250 lines
8.1 KiB
Markdown
250 lines
8.1 KiB
Markdown
# Extending Netlify CMS
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The Netlify CMS exposes an `window.CMS` global object that you can use to register custom widgets, previews and editor plugins. The available methods are:
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* **registerPreviewStyle** Register a custom stylesheet to use on the preview pane.
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* **registerPreviewTemplate** Registers a template for a collection.
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* **registerWidget** lets you register a custom widget.
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* **registerEditorComponent** lets you add a block component to the Markdown editor
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**Writing React Components inline**
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Both registerPreviewTemplate and registerWidget requires you to provide a React component. If you have a build process in place for your project, it is possible to integrate webpack and Babel for a complete React build flow.
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Although possible, it may be cumbersome or even impractical to add a React build phase. For this reason, Netlify CMS exposes two React constructs globally to allow you to create components inline: ‘createClass’ and ‘h’ (alias for React.createElement).
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## `registerPreviewStyle`
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Register a custom stylesheet to use on the preview pane.
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`CMS.registerPreviewStyle(file);`
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**Params:**
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* file: css file path.
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**Example:**
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`CMS.registerPreviewStyle("/example.css");`
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## `registerPreviewTemplate`
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Registers a template for a collection.
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`CMS.registerPreviewTemplate(collection, react_component);`
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**React Component Props:**
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* collection: The name of the collection which this preview component will be used for.
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* react_component: A React component that renders the collection data. Four props will be passed to your component during render:
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* entry: Immutable collection containing the entry data.
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* widgetFor: Returns the appropriate widget preview component for a given field.
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* [widgetsFor](#lists-and-objects): Returns an array of objects with widgets and associated field data. For use with list and object type entries.
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* getAsset: Returns the correct filePath or in-memory preview for uploaded images.
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**Example:**
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```html
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<script>
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var PostPreview = createClass({
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render: function() {
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var entry = this.props.entry;
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var image = entry.getIn(['data', 'image']);
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var bg = this.props.getAsset(image);
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return h('div', {},
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h('h1', {}, entry.getIn(['data', 'title'])),
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h('img', {src: bg.toString()}),
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h('div', {"className": "text"}, this.props.widgetFor('body'))
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);
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}
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});
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CMS.registerPreviewTemplate("posts", PostPreview);
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</script>
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```
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### Lists and Objects
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The API for accessing the individual fields of list and object type entries is similar to the API
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for accessing fields in standard entries, but there are a few key differences. Access to these
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nested fields is facilitated through the `widgetsFor` function, which is passed to the preview
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template component during render.
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**Note**: as is often the case with the Netlify CMS API, arrays and objects are created with
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Immutable.js. If some of the methods that we use are unfamiliar, such as `getIn`, check out
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[their docs](https://facebook.github.io/immutable-js/docs/#/) to get a better understanding.
