silverstripe-framework/docs/en/02_Developer_Guides/00_Model/10_Versioning.md

title: Versioning summary: Add versioning to your database content through the Versioned extension.

Versioning

Database content in SilverStripe can be "staged" before its publication, as well as track all changes through the lifetime of a database record.

It is most commonly applied to pages in the CMS (the SiteTree class). Draft content edited in the CMS can be different from published content shown to your website visitors.

Versioning in SilverStripe is handled through the Versioned class. As a DataExtension it is possible to be applied to any DataObject subclass. The extension class will automatically update read and write operations done via the ORM via the augmentSQL database hook.

Adding Versioned to your DataObject subclass works the same as any other extension. It has one of two behaviours, which can be applied via the constructor argument.

By default, adding the `Versioned extension will create a "Stage" and "Live" stage on your model, and will also track versioned history.

use SilverStripe\Versioned\Versioned;
use SilverStripe\ORM\DataObject;

class MyStagedModel extends DataObject 
{
    private static $extensions = [
        Versioned::class
    ];
}

Alternatively, staging can be disabled, so that only versioned changes are tracked for your model. This can be specified by setting the constructor argument to "Versioned"

use SilverStripe\ORM\DataObject;

class VersionedModel extends DataObject 
{
    private static $extensions = [
        "SilverStripe\\ORM\\Versioning\\Versioned('Versioned')"
    ];
}

The extension is automatically applied to `SiteTree` class. For more information on extensions see [Extending](../extending) and the [Configuration](../configuration) documentation.

Versioning only works if you are adding the extension to the base class. That is, the first subclass of `DataObject`. Adding this extension to children of the base class will have unpredictable behaviour.

Versioned gridfield extension

By default the versioned module includes a VersionedGridfieldDetailForm that can extend gridfield with versioning support for models.

You can enable this on a per-model basis using the following code:

use SilverStripe\ORM\DataObject;
use SilverStripe\Versioned\Versioned;
class MyBanner extends DataObject {
    private static $extensions = [
        Versioned::class,
    ];
    private static $versioned_gridfield_extensions = true;
}

This can be manually enabled for a single gridfield, alternatively, by setting the following option on the GridFieldDetailForm component.

use SilverStripe\CMS\Model\SiteTree;
use SilverStripe\Forms\GridField\GridField;
use SilverStripe\Forms\GridField\GridFieldConfig_RelationEditor;
use SilverStripe\Forms\GridField\GridFieldDetailForm;
use SilverStripe\Versioned\VersionedGridFieldItemRequest;
class Page extends SiteTree
{
    public function getCMSFields()
    {
        $fields = parent::getCMSFields();
        $config = GridFieldConfig_RelationEditor::create();
        $config
            ->getComponentByType(GridFieldDetailForm::class)
            ->setItemRequestClass(VersionedGridFieldItemRequest::class);
        $gridField = GridField::create('Items', 'Items', $this->Items(), $config);
        $fields->addFieldToTab('Root.Items', $gridField);
        return $fields;
    }
}

Database Structure

Depending on whether staging is enabled, one or more new tables will be created for your records. <class>_versions is always created to track historic versions for your model. If staging is enabled this will also create a new <class>_Live table once you've rebuilt the database.

Note that the "Stage" naming has a special meaning here, it will leave the original table name unchanged, rather than adding a suffix.

• MyRecord table: Contains staged data
• MyRecord_Live table: Contains live data
• MyRecord_Versions table: Contains a version history (new record created on each save)

Similarly, any subclass you create on top of a versioned base will trigger the creation of additional tables, which are automatically joined as required:

• MyRecordSubclass table: Contains only staged data for subclass columns
• MyRecordSubclass_Live table: Contains only live data for subclass columns
• MyRecordSubclass_Versions table: Contains only version history for subclass columns

While not explicit DataObjects, many_many relationships create their own sets of records on their own tables. These records represent content changes to a DataObject, and are therefore versioned. If you have, for instance, a versioned Product DataObject with many_many categories, the following tables will be created:

• Product
• Product_Live
• Product_versions
• Product_Categories
• Product_Categories_Live
• Product_Categories_versions

Usage

Reading Versions

By default, all records are retrieved from the "Draft" stage (so the MyRecord table in our example). You can explicitly request a certain stage through various getters on the Versioned class.

