Blocks

"Block" is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage. The idea combines concepts of what in GeChiUI today we achieve with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience.

For more context, refer to What Are Little Blocks Made Of? from the Make GeChiUI Design blog.

The following documentation outlines steps you as a developer will need to follow to add your own custom blocks to GeChiUI's editor interfaces.

Installation

Install the module

npm install @gechiui/blocks --save

This package assumes that your code will run in an ES2015+ environment. If you're using an environment that has limited or no support for such language features and APIs, you should include the polyfill shipped in @gechiui/babel-preset-default in your code.

Getting Started

If you're not already accustomed to working with JavaScript in your GeChiUI plugins, you may first want to reference the guide on Including CSS & JavaScript in the Theme Handbook.

At a minimum, you will need to enqueue scripts for your block as part of a enqueue_block_editor_assets action callback, with a dependency on the gc-blocks and gc-element script handles:

<?php
// myplugin.php

function myplugin_enqueue_block_editor_assets() {
	gc_enqueue_script(
		'myplugin-block',
		plugins_url( 'block.js', __FILE__ ),
		array( 'gc-blocks', 'gc-element' )
	);
}
add_action( 'enqueue_block_editor_assets', 'myplugin_enqueue_block_editor_assets' );

The enqueue_block_editor_assets hook is only run in the Gutenberg editor context when the editor is ready to receive additional scripts and stylesheets. There is also an enqueue_block_assets hook which is run under both the editor and front-end contexts. This should be used to enqueue stylesheets common to the front-end and the editor. (The rules can be overridden in the editor-specific stylesheet if necessary.)

The following sections will describe what you'll need to include in block.js to describe the behavior of your custom block.

Note that all JavaScript code samples in this document are enclosed in a function that is evaluated immediately afterwards. We recommend using either ES6 modules as used in this project (documentation on setting up a plugin with Webpack + ES6 modules coming soon) or these "immediately-invoked function expressions" as used in this document. Both of these methods ensure that your plugin's variables will not pollute the global window object, which could cause incompatibilities with GeChiUI core or with other plugins.

Example

Let's imagine you wanted to define a block to show a randomly generated image in a post's content using lorempixel.com. The service provides a choice of category and you'd like to offer this as an option when editing the post.

Take a step back and consider the ideal workflow for adding a new random image:

• Insert the block. It should be shown in some empty state, with an option to choose a category in a select dropdown.
• Upon confirming my selection, a preview of the image should be shown next to the dropdown.

At this point, you might realize that while you'd want some controls to be shown when editing content, the markup included in the published post might not appear the same (your visitors should not see a dropdown field when reading your content).

This leads to the first requirement of describing a block:

You will need to provide implementations both for what's to be shown in an editor and what's to be saved with the published content.

To eliminate redundant effort here, share common behaviors by splitting your code up into components.

Now that we've considered user interaction, you should think about the underlying values that determine the markup generated by your block. In our example, the output is affected only when the category changes. Put another way: the output of a block is a function of its attributes.

The category, a simple string, is the only thing we require to be able to generate the image we want to include in the published content. We call these underlying values of a block instance its attributes.

With these concepts in mind, let's explore an implementation of our random image block:

<?php
// random-image.php

function random_image_enqueue_block_editor_assets() {
	gc_enqueue_script(
		'random-image-block',
		plugins_url( 'block.js', __FILE__ ),
		array( 'gc-blocks', 'gc-element', 'gc-block-editor', )
	);
}
add_action( 'enqueue_block_editor_assets', 'random_image_enqueue_block_editor_assets' );

// block.js
( function ( blocks, element, blockEditor ) {
	var el = element.createElement,
		source = blocks.source,
		useBlockProps = blockEditor.useBlockProps;

	function RandomImage( props ) {
		var src = 'http://lorempixel.com/400/200/' + props.category;

		return el( 'img', {
			src: src,
			alt: props.category,
		} );
	}

	blocks.registerBlockType( 'myplugin/random-image', {
		apiVersion: 2,

		title: 'Random Image',

		icon: 'format-image',

		category: 'text',

		attributes: {
			category: {
				type: 'string',
				source: 'attribute',
				attribute: 'alt',
				selector: 'img',
			},
		},

		edit: function ( props ) {
			var blockProps = useBlockProps();
			var category = props.attributes.category,
				children;

			function setCategory( event ) {
				var selected = event.target.querySelector( 'option:checked' );
				props.setAttributes( { category: selected.value } );
				event.preventDefault();
			}

			children = [];
			if ( category ) {
				children.push( RandomImage( { category: category } ) );
			}

			children.push(
				el(
					'select',
					{ value: category, onChange: setCategory },
					el( 'option', null, '- Select -' ),
					el( 'option', { value: 'sports' }, 'Sports' ),
					el( 'option', { value: 'animals' }, 'Animals' ),
					el( 'option', { value: 'nature' }, 'Nature' )
				)
			);

			return el(
				'form',
				Object.assign( blockProps, { onSubmit: setCategory } ),
				children
			);
		},

		save: function ( props ) {
			return RandomImage( { category: props.attributes.category } );
		},
	} );
} )( window.gc.blocks, window.gc.element, window.gc.blockEditor );

