Versioning#

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

Versioning in Silverstripe CMS is handled through the Versioned extension class. As an Extension it is possible to be applied to any DataObject subclass. The extension class will automatically update read and write operations performed via the ORM because it implements the augmentSQL extension hooks defined in DataQuery::getFinalisedQuery().

The Versioned extension is applied to pages in the CMS (the SiteTree class) - along with some other core DataObject models such as files - by default. Draft content edited in the CMS can be different from published content shown to your website visitors.

Understanding versioning concepts#

This section discusses how Silverstripe CMS implements versioning and related high level concepts without digging into technical details. For the technical part, skip to Implementing a versioned DataObject below.

Stages#

In most cases, you'll want to have one polished version of a Page visible to the general public while your editors might be making additional changes on a draft version. Silverstripe CMS handles this through the concept of stages.

By default, adding the Versioned extension to a DataObject will create 2 stages:

• "Stage" for tracking draft content (aka "draft")
• "Live" for tracking content publicly visible (aka "published").

Publishing a versioned DataObject is equivalent to copying the version from the "Stage" stage to the "Live" stage.

If you just want to keep track of the version history of a model's records but you don't need to separate draft and published versions, you can apply the Versioned extension to your DataObject without stages. This will allow you to keep track of all changes that have been applied to a DataObject and who made them.

Ownership and relations between DataObject models#

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

For instance, a page which has a list of rotating banners will require them to be published whenever that page is.

This is solved through the Ownership API, which declares that one model "owns" the models in a given existing relationship for the purposes of versioning and staging. It relies on a pre-existing relationship to function.

Cascade publishing#

If an object "owns" other objects, you'll usually want to publish the child objects when the parent object gets published. If those child objects themselves own other objects, you'll want the grand-children to be published along with the parent.

Silverstripe CMS makes this possible by using the concept of cascade publishing. You can choose to recursively publish an object. When an object is recursively published – either through a user action or through code – all other records it owns that implement the Versioned extension will automatically be published. Publication will also cascade to children of children and so on.

A non-recursive publish operation is also available if you want to publish a new version of a object without cascade publishing all its children.

Ownership of unversioned object#

An unversioned object can own a versioned object.

An unversioned object can be configured to automatically publish owned versioned objects on save.

An unversioned object can also be owned by a versioned object. This can be used to recursively publish children-of-children objects without requiring the intermediate relationship to go through a versioned object. This behavior can be helpful if you wish to group multiple versioned objects together.

Ownership through media insertion in content#

Images and other files are tracked as versioned objects. If a file is referenced through an HTML text field, it needs to be published for it to be accessible to the public. Silverstripe CMS will automatically pick up when an object references files through an HTML text field and recursively publish those files.

This behavior works both for versioned and unversioned objects.

Grouping versioned DataObject records into a ChangeSet#

Sometimes, multiple pages or records may be related in organic ways that cannot be properly expressed through an ownership relation. There's still value in being able to publish those as a block.

For example, your editors may be about to launch a new contest through their website. They've drafted a page to promote the contest, another page with the rules and conditions, a registration page for users to sign up, some promotional images, new sponsor records, etc. All this content needs to become visible simultaneously.

Changes to many objects can be grouped together using the ChangeSet object. By grouping a series of content changes together as a cohesive unit. This can allow bulk publish an entire body of content all at once, which affords them much more power and control over interdependent content types. Note that there is currently no UI to enable this functionality, so it must be done programmatically.

Programmatically, this is done by creating a ChangeSet object and invoking its addObject(DataObject $record) method.

Implicit vs. Explicit inclusions#

Items can be added to a changeset in two ways -- implicitly and explicitly.

An implicit inclusion occurs when a record is added to a changeset by virtue of another object declaring ownership of it via the $owns setting. Implicit inclusion of owned objects ensures that when a changeset is published, 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.

An explicit inclusion is much more direct, occurring only when a user has opted to include a record in a changeset either through the UI or programmatically.

It is possible for an item to be included both implicitly and explicitly in a changeset. For instance, if a page owns a file, and the page gets added to a changeset, the file is implicitly added. That same file, however, can still be added to the changeset explicitly through the file editor. In this case, the file is considered to be explicitly added. If the file is later removed from the changeset, it is then considered implicitly added, due to its owner page still being in the changeset.