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**List Example:**
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```html
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<script>
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var AuthorsPreview = createClass({
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// For list fields, the widgetFor function returns an array of objects
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// which you can map over in your template. If our field is a list of
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// authors containing two entries, with fields `name` and `description`,
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// the return value of `widgetsFor` would look like this:
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//
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// [{
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// data: { name: 'Mathias', description: 'Co-Founder'},
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// widgets: { name: (<WidgetComponent>), description: (WidgetComponent>)}
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// },
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// {
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// data: { name: 'Chris', description: 'Co-Founder'},
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// widgets: { name: (<WidgetComponent>), description: (WidgetComponent>)}
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// }]
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//
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// Templating would look something like this:
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render: function() {
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return h('div', {},
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// This is a static header that would only be rendered once for the entire list
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h('h1', {}, 'Authors'),
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// Here we provide a simple mapping function that will be applied to each
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// object in the array of authors
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this.props.widgetsFor('authors').map(function(author, index) {
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return h('div', {key: index},
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h('hr', {}),
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h('strong', {}, author.getIn(['data', 'name'])),
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author.getIn(['widgets', 'description'])
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);
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})
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);
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}
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});
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CMS.registerPreviewTemplate("authors", AuthorsPreview);
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</script>
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```
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**Object Example:**
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```html
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<script>
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var GeneralPreview = createClass({
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// Object fields are simpler than lists - instead of `widgetsFor` returning
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// an array of objects, it returns a single object. Accessing the shape of
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// that object is the same as the shape of objects returned for list fields:
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//
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// {
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// data: { front_limit: 0, author: 'Chris' },
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// widgets: { front_limit: (<WidgetComponent>), author: (WidgetComponent>)}
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// }
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render: function() {
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var entry = this.props.entry;
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var title = entry.getIn(['data', 'site_title']);
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var posts = entry.getIn(['data', 'posts']);
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return h('div', {},
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h('h1', {}, title),
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h('dl', {},
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h('dt', {}, 'Posts on Frontpage'),
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h('dd', {}, this.props.widgetsFor('posts').getIn(['widgets', 'front_limit']) || 0),
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h('dt', {}, 'Default Author'),
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h('dd', {}, this.props.widgetsFor('posts').getIn(['data', 'author']) || 'None'),
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)
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);
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}
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});
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CMS.registerPreviewTemplate("general", GeneralPreview);
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</script>
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```
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### Accessing Metadata
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Preview Components also receive an additional prop: `fieldsMetaData`. It contains aditional information (besides the plain plain textual value of each field) that can be useful for preview purposes.
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For example, the Relation widget passes the whole selected relation data in fieldsMetaData.
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```js
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export default class ArticlePreview extends React.Component {
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render() {
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const {entry, fieldsMetaData} = this.props;
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const author = fieldsMetaData.getIn(['authors', data.author]);
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return <article>
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<h2>{ entry.getIn(['data', 'title']) }</h2>
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{author && <AuthorBio author={author.toJS()}/>}
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</article>
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}
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}
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```
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## `registerWidget`
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lets you register a custom widget.
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`CMS.registerWidget(field, control, [preview])`
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**Params:**
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* field: The field type which this widget will be used for.
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* control: A React component that renders the editing interface for this field. Two props will be passed:
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* value: The current value for this field.
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* onChange: Callback function to update the field value.
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* preview (optional): A React component that renders the preview of how the content will look. A `value` prop will be passed to this component.
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**Example:**
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```html
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<script>
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var CategoriesControl = createClass({
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handleChange: function(e) {
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this.props.onChange(e.target.value.split(',').map((e) => e.trim()));
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},
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render: function() {
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var value = this.props.value;
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return h('input', { type: 'text', value: value ? value.join(', ') : '', onChange: this.handleChange });
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}
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});
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CMS.registerWidget('categories', CategoriesControl);
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</script>
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```
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## `registerEditorComponent`
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lets your register a block level component for the Markdown editor
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`CMS.registerEditorComponent(definition)`
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**Params**
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* definition: The component definition, must specify: id, label, fields, patterns, fromBlock, toBlock, toPreview
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**Example:**
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```js
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CMS.registerEditorComponent({
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// Internal id of the component
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id: "youtube",
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// Visible label
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label: "Youtube",
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// Fields the user need to fill out when adding an instance of the component
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fields: [{name: 'id', label: 'Youtube Video ID', widget: 'string'}],
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// Pattern to identify a block as being an instance of this component
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pattern: /^{{<\s?youtube (\S+)\s?>}}/,
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// Function to extract data elements from the regexp match
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fromBlock: function(match) {
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return {
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id: match[1]
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};
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},
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// Function to create a text block from an instance of this component
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toBlock: function(obj) {
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return '{{< youtube ' + obj.id + ' >}}';
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},
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// Preview output for this component. Can either be a string or a React component
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// (Component gives better render performance)
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toPreview: function(obj) {
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return (
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'<img src="http://img.youtube.com/vi/' + obj.id + '/maxresdefault.jpg" alt="Youtube Video"/>'
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);
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}
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});
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```
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