// Fetching multiple records
$stageRecords = Versioned::get_by_stage('MyRecord', Versioned::DRAFT);
$liveRecords = Versioned::get_by_stage('MyRecord', Versioned::LIVE);

// Fetching a single record
$stageRecord = Versioned::get_by_stage('MyRecord', Versioned::DRAFT)->byID(99);
$liveRecord = Versioned::get_by_stage('MyRecord', Versioned::LIVE)->byID(99);

Historical Versions

The above commands will just retrieve the latest version of its respective stage for you, but not older versions stored in the <class>_versions tables.

$historicalRecord = Versioned::get_version('MyRecord', <record-id>, <version-id>);

The record is retrieved as a `DataObject`, but saving back modifications via `write()` will create a new version, rather than modifying the existing one.

In order to get a list of all versions for a specific record, we need to generate specialized Versioned_Version objects, which expose the same database information as a DataObject, but also include information about when and how a record was published.

$record = MyRecord::get()->byID(99); // stage doesn't matter here
$versions = $record->allVersions();
echo $versions->First()->Version; // instance of Versioned_Version

Writing Versions and Changing Stages

The usual call to DataObject->write() will write to the draft stage. If the current stage is set to Versioned::LIVE (as defined by Versioned::current_stage()) then the record will also be updated on the live stage. Through this mechanism the draft stage is the latest source of truth for any record.

In addition, each call will automatically create a new version in the <class>_versions table. To avoid this, use Versioned::writeWithoutVersion() instead.

To move a saved version from one stage to another, call writeToStage() on the object. The process of moving a version to a different stage is also called "publishing". This can be done via one of several ways:

• copyVersionToStage which will allow you to specify a source (which could be either a version number, or a stage), as well as a destination stage.
• publishSingle Publishes this record to live from the draft.
• publishRecursive Publishes this record, and any dependant objects this record may refer to. See "DataObject ownership" for reference on dependant objects.

$record = Versioned::get_by_stage('MyRecord', Versioned::DRAFT)->byID(99);
$record->MyField = 'changed';
// will update `MyRecord` table (assuming Versioned::current_stage() == 'Stage'),
// and write a row to `MyRecord_versions`.
$record->write(); 
// will copy the saved record information to the `MyRecord_Live` table
$record->publishRecursive();

Similarly, an "unpublish" operation does the reverse, and removes a record from a specific stage.

$record = MyRecord::get()->byID(99); // stage doesn't matter here
// will remove the row from the `MyRecord_Live` table
$record->deleteFromStage(Versioned::LIVE);

Forcing the Current Stage

The current stage is stored as global state on the object. It is usually modified by controllers, e.g. when a preview is initialized. But it can also be set and reset temporarily to force a specific operation to run on a certain stage.

$origMode = Versioned::get_reading_mode(); // save current mode
$obj = MyRecord::getComplexObjectRetrieval(); // returns 'Live' records
Versioned::set_reading_mode(Versioned::DRAFT); // temporarily overwrite mode
$obj = MyRecord::getComplexObjectRetrieval(); // returns 'Stage' records
Versioned::set_reading_mode($origMode); // reset current mode

DataObject ownership

Typically when publishing versioned DataObjects, it is necessary to ensure that some linked components are published along with it. Unless this is done, site front-end content can appear incorrectly published.

For instance, a page which has a list of rotating banners will require that those banners are published whenever that page is.

The solution to this problem is the ownership API, which declares a two-way relationship between objects along database relations. This relationship is similar to many_many/belongs_many_many and has_one/has_many, however it relies on a pre-existing relationship to function.

For instance, in order to specify this dependency, you must apply owns on the owner to point to any owned relationships.