Implementing a versioned DataObject#

This section explains how to take a regular DataObject and add versioning to it.

Applying the Versioned extension to your DataObject#

Adding versioning to a DataObject model is as easy as applying the Versioned extension to it, either via PHP or YAML configuration. This will apply versioning with stages, meaning you can have a draft and a published version of your records.

namespace App\Model;

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

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

App\Model\MyStagedModel:
  extensions:
    - SilverStripe\Versioned\Versioned

Alternatively, staging can be disabled, so that only versioned changes are tracked for your model. This can be specified by using the .versioned service variant that provides only version history, and no staging.

namespace App\Model;

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

class VersionedModel extends DataObject
{
    private static $extensions = [
        Versioned::class . '.versioned',
    ];
}

App\Model\MyStagedModel:
  extensions:
    - SilverStripe\Versioned\Versioned.versioned

Versioning a many_many relation#

If you want to track versions of many_many relationships, you can do so using the "through" setting on a many_many definition. This setting allows you to specify a custom DataObject through which to map the many_many relation. As such, it is possible to version your many_many data by versioning a "through" DataObject. For example:

namespace App\Model;

use SilverStripe\ORM\DataObject;

class Product extends DataObject
{
    private static $db = [
        'Title' => 'Varchar(100)',
        'Price' => 'Currency',
    ];

    private static $many_many = [
        'Categories' => [
            'through' => 'ProductCategory',
            'from' => 'Product',
            'to' => 'Category',
        ],
    ];
}

namespace App\Model;

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

class ProductCategory extends DataObject
{
    private static $db = [
        'SortOrder' => 'Int',
    ];

    private static $has_one = [
        'Product' => Product::class,
        'Category' => Category::class,
    ];

    private static $extensions = [
        Versioned::class,
    ];
}

Controlling permissions to versioned DataObject models#

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.

Version specific can methods#

Versioned DataObjects get additional permission check methods to verify what operation a Member is allowed to perform:

• canPublish(): Determines if a given Member is allowed to publish the record
• canUnpublish() Determines if a given Member is allowed to unpublish the record
• canViewStage() Determines if a given Member can view the latest version of this record on a specific stage. Beware that this is not invoked when calling canView(). If you want to affect the result of regular canView() checks, implement canViewVersioned() instead.
• canViewVersioned() Provides additional can view checks for versioned records. This is called by canView() and should not be called directly.

The existing canDelete() method is used to check if a given Member is allowed to archive the record. The Versioned extension enhances this permission check for published content to ensure members that cannot unpublish content also cannot archive it.

These methods accept an optional Member argument. If not provided, they will assume you want to check the permission against the current Member. When performing a version operation on behalf of a Member, you'll probably want to use these methods to confirm they are authorised.

$record = MyRecord::get()->byID(99);
if ($record->canPublish()) {
    $record->publishRecursive();
}

The canViewStage() method can be used to check if a Member can view a specific stage of a record. It should be invoked by user code to check if a record is visible in the given stage.

use SilverStripe\Versioned\Versioned;

// Check if `$member` can view the Live version of $record.
$record->canViewStage(Versioned::LIVE, $member);

// Check if `$member` can view the "Stage" version of $record.
$record->canViewStage(Versioned::DRAFT, $member);

// Both parameters are optional. This is equivalent to calling the method with Versioned::LIVE and
// Security::getCurrentUser();
$record->canViewStage();

For the can methods that all DataObject models have, see Model-Level Permissions.

Customising permissions for a versioned DataObject#

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

• Override the canViewVersioned() method in your DataObject subclass. 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, regardless of what stage is being viewed.

E.g.

namespace App\Model;

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

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 === Versioned::LIVE) {
            return true;
        }

        // Only admins can view non-live records
        return Permission::checkMember($member, 'ADMIN');
    }
}

If you want to control permissions of an object in an extension, you can also implement one of the below extension hook methods in your Extension subclass:

• canView() to update the record's canView permissions
• canViewNonLive() to update the visibility of this object only in non-live mode specifically.