(Example in ES2015+, JSX)

Let's briefly review a few items you might observe in the implementation:

• When registering a new block, you must prefix its name with a namespace for your plugin. This helps prevent conflicts when more than one plugin registers a block with the same name.
• You will use createElement to describe the structure of your block's markup. See the Element documentation for more information.
• Extracting RandomImage to a separate function allows us to reuse it in both the editor-specific interface and the published content.
• The edit function should handle any case where an attribute is unset, as in the case of the block being newly inserted.
• We only change the attributes of a block by calling the setAttributes helper. Never assign a value on the attributes object directly.
• React provides conveniences for working with select element with value and onChange props.

By concerning yourself only with describing the markup of a block given its attributes, you need not worry about maintaining the state of the page, or how your block interacts in the context of the surrounding editor.

But how does the markup become an object of attributes? We need a pattern for encoding the values into the published post's markup, and then retrieving them the next time the post is edited. This is the motivation for the block's attributes property. The shape of this object matches that of the attributes object we'd like to receive, where each value is a source which tries to find the desired value from the markup of the block.

In the random image block above, we've given the alt attribute of the image a secondary responsibility of tracking the selected category. There are a few other ways we could have achieved this, but the category value happens to work well as an alt descriptor. In the attributes property, we define an object with a key of category whose value tries to find this alt attribute of the markup. If it's successful, the category's value in our edit and save functions will be assigned. In the case of a new block or invalid markup, this value would be undefined, so we adjust our return value accordingly.

API

cloneBlock

Given a block object, returns a copy of the block object, optionally merging new attributes and/or replacing its inner blocks.

Parameters

• block Object: Block instance.
• mergeAttributes Object: Block attributes.
• newInnerBlocks ?Array: Nested blocks.

Returns

• Object: A cloned block.

createBlock

Returns a block object given its type and attributes.

Parameters

• name string: Block name.
• attributes Object: Block attributes.
• innerBlocks ?Array: Nested blocks.

Returns

• Object: Block object.

createBlocksFromInnerBlocksTemplate

Given an array of InnerBlocks templates or Block Objects, returns an array of created Blocks from them. It handles the case of having InnerBlocks as Blocks by converting them to the proper format to continue recursively.

Parameters

• innerBlocksOrTemplate Array: Nested blocks or InnerBlocks templates.

Returns

• Object[]: Array of Block objects.

doBlocksMatchTemplate

Checks whether a list of blocks matches a template by comparing the block names.

Parameters

• blocks Array: Block list.
• template Array: Block template.

Returns

• boolean: Whether the list of blocks matches a templates.

findTransform

Given an array of transforms, returns the highest-priority transform where the predicate function returns a truthy value. A higher-priority transform is one with a lower priority value (i.e. first in priority order). Returns null if the transforms set is empty or the predicate function returns a falsey value for all entries.

Parameters

• transforms Object[]: Transforms to search.
• predicate Function: Function returning true on matching transform.

Returns

• ?Object: Highest-priority transform candidate.

getBlockAttributes

Returns the block attributes of a registered block node given its type.

Parameters

• blockTypeOrName string|Object: Block type or name.
• innerHTML string: Raw block content.
• attributes ?Object: Known block attributes (from delimiters).

Returns

• Object: All block attributes.

getBlockContent

Given a block object, returns the Block's Inner HTML markup.

Parameters

• block Object: Block instance.

Returns

• string: HTML.

getBlockDefaultClassName

Returns the block's default classname from its name.

Parameters

• blockName string: The block name.

Returns

• string: The block's default class.

getBlockFromExample

Create a block object from the example API.

Parameters

• name string:
• example Object:

Returns

• Object: block.

getBlockMenuDefaultClassName

Returns the block's default menu item classname from its name.

Parameters

• blockName string: The block name.

Returns

• string: The block's default menu item class.

getBlockSupport

Returns the block support value for a feature, if defined.

