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.

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 CMS 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.

Understanding versioning concepts#

This section discusses how Silverstripe CMS implements versioning and related high level concepts without digging into technical details.

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 working off a draft version. Silverstripe CMS handles this through the concept of stage.

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

• "Stage" for tracking draft content
• "Live" for tracking content publicly visible.

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

You can disable stages if your DataObject doesn't require a published version. 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 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.

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 other versioned object. An unversioned object can be configured to automatically publish children 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 object 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 (aka campaigns)#

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. In the CMS, editors can manage ChangeSets through the "Campaign" section, if the silverstripe/campaign-admin module is installed). By grouping a series of content changes together as cohesive unit, content editors can bulk publish 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.

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#

namespace App\Model;

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

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 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',
    ];
}

Defining ownership between related versioned DataObject models#

You can use the owns static private 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 gets published, all its related Banners will also be published, which will cause all Image DataObjects to be published.

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

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 use ->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 top most object in the tree.

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();
    }
}

DataObject ownership in HTML content#

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.

Controlling how CMS users interact with versioned DataObject records#

By default the versioned module includes a VersionedGridfieldDetailForm that extends gridfield with versioning support for DataObjects.

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

namespace App\Model;

use SilverStripe\ORM\DataObject;

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

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

namespace {

    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;
        }
    }
}

Interacting with versioned DataObject records#

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

Reading latest versions by stage#

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.

use SilverStripe\Versioned\Versioned;

// 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);

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 <class>_versions tables.

use SilverStripe\Versioned\Versioned;
$historicalRecord = Versioned::get_version('MyRecord', $recordId, $versionId);

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.

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

Writing changes to a versioned DataObject#

When you call the write() method on a versioned DataObject, this will transparently create a new version of this DataObject 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.
echo $record->Version;

$record->Title = 'FOO BAR';
$record->writeWithoutVersion();
// Will still output 14.
echo $record->Version;

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

Publishing a versioned DataObject#

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

• publishSingle() publishes 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 if they implement the RecursivePublishable extension.

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

// Will create a new revision in Stage. Editors will be able to see this revision, but not visitors to the website.
$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.

Use doUnpublish() to unpublish an item. Simply call delete() to archive an item. The Silverstripe ORM doesn't allow you to hard-delete versioned DataObjects.

$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 it will still be in the database and may be restore.
$record->delete();

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 DataObject to a previous state. You can rollback a single DataObject 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 DataObjects - 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 DataObjects.
$versionToRestore = 10;
$record->rollbackSingle($versionToRestore);

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

Note that internally, rolling back a DataObject creates a new version identical of the restored version ID. 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();
    }
}

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. <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.

• 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

Because many_many relationships create their own sets of records on their own tables, representing content changes to a DataObject, they can therefore be versioned. This is done 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,
    ];
    // ...
}

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', 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 draft stage by appending ?stage=Stage to your request.

Since Silverstripe CMS 4.2, the current stage setting is no longer "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 setting. Warning: This can lead to leaking of unpublished information, if a live URL is viewed in draft mode, and the result is cached due to aggressive cache settings (not varying on cookie values).

// 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 Injector::inst()->get(MyObjectController::class)->Link($this->ID);
    }

    public function CustomLink()
    {
        $link = Controller::join_links('custom-route', $this->ID, '?rand=' . rand());
        // 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(Injector::inst()->get(MyObjectController::class)->Link($this->ID), '?stage=Live');
    }
}

// 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;
    }
}

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

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 DataObject records get additional permission check methods to verify what operation a Member is allowed to perform:

• canPublish()
• canUnpublish()
• canArchive()
• canViewVersioned().

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,

use SilverStripe\Security\Security;

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

There's also a canViewStage() method which can be used to check if a Member can access a specific 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();

Customising permissions for a versioned DataObject#

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.

For example:

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 === '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.

For example:

namespace App\Extension;

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

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.

For example:

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.

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 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(stage) on the object. This is used internally to publish DataObjects.

copyVersionToStage($versionID, $stage) allows you to restore a previous version to a specific stage. This is used internally when performing a rollback.

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);

Using the history viewer#

Since Silverstripe CMS 4.3 you can use the React and GraphQL driven history viewer UI to display historic changes and comparisons for a versioned DataObject. This is automatically enabled for SiteTree objects and content blocks in dnadesign/silverstripe-elemental.