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

E.g.

namespace App\Extension;

use SilverStripe\Core\Extension;
use SilverStripe\Security\Permission;

class MyObjectExtension extends Extension
{
    protected function canViewNonLive($member = null)
    {
        if (!Permission::check($member, 'DRAFT_STATUS')) {
            return false;
        }

        // Defer to the result of the main canViewVersioned() permission checks
        return null;
    }
}

If none of the above checks are overridden, visibility will be determined by the permissions in the non_live_permissions configuration on the target model class.

E.g.

namespace App\Model;

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

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.

Defining ownership between related versioned DataObject models#

You can use the owns configuration property on a DataObject to specify which relationships are ownership relationships. The owns property should be defined on the owner DataObject.

For example, let's say you have a MyPage page type that displays banners containing an image. Each MyPage owns many Banners, which in turn owns an Image.

namespace App\PageType;

use App\Model\Banner;
use Page;

class MyPage extends Page
{
    private static $has_many = [
        'Banners' => Banner::class,
    ];

    private static $owns = [
        'Banners',
    ];
}

namespace App\Model;

use App\PageType\MyPage;
use SilverStripe\Assets\Image;
use SilverStripe\ORM\DataObject;
use SilverStripe\Versioned\Versioned;

class Banner extends DataObject
{
    private static $extensions = [
        Versioned::class,
    ];

    private static $has_one = [
        'Parent' => MyPage::class,
        'Image' => Image::class,
    ];

    private static $owns = [
        'Image',
    ];
}

If a MyPage record gets published, all its related Banners will also be published, which will cause all related Image records to be published.

Note that this relationship is for publishing specifically, and is not affected by unpublishing or archiving the owner record. To ensure unpublish and archive actions affect owned records, cascade_deletes must be used. See Cascading deletions for more information about this interaction.

namespace App\PageType;

class MyPage extends Page
{
    private static $has_many = [
        'Banners' => Banner::class,
    ];

    private static $cascade_deletes = [
        'Banners',
    ];
}

You must declare both owns and cascade_deletes if you want all publish, unpublish, and archive actions to carry through.

Unversioned DataObject ownership#

Ownership can be used with non-versioned DataObjects, as the necessary functionality is included by default by the versioned object through the RecursivePublishable extension which is applied to all objects.

However, it is important to note that even when saving un-versioned objects, it is necessary to explicitly call publishRecursive() to trigger a recursive publish.

The owns feature works the same regardless of whether these objects are versioned, so you can use any combination of versioned or unversioned dataobjects. You only need to call publishRecursive() on the specific record for which you are saving changes.

DataObject ownership with custom relations#

In some cases you might need to apply ownership where there is no underlying database 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).

For example:

namespace App\Model;

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

class MyParent extends DataObject
{
    private static $extensions = [
        Versioned::class,
    ];

    private static $owns = [
        'ChildObjects',
    ];

    public function ChildObjects()
    {
        return MyChild::get();
    }
}

namespace App\Model;

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

class MyChild extends DataObject
{
    private static $extensions = [
        Versioned::class,
    ];

    private static $owned_by = [
        'Parent',
    ];

    public function Parent()
    {
        return MyParent::get()->first();
    }
}

Image ownership in HTML content via the WYSIWYG editor#

If you are using DBHTMLText or 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 and ensures it's published appropriately.

Controlling how CMS users interact with versioned DataObject records#

The versioned module includes a VersionedGridfieldDetailForm extension which provides versioning support for DataObjects edited in a GridField. This is applied to GridFieldDetailForm by default.

You can disable this on a per-model basis by setting the versioned_gridfield_extensions configuration property to false. You can do that in PHP:

namespace App\Model;

use SilverStripe\ORM\DataObject;

class MyBanner extends DataObject
{
    private static $versioned_gridfield_extensions = false;
    // ...
}

Or via YAML configuration:

App\Model\MyBanner:
  versioned_gridfield_extensions: false

This can also be manually enabled for a single GridField by passing the VersionedGridFieldItemRequest class name to the setItemRequestClass() method on a GridFieldConfig instance.

namespace {

    use SilverStripe\CMS\Model\SiteTree;
    use SilverStripe\Forms\FieldList;
    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()
        {
            $this->beforeUpdateCMSFields(function (FieldList $fields) {
                $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 parent::getCMSFields();
        }
    }
}

Interacting with versioned DataObject records#

This section deals with specialised operations that can be performed on versioned DataObjects.