When pages of type MyPage are published, any owned images and banners will be automatically published, without requiring any custom code.

use SilverStripe\Versioned\Versioned;
use SilverStripe\Assets\Image;
use Page;

class MyPage extends Page 
{
    private static $has_many = [
        'Banners' => Banner::class
    ];
    private static $owns = [
        'Banners'
    ];
}
class Banner extends Page 
{
    private static $extensions = [
        Versioned::class
    ];
    private static $has_one = [
        'Parent' => MyPage::class,
        'Image' => Image::class,
    ];
    private static $owns = [
        'Image'
    ];
}

Note that ownership cannot be used with polymorphic relations. E.g. has_one to non-type specific DataObject.

DataObject ownership with custom relations

In some cases you might need to apply ownership where there is no underlying db relation, such as those calculated at runtime based on business logic. In cases where you are not backing ownership with standard relations (has_one, has_many, etc) it is necessary to declare ownership on both sides of the relation.

This can be done by creating methods on both sides of your relation (e.g. parent and child class) that can be used to traverse between each, and then by ensuring you configure both owns config (on the parent) and owned_by (on the child).

E.g.

use SilverStripe\Versioned\Versioned;
use SilverStripe\ORM\DataObject;

class MyParent extends DataObject 
{
    private static $extensions = [
        Versioned::class
    ];
    private static $owns = [
        'ChildObjects'
    ];
    public function ChildObjects() 
    {
        return MyChild::get();
    }
}
class MyChild extends DataObject 
{
    private static $extensions = [
        Versioned::class
    ];
    private static $owned_by = [
        'Parent'
    ];
    public function Parent() 
    {
        return MyParent::get()->first();
    }
}

DataObject Ownership in HTML Content

If you are using [DBHTMLText](api:SilverStripe\ORM\FieldType\DBHTMLText) or [DBHTMLVarchar](api:SilverStripe\ORM\FieldType\DBHTMLVarchar) fields in your DataObject::$db definitions, it's likely that your authors can insert images into those fields via the CMS interface. These images are usually considered to be owned by the DataObject, and should be published alongside it. The ownership relationship is tracked through an [image] shortcode, which is automatically transformed into an <img> tag at render time. In addition to storing the image path, the shortcode references the database identifier of the Image object.

Changesets, a.k.a "Campaigns"

Changes to many DataObjects can grouped together using the ChangeSet object, better known by its frontend name, "Campaign" (provided the campaign-admin module is installed). By grouping a series of content changes together as one cohesive unit, content editors can bulk publish or revert an entire body of content all at once, which affords them much more power and control over interdependent content types.

Records can be added to a changeset in the CMS by using the "Add to campaign" button that is available on the edit forms of all pages and files. Programmatically, this is done by creating a SilverStripe\Versioned\ChangeSet object and invoking its addObject(DataObject $record) method.

Any DataObject can exist in any number of changesets, and even added to a changeset in advance of being published. While a record need not have modifications to be part of a changeset, for practical purposes, changesets are only concerned with records that have modifications.

By including an object in a changeset, the user is implicitly including all of that object's owned records (as declared by the $owns setting). This ensures that when a changeset is published (or reverted), the action cascades through not only all of the items explicitly added to the changeset, but also all of the records that each of those items owns.

ChangeSet actions

Actions available on the frontend, i.e. those which are intended to be triggered by an end user, include:

• $myChangeSet->addObject(DataObject $record): Add a record and all of its owned records to the changeset (canEdit() dependent)
• $myChangeSet->removeObject(DataObject $record): Removes a record and all of its owned records from the changeset (canEdit() dependent)
• $myChangeSet->::publish(): Publishes all items in the changeset that have modifications, along with all their owned records (canPublish() dependent). Closes the changeset on completion.
• $myChangeSet->::revert(): Reverts all items in the changeset that have modifications, along with all their owned records (canRevert() dependent). Closes the changeset on completion.

Changesets cannot be "unpublished." Instead, a new changeset should be created to reverse the actions of the prior one.

Actions available on the backend, i.e. those which should only be invoked programmatically include:

• $myChangeSet->sync(): Find all owned records with modifications for each item in the changeset, and include them implicitly.
• $myChangeSet->validate(): Ensure all owned records with modifications for each item in the changeset are included. This method should not need to be invoked if sync() is being used on each mutation to the changeset.

