}
----

**Accessing the domain class**: If you need the Class reference, the `resource` field is now properly typed as `Class<T>`:

[source,groovy]
----
// Before
Class<MyDomain> clazz = resource.getClass()  // awkward, resource was an instance

// After
Class<MyDomain> clazz = resource  // resource is now the Class itself
----

===== 2.4 Enhanced Audit Metadata Support

Grails 7.1 introduces comprehensive audit metadata support with new annotations for tracking both temporal information (when changes occurred) and auditor information (who made changes). This aligns with Spring Data's auditing model while maintaining GORM's flexibility.

====== New Annotations

Four new annotations have been added to simplify audit tracking:

* `@CreatedDate` - Automatically populated with the creation timestamp on insert
* `@LastModifiedDate` - Automatically populated with the modification timestamp on insert and update
* `@CreatedBy` - Automatically populated with the current auditor on insert
* `@LastModifiedBy` - Automatically populated with the current auditor on insert and update

These annotations work with various temporal types including `Date`, `LocalDateTime`, `Instant`, `OffsetDateTime`, and `ZonedDateTime`.

====== Example Domain Class

[source,groovy]
----
import grails.gorm.annotation.CreatedBy
import grails.gorm.annotation.CreatedDate
import grails.gorm.annotation.LastModifiedBy
import grails.gorm.annotation.LastModifiedDate
import java.time.LocalDateTime

class Book {
    String title
    String author

    @CreatedDate
    LocalDateTime created

    @LastModifiedDate
    LocalDateTime modified

    @CreatedBy
    String createdBy

    @LastModifiedBy
    String modifiedBy

    static constraints = {
        title blank: false
        author blank: false
        // Auditor fields should be nullable for anonymous operations
        createdBy nullable: true
        modifiedBy nullable: true
    }
}
----

====== Configuring AuditorAware

To populate `@CreatedBy` and `@LastModifiedBy` fields, you need to provide an `AuditorAware` bean that returns the current auditor:

[source,groovy]
.src/main/groovy/com/example/SpringSecurityAuditorAware.groovy
----
package com.example

import groovy.transform.CompileStatic
import org.grails.datastore.gorm.timestamp.AuditorAware
import org.springframework.security.core.Authentication
import org.springframework.security.core.context.SecurityContextHolder

@CompileStatic
class SpringSecurityAuditorAware implements AuditorAware<String> {

    @Override
    Optional<String> getCurrentAuditor() {
        Authentication authentication = SecurityContextHolder.getContext()
                                                              .getAuthentication()

        if (authentication == null || !authentication.isAuthenticated()) {
            return Optional.empty()
        }

        String username = authentication.getName()

        // Don't set auditor for anonymous users
        if (username == 'anonymousUser') {
            return Optional.empty()
        }

        return Optional.of(username)
    }
}
----

Register the bean in your `Application.groovy`:

[source,groovy]
.grails-app/init/com/example/Application.groovy
----
import org.grails.datastore.gorm.timestamp.AuditorAware
import org.springframework.context.annotation.Bean

class Application extends GrailsAutoConfiguration {
    static void main(String[] args) {
        GrailsApp.run(Application, args)
    }

    @Bean
    AuditorAware<String> auditorAware() {
        return new SpringSecurityAuditorAware()
    }
}
----

====== Auditor Field Types

Auditor fields can be different types depending on your needs:

* `String` - for username strings
* `Long` - for user ID references
* Custom types - for embedding user objects

Example with different auditor types:

[source,groovy]
----
class Document {
    String title

    @CreatedDate
    LocalDateTime created

    @CreatedBy
    String createdByUsername  // Store username as String

    @LastModifiedBy
    Long lastModifiedById     // Store user ID as Long

    static constraints = {
        createdByUsername nullable: true
        lastModifiedById nullable: true
    }
}
----

====== Constraints on Auditor Fields

Unlike timestamp fields, auditor fields can have constraints applied to them. This is useful for:

* Setting `maxSize` on String auditors to match database column definitions
* Applying validation rules
* Customizing database mapping

[source,groovy]
----
class Task {
    String name

    @CreatedBy
    String createdBy

    @LastModifiedBy
    String modifiedBy

    static constraints = {
        name blank: false
        // Apply constraints to auditor fields
        createdBy nullable: true, maxSize: 100
        modifiedBy nullable: true, maxSize: 100
    }
}
----

====== Deprecation of @AutoTimestamp

The `@AutoTimestamp` annotation is now deprecated in favor of the more explicit `@CreatedDate` and `@LastModifiedDate` annotations:

[source,groovy]
----
// Old (deprecated)
@AutoTimestamp(AutoTimestamp.EventType.CREATED)
LocalDateTime created

@AutoTimestamp
LocalDateTime modified

// New (recommended)
@CreatedDate
LocalDateTime created

@LastModifiedDate
LocalDateTime modified
----

The `@AutoTimestamp` annotation is marked with `@Deprecated(forRemoval = true)` and will be removed in Grails 8.0.