Reading versions by stage#

By default, all records are retrieved from the "Stage" (aka draft) stage, which pulls from the same database table you would be using if there were no stages or versions at all.

You can explicitly request a specific stage through various static methods on the Versioned class.

use SilverStripe\Versioned\Versioned;

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

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

You can also use Versioned::withVersionedMode() in conjunction with Versioned::set_stage() to temporarily change what stage is being used for queries.

use SilverStripe\Versioned\Versioned;

$liveRecords = Versioned::withVersionedMode(function () {
    // Set the reading mode we want - note we don't have to set it back afterwards,
    // that will be done for us automatically.
    Versioned::set_stage(Versioned::LIVE);
    // Return the result so we can assign it to the `$liveRecords` variable.
    return MyRecord::get();
});

You can use Versioned::set_stage() outside of calls to Versioned::withVersionedMode(), but you must remember to set the reading mode back to what is was before you started, or you risk unexpected side effects. The only exception to this is if you explicitly want the rest of the request execution to be performed with a given reading mode (e.g. if a given action on a controller must be explicitly completely executed ina given stage).

use SilverStripe\Versioned\Versioned;

// Temporarily store the current mode before setting the mode we want to use
$oldMode = Versioned::get_reading_mode();
Versioned::set_stage(Versioned::LIVE);

$liveRecords = MyRecord::get();

// Don't forget to set the mode back afterwards!
Versioned::set_reading_mode($oldMode);

Reading historical versions#

The above commands will just retrieve the latest version of its respective stage for you, but not older versions stored in the <originalTable>_versions tables (see How versioned DataObjects are tracked in the database).

use SilverStripe\Versioned\Versioned;

// the "id" parameter is the ID of the record, and the "version" parameter is the specific version number to fetch
$historicalRecord = Versioned::get_version(MyRecord::class, id: 5, version: 6);

The record is retrieved as a regular DataObject record with its values set to the values it had when that version was originally saved.

In order to get a list of all versions for a specific record, we get the record version data as 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.

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

Writing changes to a versioned DataObject#

When you call the write() method on a versioned DataObject record, this will transparently create a new version of the record in the "Stage" stage.

To write your changes without creating new version, call writeWithoutVersion() instead.

// This will retrieve the latest draft version of record ID 99.
$record = MyRecord::get()->byID(99);
// This will output the version ID. Let's assume it's 13.
echo $record->Version;


$record->Title = "Foo Bar";
// This will create a new version of record ID 99.
$record->write();
// Will output 14 (because a new version was created).
echo $record->Version;

$record->Title = "FOO BAR";
// This will edit the latest version of record ID 99.
$record->writeWithoutVersion();
// Will still output 14 (because we edited the existing version).
echo $record->Version;

An "unpublish" operation removes that record from the "Live" stage.

Publishing a versioned DataObject#

There's two main methods used to publish a versioned DataObject record:

• publishSingle() publishes only this record to live from the draft
• publishRecursive() publishes this record and any dependent objects this record may refer to.

In most regular cases, you'll want to use publishRecursive().

publishRecursive() can be called on unversioned DataObject as well, since the RecursivePublishable extension is applied to DataObject by default.

$record = MyRecord::get()->byID(99);
$record->MyField = 'changed';

// Will create a new revision in "Stage". Editors will be able to see this revision,
// but unauthenticated visitors to the website will not see it.
$record->write();

// This will publish the changes so they are visible publicly.
$record->publishRecursive();

Unpublishing and archiving a versioned DataObject#

Archiving and unpublishing are similar operations, both will prevent a versioned DataObject from being publicly accessible. Archiving will also remove the record from the "Stage" stage; other ORMs may refer to this concept as soft-deletion.

Both of these operations create a new entry in the relevant _Versions table with the WasDeleted column set to 1 (see How versioned DataObjects are tracked in the database).