If you want to enable the history viewer for a custom versioned DataObject, you will need to:

• Expose GraphQL scaffolding
• Add the necessary GraphQL queries and mutations to your module
• Register your GraphQL queries and mutations with Injector
• Add a HistoryViewerField to the DataObject's getCMSFields

Setup#

Regardless of which version of silverstripe/graphql your project uses, the setup will be the same - you'll have some DataObject model, somewhere to view that model (e.g. in a ModelAdmin), and some basic JavaScript to tell the history viewer how to handle requests for your model.

For this example we'll start with this simple DataObject:

namespace App\Model;

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

class MyVersionedObject extends DataObject
{
    private static $table_name = 'App_MyVersionedObject';

    private static $db = [
        'Title' => 'Varchar',
    ];

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

Configure frontend asset building#

If you haven't already configured frontend asset (JavaScript/CSS) building for your project, you will need to configure some basic packages to be built in order to enable history viewer functionality. This section includes a very basic webpack configuration which uses @silverstripe/webpack-config.

You can configure your directory structure like so:

// package.json
{
  "name": "my-project",
  "scripts": {
    "build": "yarn && NODE_ENV=production webpack -p --bail --progress",
    "watch": "yarn && NODE_ENV=development webpack --watch --progress"
  },
  "dependencies": {
    "react-apollo": "^2.1.0",
    "graphql-tag": "^2.10.0"
  },
  "devDependencies": {
    "@silverstripe/webpack-config": "^1.7.0",
    "webpack": "^2.6.1"
  },
  "engines": {
    "node": "^10.x"
  }
}

// webpack.config.js
const Path = require('path');
const webpackConfig = require('@silverstripe/webpack-config');

const ENV = process.env.NODE_ENV;
const PATHS = {
  MODULES: 'node_modules',
  ROOT: Path.resolve(),
  SRC: Path.resolve('app/client/src'),
  DIST: Path.resolve('app/client/dist'),
};

module.exports = [
  {
    name: 'js',
    entry: {
      bundle: `${PATHS.SRC}/boot/index.js`,
    },
    output: {
      path: PATHS.DIST,
      filename: 'js/[name].js',
    },
    devtool: (ENV !== 'production') ? 'source-map' : '',
    resolve: webpackConfig.resolveJS(ENV, PATHS),
    externals: webpackConfig.externalJS(ENV, PATHS),
    module: webpackConfig.moduleJS(ENV, PATHS),
    plugins: webpackConfig.pluginJS(ENV, PATHS),
  }
];

// app/client/src/boot/index.js

// We'll populate this file later - for now we just need it to be sure our build setup works.

At this stage, running yarn build should correctly build app/client/dist/js/bundle.js.

Create and use GraphQL schema#

The history viewer uses GraphQL queries and mutations to function. Silverstripe CMS 4 support two major release lines of silverstripe/graphql, so instructions for using each of those are included below.

Define GraphQL schema#

Only a minimal amount of data is required to be exposed via GraphQL scaffolding, and only to the "admin" GraphQL schema. The way you do this varies wildly between silverstripe/graphql v3 and v4.

GraphQL 4#

For more information, see Working with DataObjects - Adding DataObjects to the schema.

# app/_config/graphql.yml
SilverStripe\GraphQL\Schema\Schema:
  schemas:
    admin:
      src:
        - app/_graphql

# app/_graphql/models.yml
App\Model\MyVersionedObject:
  fields: '*'
  operations:
    readOne: true
    rollback: true

Once configured, flush your cache and run dev/graphql/build either in your browser or via sake, and explore the new GraphQL schema to ensure it loads correctly. You can use a GraphQL application such as GraphiQL, or silverstripe/graphql-devtools to view the schema and run queries from your browser:

composer require --dev silverstripe/graphql-devtools dev-master

GraphQL 3#

For more information, see Scaffolding DataObjects into the schema in the GraphQL v3 documentation.