ChangeSet states

Changesets can exists in five different states:

• open No action has been taked on the changeset. Resolves to publishing or reverting.
• publishing: The changeset is in the process of publishing its items. Resolves to to published.
• reverting: The changeset is in the process of reverting changes to its items. Resolves to reverted.
• published: The changeset has published changes to all of its items and its now closed.
• reverted: The changeset has reverted changes to all of its items and its now closed.

Custom SQL

We generally discourage writing Versioned queries from scratch, due to the complexities involved through joining multiple tables across an inherited table scheme (see Versioned::augmentSQL()). If possible, try to stick to smaller modifications of the generated DataList objects.

Example: Get the first 10 live records, filtered by creation date:

$records = Versioned::get_by_stage('MyRecord', Versioned::LIVE)->limit(10)->sort('Created', 'ASC');

Permissions

By default, Versioned will come out of the box with security extensions which restrict the visibility of objects in Draft (stage) or Archive viewing mode.

As is standard practice, user code should always invoke `canView()` on any object before rendering it. DataLists do not filter on `canView()` automatically, so this must be done via user code. This be be achieved either by wrapping `<% if $canView %>` in your template, or by implementing your visibility check in PHP.

Versioned object visibility can be customised in one of the following ways by editing your user code:

• Override the canViewVersioned method in your code. Make sure that this returns true or false if the user is not allowed to view this object in the current viewing mode.
• Override the canView method to override the method visibility completely.

E.g.

use SilverStripe\Versioned\Versioned;
use SilverStripe\Security\Permission;
use SilverStripe\ORM\DataObject;

class MyObject extends DataObject 
{
    private static $extensions = [
        Versioned::class,
    ];
    
    public function canViewVersioned($member = null) 
    {
        // Check if site is live
        $mode = $this->getSourceQueryParam("Versioned.mode");
        $stage = $this->getSourceQueryParam("Versioned.stage");
        if ($mode === 'Stage' && $stage === 'Live') {
            return true;
        }
        
        // Only admins can view non-live objects
        return Permission::checkMember($member, 'ADMIN');
    }
}

If you want to control permissions of an object in an extension, you can also use one of the below extension points in your DataExtension subclass:

• canView to update the visibility of the object's canView
• canViewNonLive to update the visibility of this object only in non-live mode.

Note that unlike canViewVersioned, the canViewNonLive method will only be invoked if the object is in a non-published state.

E.g.

use SilverStripe\Security\Permission;
use SilverStripe\ORM\DataExtension;

class MyObjectExtension extends DataExtension 
{
    public function canViewNonLive($member = null) 
    {
        return Permission::check($member, 'DRAFT_STATUS');
    }
}

If none of the above checks are overridden, visibility will be determined by the permissions in the TargetObject.non_live_permissions config.

E.g.

use SilverStripe\Versioned\Versioned;
use SilverStripe\ORM\DataObject;

class MyObject extends DataObject 
{
    private static $extensions = [
        Versioned::class,
    ];
    private static $non_live_permissions = ['ADMIN'];
}

Versioned applies no additional permissions to canEdit or canCreate, and such these permissions should be implemented as per standard unversioned DataObjects.

Page Specific Operations

Since the Versioned extension is primarily used for page objects, the underlying SiteTree class has some additional helpers.

Templates Variables

In templates, you don't need to worry about this distinction. The $Content variable contain the published content by default, and only preview draft content if explicitly requested (e.g. by the "preview" feature in the CMS, or by adding ?stage=Stage to the URL). If you want to force a specific stage, we recommend the Controller->init() method for this purpose, for example:

mysite/code/MyController.php

public function init() 
{
    parent::init();
    Versioned::set_stage(Versioned::DRAFT);
}

Controllers

The current stage for each request is determined by VersionedRequestFilter before any controllers initialize, through Versioned::choose_site_stage(). It checks for a Stage GET parameter, so you can force a draft stage by appending ?stage=Stage to your request. The setting is "sticky" in the PHP session, so any subsequent requests will also be in draft stage.

The `choose_site_stage()` call only deals with setting the default stage, and doesn't check if the user is authenticated to view it. As with any other controller logic, please use `DataObject->canView()` to determine permissions, and avoid exposing unpublished content to your users.

API Documentation

• Versioned