Call doUnpublish() to unpublish an item. Either call doArchive() or simply call delete() to archive an item. The Silverstripe ORM doesn't allow you to hard-delete versioned DataObjects. Instead they are simply removed from all stages, but all version history is retained. This allowed you to restore archived records later on, if you want to.

$record = MyRecord::get()->byID(99);

// Visitors to the site won't be able to see this record anymore, but editors can
// still edit it and re-publish it.
$record->doUnpublish();


// Editors won't be able to see this record anymore, but its version history will
// still be in the database and may be restored.
$record->delete();
// or
$record->doArchive();

Note that doUnpublish() and doArchive() do not work recursively. If you wish to unpublish or archive dependants records, you have to do it manually.

Rolling back to an older version#

Rolling back allows you to return a record to a previous state. You can rollback a single record using the rollbackSingle() method. You can also rollback all dependent records using the rollbackRecursive() method.

Both rollbackSingle() and rollbackRecursive() expect a single argument, which may be a specific version ID or a stage name.

use SilverStripe\Versioned\Versioned;

$record = MyRecord::get()->byID(99);

// This will take the current live version of a record - and all it's associated (owned) records - and copy it to the
// "Stage" stage. This is equivalent to dismissing any draft work and reverting to what was last published.
$record->rollbackRecursive(Versioned::LIVE);

// This will restore a specific version of the record to "Stage" without affecting any owned records.
$versionToRestore = 10;
$record->rollbackSingle($versionToRestore);

// The live version of the record won't be affected unless you publish the record again.
$record->publishRecursive();

Note that internally, rolling back a record creates a new version identical to the restored version. For example, if the live version of $record is #10 and the staged version is #13, rolling back to live will create a version #14 in "Stage" that is identical to version #10.

Restoring an archived version#

Archived records can still be retrieved using get_including_deleted(). This will include archived as well as current records. You can use the isArchived() method to determine if a record is archived or not. Calling the write() method on an archived record will restore it to the "Stage" stage.

use App\Model\MyRecord;
use SilverStripe\Versioned\Versioned;

// This script will restore all archived entries for MyRecord.
$allMyRecords = Versioned::get_including_deleted(MyRecord::class);
foreach ($allMyRecords as $myRecord) {
    if ($myRecord->isArchived()) {
        $myRecord->write();
    }
}

If you already know a specific record was archived and want to restor it, you can also use the rollbackRecursive() and rollbackSingle() methods - but you still have to get a hold of the archived record using get_including_deleted() first.

Interacting with ChangeSet#

This section explains how you can interact with ChangeSets.

Adding and removing DataObject records to a change set#

• $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).

Performing actions on the ChangeSet object#

• $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->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.

Getting information about the state of the ChangeSet#

ChangeSets can exists in three different states:

• open No action has been taken on the ChangeSet. Resolves to publishing or reverting.
• 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. (Future API, not supported yet)

Getting information about items in a ChangeSet#

Each item in the ChangeSet stores VersionBefore and VersionAfter fields. As such, they can compute the type of change they are adding to their parent ChangeSet. Change types include:

• created: This ChangeSet item is for a record that does not yet exist
• modified: This ChangeSet item is for a record that differs from what is on the live stage
• deleted: This ChangeSet item will no longer exist when the ChangeSet is published
• none: This ChangeSet item is exactly as it is on the live stage

Advanced versioning topics#

These topics are targeted towards more advanced use cases that might require developers to extend the behavior of versioning.

How versioned DataObject records are tracked in the database#

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

• MyRecord table: Contains "Stage" (draft) data
• MyRecord_Live table: Contains "Live" (published) data
• MyRecord_Versions table: Contains a version history (new row created on each save, publish, unpublish, archive, and rollback event)

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

• MyRecordSubclass table: Contains only "Stage" (draft) data for subclass columns
• MyRecordSubclass_Live table: Contains only "Live" (published) data for subclass columns
• MyRecordSubclass_Versions table: Contains only version history for subclass columns

Writing custom queries to retrieve versioned DataObject#

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:

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

Controlling what stage is displayed in the front end#

The current stage for each request is determined by VersionedHTTPMiddleware before any controllers initialize, through Versioned::choose_site_stage(). It checks for a stage GET parameter, so you can force a "Stage" (draft) stage by appending ?stage=Stage to your request.