# app/_config/graphql.yml
SilverStripe\GraphQL\Manager:
  schemas:
    admin:
      scaffolding:
        types:
          MyVersionedObject:
            fields: [ID, LastEdited]
            operations:
              readOne: true
              rollback: true
          SilverStripe\Security\Member:
            fields: [ID, FirstName, Surname]
            operations:
              readOne: true

Once configured, flush your cache and explore the new GraphQL schema to ensure it loads correctly. You can use a GraphQL application such as GraphiQL, or silverstripe/graphql-devtools to view the schema and run queries from your browser:

composer require --dev silverstripe/graphql-devtools dev-master

Use the GraphQL query and mutation in JavaScript#

The history viewer interface uses two main operations:

• Read a list of versions for a DataObject
• Revert (aka rollback) to an older version of a DataObject

silverstripe/versioned provides some GraphQL plugins we're taking advantage of here. See Working with DataObjects - Versioned content for more information.

For this we need one query and one mutation:

// app/client/src/state/readOneMyVersionedObjectQuery.js
import { graphql } from 'react-apollo';
import gql from 'graphql-tag';

// Note that "readOneMyVersionedObject" is the query name in the schema, while
// "ReadHistoryViewerMyVersionedObject" is an arbitrary name we're using for this invocation
// of the query
const query = gql`
query ReadHistoryViewerMyVersionedObject ($id: ID!, $limit: Int!, $offset: Int!) {
    readOneMyVersionedObject(
      versioning: {
        mode: ALL_VERSIONS
      },
      filter: {
        id: { eq: $id }
      }
    ) {
      id
      versions (limit: $limit, offset: $offset, sort: {
        version: DESC
      }) {
        pageInfo {
          totalCount
        }
        nodes {
          version
          author {
            firstName
            surname
          }
          publisher {
            firstName
            surname
          }
          deleted
          draft
          published
          liveVersion
          latestDraftVersion
          lastEdited
        }
      }
    }
  }
`;

const config = {
  options({ recordId, limit, page }) {
    return {
      variables: {
        limit,
        offset: ((page || 1) - 1) * limit,
        id: recordId,
        // Never read from the cache. Saved pages should stale the query, and these queries
        // happen outside the scope of apollo's cache. This view is loaded asynchronously anyway,
        // so caching doesn't make any sense until we're full React/GraphQL.
        fetchPolicy: 'network-only',
      }
    };
  },
  props({
    data: {
      error,
      refetch,
      readOneMyVersionedObject,
      loading: networkLoading,
    },
    ownProps: {
      actions = {
        versions: {}
      },
      limit,
      recordId,
    },
  }) {
    const versions = readOneMyVersionedObject || null;

    const errors = error && error.graphQLErrors &&
      error.graphQLErrors.map((graphQLError) => graphQLError.message);

    return {
      loading: networkLoading || !versions,
      versions,
      graphQLErrors: errors,
      actions: {
        ...actions,
        versions: {
          ...versions,
          goToPage(page) {
            refetch({
              offset: ((page || 1) - 1) * limit,
              limit,
              id: recordId,
            });
          }
        },
      },
    };
  },
};

export { query, config };

export default graphql(query, config);

// app/client/src/state/revertToMyVersionedObjectVersionMutation.js
import { graphql } from 'react-apollo';
import gql from 'graphql-tag';

// Note that "rollbackMyVersionedObject" is the mutation name in the schema, while
// "revertToMyVersionedObject" is an arbitrary name we're using for this invocation
// of the mutation
const mutation = gql`
mutation revertToMyVersionedObject($id:ID!, $toVersion:Int!) {
  rollbackMyVersionedObject(
    id: $id
    toVersion: $toVersion
  ) {
    id
  }
}
`;

const config = {
  props: ({ mutate, ownProps: { actions } }) => {
    const revertToVersion = (id, toVersion) => mutate({
      variables: {
        id,
        toVersion,
      },
    });

    return {
      actions: {
        ...actions,
        revertToVersion,
      },
    };
  },
  options: {
    // Refetch versions after mutation is completed
    refetchQueries: ['ReadHistoryViewerMyVersionedObject']
  }
};

export { mutation, config };

export default graphql(mutation, config);

# app/client/src/state/readOneMyVersionedObjectQuery.js
 import { graphql } from 'react-apollo';
 import gql from 'graphql-tag';

