mirror of
https://github.com/silverstripe/silverstripe-framework
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188 lines
6.8 KiB
Markdown
188 lines
6.8 KiB
Markdown
# CMS preview
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## Overview
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With the addition of side-by-side editing, the preview has the ability to appear
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within the CMS window when editing content in the _Pages_ section of the CMS.
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The site is rendered into an iframe. It will update itself whenever the content
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is saved, and relevant pages will be loaded for editing when the user navigates
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around in the preview.
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The root element for preview is `.cms-preview` which maintains the internal
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states necessary for rendering within the entwine properties. It provides
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function calls for transitioning between these states and has the ability to
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update the appearance of the option selectors.
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In terms of backend support, it relies on `SilverStripeNavigator` to be rendered
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into the `.cms-edit-form`. _LeftAndMain_ will automatically take care of
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generating it as long as the `*_SilverStripeNavigator` template is found -
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first segment has to match current _LeftAndMain_-derived class (e.g.
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`LeftAndMain_SilverStripeNavigator`).
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We use `ss.preview` entwine namespace for all preview-related entwines.
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<div class="notice" markdown='1'>
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Caveat: `SilverStripeNavigator` and `CMSPreviewable` interface currently only
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support SiteTree objects that are _Versioned_. They are not general enough for
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using on any other DataObject. That pretty much limits the extendability of the
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feature.
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</div>
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## Configuration and Defaults
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Like most of the CMS, the preview UI is powered by
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[jQuery entwine](https://github.com/hafriedlander/jquery.entwine). This means
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its defaults are configured through JavaScript, by setting entwine properties.
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In order to achieve this, create a new file `mysite/javascript/MyLeftAndMain.Preview.js`.
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In the following example we configure three aspects:
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* Set the default mode from "split view" to a full "edit view"
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* Make a wider mobile preview
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* Increase minimum space required by preview before auto-hiding
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Note how the configuration happens in different entwine namespaces
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("ss.preview" and "ss"), as well as applies to different selectors
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(".cms-preview" and ".cms-container").
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:::js
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(function($) {
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$.entwine('ss.preview', function($){
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$('.cms-preview').entwine({
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DefaultMode: 'content',
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getSizes: function() {
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var sizes = this._super();
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sizes.mobile.width = '400px';
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return sizes;
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}
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});
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});
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$.entwine('ss', function($){
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$('.cms-container').entwine({
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getLayoutOptions: function() {
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var opts = this._super();
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opts.minPreviewWidth = 600;
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return opts;
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}
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});
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});
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}(jQuery));
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Load the file in the CMS via setting adding 'mysite/javascript/MyLeftAndMain.Preview.js'
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to the `LeftAndMain.extra_requirements_javascript` [configuration value](/topics/configuration)
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:::yml
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LeftAndMain
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extra_requirements_javascript:
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- mysite/javascript/MyLeftAndMain.Preview.js:
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In order to find out which configuration values are available, the source code
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is your best reference at the moment - have a look in `framework/admin/javascript/LeftAndMain.Preview.js`.
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To understand how layouts are handled in the CMS UI, have a look at the
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[CMS Architecture](/reference/cms-architecture) guide.
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## Enabling preview
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The frontend decides on the preview being enabled or disabled based on the
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presence of the `.cms-previewable` class. If this class is not found the preview
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will remain hidden, and the layout will stay in the _content_ mode.
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If the class is found, frontend looks for the `SilverStripeNavigator` structure
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and moves it to the `.cms-preview-control` panel at the bottom of the preview.
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This structure supplies preview options such as state selector.
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If the navigator is not found, the preview appears in the GUI, but is shown as
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"blocked" - i.e. displaying the "preview unavailable" overlay.
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The preview can be affected by calling `enablePreview` and `disablePreview`. You
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can check if the preview is active by inspecting the `IsPreviewEnabled` entwine
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property.
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## Preview states
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States are the site stages: _live_, _stage_ etc. Preview states are picked up
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from the `SilverStripeNavigator`. You can invoke the state change by calling:
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```js
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$('.cms-preview').entwine('.ss.preview').changeState('StageLink');
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```
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Note the state names come from `SilverStripeNavigatorItems` class names - thus
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the _Link_ in their names. This call will also redraw the state selector to fit
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with the internal state. See `AllowedStates` in `.cms-preview` entwine for the
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list of supported states.
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You can get the current state by calling:
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```js
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$('.cms-preview').entwine('.ss.preview').getCurrentStateName();
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```
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## Preview sizes
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This selector defines how the preview iframe is rendered, and try to emulate
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different device sizes. The options are hardcoded. The option names map directly
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to CSS classes applied to the `.cms-preview` and are as follows:
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* _auto_: responsive layout
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* _desktop_
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* _tablet_
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* _mobile_
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You can switch between different types of display sizes programmatically, which
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has the benefit of redrawing the related selector and maintaining a consistent
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internal state:
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```js
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$('.cms-preview').entwine('.ss.preview').changeSize('auto');
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```
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You can find out current size by calling:
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```js
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$('.cms-preview').entwine('.ss.preview').getCurrentSizeName();
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```
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## Preview modes
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Preview modes map to the modes supported by the _threeColumnCompressor_ layout
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algorithm, see [layout reference](../reference/layout) for more details. You
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can change modes by calling:
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```js
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$('.cms-preview').entwine('.ss.preview').changeMode('preview');
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```
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Currently active mode is stored on the `.cms-container` along with related
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internal states of the layout. You can reach it by calling:
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```js
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$('.cms-container').entwine('.ss').getLayoutOptions().mode;
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```
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<div class="notice" markdown='1'>
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Caveat: the `.preview-mode-selector` appears twice, once in the preview and
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second time in the CMS actions area as `#preview-mode-dropdown-in-cms`. This is
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done because the user should still have access to the mode selector even if
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preview is not visible. Currently CMS Actions are a separate area to the preview
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option selectors, even if they try to appear as one horizontal bar.
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</div>
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## Preview API
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Namespace `ss.preview`, selector `.cms-preview`:
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* **getCurrentStateName**: get the name of the current state (e.g. _LiveLink_ or _StageLink_).
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* **getCurrentSizeName**: get the name of the current device size.
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* **getIsPreviewEnabled**: check if the preview is enabled.
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* **changeState**: one of the `AllowedStates`.
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* **changeSize**: one of _auto_, _desktop_, _tablet_, _mobile_.
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* **changeMode**: maps to _threeColumnLayout_ modes - _split_, _preview_, _content_.
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* **enablePreview**: activate the preview and switch to the _split_ mode. Try to load the relevant URL from the content.
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* **disablePreview**: deactivate the preview and switch to the _content_ mode. Preview will re-enable itself when new
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previewable content is loaded.
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## Related
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* [Reference: Layout](../reference/layout)
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