The current stage setting is not "sticky" in the session. Any links presented on the view produced with ?stage=Stage need to have the same GET parameters in order to retain the stage. If you are using the SiteTree->Link() and Controller->Link() methods, this is automatically the case for DataObject links, controller links and form actions. Note that this behaviour applies for unversioned objects as well, since the views these are presented in might still contain dependent objects that are versioned.

You can opt for a session base stage setting through the Versioned.use_session configuration property.

// app/src/Model/MyObject.php
namespace App\Model;

use App\Control\MyObjectController;
use SilverStripe\Control\Controller;
use SilverStripe\Core\Injector\Injector;
use SilverStripe\ORM\DataObject;
use SilverStripe\Versioned\Versioned;

class MyObject extends DataObject
{
    private static $extensions = [
        Versioned::class,
    ];
    // ...

    public function Link()
    {
        return $this->getController()->Link($this->ID);
    }

    public function CustomLink()
    {
        $link = Controller::join_links('custom-route', $this->ID, '?rand=' . rand());
        // Calls VersionedStateExtension->updateLink() which ensures the correct stage is included if necessary
        // updates $link by reference
        $this->extend('updateLink', $link);
        return $link;
    }

    public function LiveLink()
    {
        // Force live link even when current view is in draft mode
        return Controller::join_links($this->getController()->Link($this->ID), '?stage=Live');
    }

    public function getController()
    {
        return Injector::inst()->get(MyObjectController::class);
    }
}

// app/src/Control/MyObjectController.php
namespace App\Control;

use App\Model\MyObject;
use SilverStripe\Control\Controller;
use SilverStripe\Control\HTTPRequest;

class MyObjectController extends Controller
{
    private static $url_segment = 'my-objects';

    public function index(HTTPRequest $request)
    {
        $obj = MyObject::get()->byID($request->param('ID'));
        if (!$obj) {
            return $this->httpError(404);
        }

        // Construct view
        $html = sprintf('<a href="%s">%s</a>', $obj->Link(), $obj->ID);

        return $html;
    }

    public function Link($action = null)
    {
        // Construct link with graceful handling of GET parameters
        $link = Controller::join_links('my-objects', $action);

        // Allow Versioned and other extension to update $link by reference.
        // Calls VersionedStateExtension->updateLink() which ensures the correct stage is included if necessary
        $this->extend('updateLink', $link, $action);

        return $link;
    }
}

# app/_config/routes.yml
SilverStripe\Control\Director:
  rules:
    'my-objects/$ID': 'App\Control\MyObjectController'

Templates variables#

In templates, you don't need to worry about this distinction. The $Content variable contains the published content by default, and previews draft content only 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:

// app/src/Control/MyController.php
namespace App\Control;

use SilverStripe\Control\Controller;

class MyController extends Controller
{
    // ...

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

Low level write and publication methods#

Silverstripe CMS will usually call these low level methods for you. However if you have specialised needs, you may call them directly.

To move a saved version from one stage to another, call writeToStage() on the object, passing in the stage you want to write to. This is used internally to publish DataObjects.

copyVersionToStage() allows you to copy a specific version to a specific stage. This is used internally when performing a rollback, copying whichever version you're rolling back to into the "Stage" stage.

The current stage is stored as global state on the Versioned 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.

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

See Reading versions by stage for more about using reading modes.

Using the history viewer#

You can add the HistoryViewerField to the edit form of any DataObject with the Versioned extension. This will allow CMS users revert to a previous version of the record.

// app/src/Models/MyDataObject.php
namespace App\Models;

use SilverStripe\ORM\DataObject;
use SilverStripe\Versioned\Versioned;
use SilverStripe\VersionedAdmin\Forms\HistoryViewerField;

class MyDataObject extends DataObject
{
    // ...

    private static $extensions = [
        Versioned::class,
    ];

    public function getCMSFields()
    {
        $fields = parent::getCMSFields();
        $fields->addFieldToTab(
            'Root.History',
            HistoryViewerField::create('HistoryViewer')
        );
        return $fields;
    }
}

API documentation#

• Versioned
• HistoryViewerField