====== Migration Guide

To migrate from `@AutoTimestamp` to the new annotations:

1. Replace `@AutoTimestamp(AutoTimestamp.EventType.CREATED)` with `@CreatedDate`
2. Replace `@AutoTimestamp` (or `@AutoTimestamp(EventType.UPDATED)`) with `@LastModifiedDate`
3. Optionally add `@CreatedBy` and `@LastModifiedBy` fields for auditor tracking
4. Implement and register an `AuditorAware` bean if using auditor fields
5. Remove `nullable: true` constraints from timestamp fields (no longer needed)
6. Keep `nullable: true` on auditor fields (required for anonymous operations)

====== Automatic Imports for Annotations

To reduce boilerplate when using audit annotations, you can enable automatic imports for common Grails annotations in your `build.gradle`:

[source,groovy]
.build.gradle
----
grails {
    importGrailsCommonAnnotations = true
}
----

When enabled, this automatically imports:

* `jakarta.validation.constraints.*` - Jakarta validation annotations
* `grails.gorm.annotation.*` - All GORM annotations including `@CreatedDate`, `@LastModifiedDate`, `@CreatedBy`, `@LastModifiedBy`
* `grails.plugin.scaffolding.annotation.*` - Scaffolding annotations (if grails-scaffolding is in classpath)

With this setting, you can use the annotations without explicit imports:

[source,groovy]
----
// No import statements needed!
class Book {
    String title

    @CreatedDate      // Automatically imported
    LocalDateTime created

    @LastModifiedDate // Automatically imported
    LocalDateTime modified

    @CreatedBy        // Automatically imported
    String createdBy

    @NotBlank         // jakarta.validation.constraints.NotBlank imported
    @Size(max = 255)  // jakarta.validation.constraints.Size imported
    String author
}
----

====== Custom Star Imports

You can also configure custom star imports for your own packages independently:

[source,groovy]
.build.gradle
----
grails {
    starImports = ['java.util.concurrent', 'groovy.transform', 'com.myapp.annotations']
}
----

This allows you to use classes from these packages without explicit imports throughout your Groovy code. The `starImports` configuration works independently and will be combined with any imports from `importGrailsCommonAnnotations` or `importJavaTime` flags if those are also enabled.

===== 2.5 Scaffolding Namespace View Defaults

Grails 7.1 introduces an opt-in feature for scaffolding that allows namespace-specific scaffolded templates to take priority over non-namespaced view fallbacks.

====== Background

Previously, when a namespace controller requested a view, the scaffolding plugin would only generate a scaffolded view if no view existed at all. This meant that if you had:

* A namespace controller (e.g., `namespace = 'admin'`)
* A non-namespaced view in `grails-app/views/event/index.gsp`
* A namespace-specific scaffolded template in `src/main/templates/scaffolding/admin/index.gsp`

The non-namespaced view would always be used, and the namespace-specific scaffolded template would be ignored.

====== New Behavior

With the new `enableNamespaceViewDefaults` configuration, namespace-specific scaffolded templates can now override non-namespaced view fallbacks. This provides better support for namespace-specific customization of scaffolded views.

====== Configuration

To enable this feature, add the following to your `application.yml`:

[source,yml]
.application.yml
----
grails:
    scaffolding:
        enableNamespaceViewDefaults: true
----

====== View Resolution Priority

When `enableNamespaceViewDefaults` is enabled, the view resolution priority for namespace controllers is:

1. **Namespace-specific view** (e.g., `grails-app/views/admin/event/index.gsp`)
- If exists → used (highest priority)

2. **Namespace-specific scaffolded template** (e.g., `src/main/templates/scaffolding/admin/index.gsp`)
- If exists and no namespace view → used (overrides fallback)

3. **Non-namespaced view fallback** (e.g., `grails-app/views/event/index.gsp`)
- Used if no namespace view or scaffolded template exists

4. **Non-namespaced scaffolded template** (e.g., `src/main/templates/scaffolding/index.gsp`)
- Used if no views exist at all

====== Example Use Case

This feature is useful when you want different scaffolded views for different namespaces:

[source,groovy]
----
// Regular event controller
@Scaffold(RestfulServiceController<Event>)
class EventController {
}

// Admin event controller with namespace
@Scaffold(RestfulServiceController<Event>)
class EventController {
    static namespace = 'admin'
}
----

With `enableNamespaceViewDefaults: true`, you can provide:

* `src/main/templates/scaffolding/index.gsp` - Default scaffolded template
* `src/main/templates/scaffolding/admin/index.gsp` - Admin-specific scaffolded template

The admin controller will use the admin-specific template even if a non-namespaced view exists.

====== Backward Compatibility

This feature is **disabled by default** (`false`), ensuring complete backward compatibility. Existing applications will continue to work without any changes. Enable the feature only when you need namespace-specific scaffolded template support.

===== 2.6 Enhanced Display Constraint with DisplayType Enum

Grails 7.1 enhances the `display` constraint with a new `DisplayType` enum that provides fine-grained control over where properties appear in scaffolded views.