-// Note that "readOneMyVersionedObject" is the query name in the schema, while
+// Note that "readOneAppMyVersionedObject" is the query name in the schema, while
 // "ReadHistoryViewerMyVersionedObject" is an arbitrary name we're using for this invocation
 // of the query
 const query = gql`
 query ReadHistoryViewerMyVersionedObject ($id: ID!, $limit: Int!, $offset: Int!) {
-    readOneMyVersionedObject(
+    readOneAppMyVersionedObject(
       versioning: {
         mode: ALL_VERSIONS
       },
-      filter: {
-        id: { eq: $id }
-      }
+      id: $id
     ) {
       id
       versions (limit: $limit, offset: $offset, sort: {

...

     data: {
       error,
       refetch,
-       readOneMyVersionedObject,
+       readOneAppMyVersionedObject,
       loading: networkLoading,
     },
     ownProps: {

...

       recordId,
     },
   }) {
-    const versions = readOneMyVersionedObject || null;
+    const versions = readOneAppMyVersionedObject || null;

     const errors = error && error.graphQLErrors &&

...

# app/client/src/state/revertToMyVersionedObjectVersionMutation.js
 import { graphql } from 'react-apollo';
 import gql from 'graphql-tag';

-// Note that "rollbackMyVersionedObject" is the mutation name in the schema, while
+// Note that "rollbackAppMyVersionedObject" is the mutation name in the schema, while
 // "revertToMyVersionedObject" is an arbitrary name we're using for this invocation
 // of the mutation
 const mutation = gql`
 mutation revertToMyVersionedObject($id:ID!, $toVersion:Int!) {
-  rollbackMyVersionedObject(
+  rollbackAppMyVersionedObject(
     id: $id
     toVersion: $toVersion
   ) {
...

Register your GraphQL query and mutation with Injector#

Regardless of which version of silverstripe/graphql you're using, once your GraphQL query and mutation are created you will need to tell the JavaScript Injector about them. This does two things:

• Allow them to be loaded by core components.
• Allow Injector to provide them in certain contexts. They should be available for MyVersionedObject history viewer instances, but not for CMS pages for example.

// app/client/src/boot/index.js

/* global window */
import Injector from 'lib/Injector';
import readOneMyVersionedObjectQuery from 'state/readOneMyVersionedObjectQuery';
import revertToMyVersionedObjectVersionMutation from 'state/revertToMyVersionedObjectVersionMutation';

window.document.addEventListener('DOMContentLoaded', () => {
  // Register GraphQL operations with Injector as transformations
  Injector.transform(
    'myversionedobject-history', // this name is arbitrary
    (updater) => {
      // Add CMS page history GraphQL query to the HistoryViewer
      updater.component(
        'HistoryViewer.Form_ItemEditForm',
        readOneMyVersionedObjectQuery,
        'MyVersionedObjectHistoryViewer' // this name is arbitrary
      );
    }
  );

  Injector.transform(
    'myversionedobject-history-revert', // this name is arbitrary
    (updater) => {
      // Add CMS page revert GraphQL mutation to the HistoryViewerToolbar
      updater.component(
        // NOTE: The "App_MyVersionedObject" portion here is taken from table_name of the model
        'HistoryViewerToolbar.VersionedAdmin.HistoryViewer.App_MyVersionedObject.HistoryViewerVersionDetail',
        revertToMyVersionedObjectVersionMutation,
        'MyVersionedObjectRevertMutation' // this name is arbitrary
      );
    }
  );
});

For more information, see Using Injector to customise GraphQL queries and Transforming services using middleware.

Adding the HistoryViewerField#

Firstly, ensure your JavaScript bundle is included throughout the CMS:

---
Name: CustomAdmin
After:
  - 'versionedadmincmsconfig'
  - 'versionededitform'
  - 'cmsscripts'
  - 'elemental' # Only needed if silverstripe-elemental is installed
---
SilverStripe\Admin\LeftAndMain:
  extra_requirements_javascript:
    - app/client/dist/js/bundle.js

Then you can add the HistoryViewerField to your model's CMS fields in the same way as any other form field:

use SilverStripe\VersionedAdmin\Forms\HistoryViewerField;

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

Previewable DataObject models#

The history viewer will automatically detect and render a side-by-side preview panel for DataObjects that implement CMSPreviewable. Please note that if you are adding this functionality, you will also need to expose the AbsoluteLink field in your GraphQL read scaffolding, and add it to the fields in readOneMyVersionedObjectQuery.

API documentation#

• Versioned
• HistoryViewerField