====== New DisplayType Values

The `display` constraint now accepts a `DisplayType` enum value in addition to boolean values:

|===
|Value|Description

|`ALL`|Display in all views. Overrides the default blacklist for properties like `dateCreated` and `lastUpdated`.
|`NONE`|Never display in any view. Equivalent to `display: false`.
|`INPUT_ONLY`|Display only in input views (create and edit forms).
|`OUTPUT_ONLY`|Display only in output views (show and index/list views).
|===

====== Example Usage

[source,groovy]
----
import static grails.gorm.validation.DisplayType.*

class Book {
    String title
    String isbn
    Date dateCreated
    Date lastUpdated
    String internalNotes

    static constraints = {
        dateCreated display: ALL         // Override blacklist, show in all views
        lastUpdated display: OUTPUT_ONLY // Show only in show/index views
        isbn display: INPUT_ONLY         // Show only in create/edit forms
        internalNotes display: NONE      // Never show
    }
}
----

====== Backward Compatibility

Boolean values continue to work as before:

* `display: true` - Default behavior (property is displayed)
* `display: false` - Equivalent to `DisplayType.NONE`

No changes are required for existing applications using boolean values.

===== 2.7 @Scaffold Annotation (Preferred Approach)

Starting in Grails 7.1, the `@Scaffold` annotation is the preferred approach for enabling scaffolding on controllers and services. While the legacy `static scaffold = Domain` syntax is still supported, the annotation provides additional features and flexibility.

====== Benefits of @Scaffold

* **Supports both controllers and services** - The annotation works on both artefact types
* **Custom class extension** - Specify a custom class to extend using the generic syntax
* **Service-backed controllers** - Create controllers that delegate to a service layer for better separation of concerns
* **Read-only mode** - Built-in support for read-only scaffolding

====== Migration Examples

**Basic controller scaffolding:**

[source,groovy]
----
// Legacy syntax
class BookController {
    static scaffold = Book
}

// New preferred syntax
import grails.plugin.scaffolding.annotation.Scaffold

@Scaffold(Book)
class BookController {
}
----

**Scaffolded service:**

[source,groovy]
----
import grails.plugin.scaffolding.annotation.Scaffold

@Scaffold(Book)
class BookService {
}
----

**Service-backed controller (delegates to BookService):**

[source,groovy]
----
import grails.plugin.scaffolding.annotation.Scaffold
import grails.plugin.scaffolding.RestfulServiceController

@Scaffold(RestfulServiceController<Book>)
class BookController {
}
----

**Custom class to extend:**

[source,groovy]
----
import grails.plugin.scaffolding.annotation.Scaffold
import com.example.MyCustomService

@Scaffold(MyCustomService<Book>)
class BookService {
}
----

**Read-only scaffolding:**

[source,groovy]
----
import grails.plugin.scaffolding.annotation.Scaffold

@Scaffold(domain = Book, readOnly = true)
class BookController {
}
----

====== CLI Commands

New CLI commands are available to generate scaffolded controllers and services:

[source,bash]
----
# Generate a scaffolded controller
grails create-scaffold-controller Book

# Generate a scaffolded service
grails create-scaffold-service Book

# Generate both service and controller
grails generate-scaffold-all Book
----

These commands support options like `--extends` to specify a custom class to extend, `--namespace` for controller namespacing, and `--service` to use `RestfulServiceController`.

For full details, see the link:{guidePath}scaffolding.html[Scaffolding] documentation.

===== 2.8 URL Mapping Group Defaults

The `group` method in URL mappings now accepts default parameters that are inherited by all child mappings:

[source,groovy]
----
group "/api", namespace: 'api', controller: 'resource', {
    "/list"(action: 'list')    // inherits namespace and controller
    "/show"(action: 'show')    // inherits namespace and controller
}
----

Nested groups merge defaults — inner groups inherit and can extend or override outer group defaults. Child mappings can override any default explicitly. This is a new additive feature and does not affect existing URL mappings.

For full details, see the link:{guidePath}theWebLayer/urlmappings/mappingToControllersAndActions.html#_group_defaults[Group Defaults] documentation.

===== 2.9 URL Mapping Wildcard Validation

Grails now validates wildcard-captured URL mapping variables (`$controller`, `$action`, `$namespace`) against registered controller artefacts at request time. When a captured value does not match a registered artefact, the mapping is skipped and the next mapping is tried.

This is a new behavior that is **enabled by default**. It allows patterns like:

[source,groovy]
----
group "/topics", {
    "/$action"(controller: 'topic')    // tried first — only matches real actions
    "/$id"(controller: 'topic', action: 'show')  // fallback for non-action values
}
----

Hardcoded controller/action values in mappings are not affected — only wildcard-captured values are validated.

If this causes issues with existing URL mappings, you can disable it in `application.yml`:

[source,yaml]
----
grails:
    web:
        url:
            mapping:
                validateWildcards: false
----