Parameters

• nameOrType (string|Object): Block name or type object
• feature string: Feature to retrieve
• defaultSupports *: Default value to return if not explicitly defined

Returns

• ?*: Block support value

getBlockTransforms

Returns normal block transforms for a given transform direction, optionally for a specific block by name, or an empty array if there are no transforms. If no block name is provided, returns transforms for all blocks. A normal transform object includes blockName as a property.

Parameters

• direction string: Transform direction ("to", "from").
• blockTypeOrName string|Object: Block type or name.

Returns

• Array: Block transforms for direction.

getBlockType

Returns a registered block type.

Parameters

• name string: Block name.

Returns

• ?Object: Block type.

getBlockTypes

Returns all registered blocks.

Returns

• Array: Block settings.

getBlockVariations

Returns an array with the variations of a given block type.

Parameters

• blockName string: Name of block (example: “core/columns”).
• scope [GCBlockVariationScope]: Block variation scope name.

Returns

• (GCBlockVariation[]|void): Block variations.

getCategories

Returns all the block categories.

Returns

• GCBlockCategory[]: Block categories.

getChildBlockNames

Returns an array with the child blocks of a given block.

Parameters

• blockName string: Name of block (example: “latest-posts”).

Returns

• Array: Array of child block names.

getDefaultBlockName

Retrieves the default block name.

Returns

• ?string: Block name.

getFreeformContentHandlerName

Retrieves name of block handling non-block content, or undefined if no handler has been defined.

Returns

• ?string: Block name.

getGroupingBlockName

Retrieves name of block used for handling grouping interactions.

Returns

• ?string: Block name.

getPhrasingContentSchema

Undocumented declaration.

getPossibleBlockTransformations

Returns an array of block types that the set of blocks received as argument can be transformed into.

Parameters

• blocks Array: Blocks array.

Returns

• Array: Block types that the blocks argument can be transformed to.

getSaveContent

Given a block type containing a save render implementation and attributes, returns the static markup to be saved.

Parameters

• blockTypeOrName string|Object: Block type or name.
• attributes Object: Block attributes.
• innerBlocks ?Array: Nested blocks.

Returns

• string: Save content.

getSaveElement

Given a block type containing a save render implementation and attributes, returns the enhanced element to be saved or string when raw HTML expected.

Parameters

• blockTypeOrName string|Object: Block type or name.
• attributes Object: Block attributes.
• innerBlocks ?Array: Nested blocks.

Returns

• Object|string: Save element or raw HTML string.

getUnregisteredTypeHandlerName

Retrieves name of block handling unregistered block types, or undefined if no handler has been defined.

Returns

• ?string: Block name.

hasBlockSupport

Returns true if the block defines support for a feature, or false otherwise.

Parameters

• nameOrType (string|Object): Block name or type object.
• feature string: Feature to test.
• defaultSupports boolean: Whether feature is supported by default if not explicitly defined.

Returns

• boolean: Whether block supports feature.

hasChildBlocks

Returns a boolean indicating if a block has child blocks or not.

Parameters

• blockName string: Name of block (example: “latest-posts”).

Returns

• boolean: True if a block contains child blocks and false otherwise.

hasChildBlocksWithInserterSupport

Returns a boolean indicating if a block has at least one child block with inserter support.

Parameters

• blockName string: Block type name.

Returns

• boolean: True if a block contains at least one child blocks with inserter support and false otherwise.

isReusableBlock

Determines whether or not the given block is a reusable block. This is a special block type that is used to point to a global block stored via the API.

Parameters

• blockOrType Object: Block or Block Type to test.

Returns

• boolean: Whether the given block is a reusable block.

isTemplatePart

Determines whether or not the given block is a template part. This is a special block type that allows composing a page template out of reusable design elements.

Parameters

• blockOrType Object: Block or Block Type to test.

Returns

• boolean: Whether the given block is a template part.

isUnmodifiedDefaultBlock

Determines whether the block is a default block and its attributes are equal to the default attributes which means the block is unmodified.

Parameters

• block GCBlock: Block Object

Returns

• boolean: Whether the block is an unmodified default block

isValidBlockContent

Returns true if the parsed block is valid given the input content. A block is considered valid if, when serialized with assumed attributes, the content matches the original value.

Logs to console in development environments when invalid.

Parameters

• blockTypeOrName string|Object: Block type.
• attributes Object: Parsed block attributes.
• originalBlockContent string: Original block content.

Returns

• boolean: Whether block is valid.

isValidIcon

Function that checks if the parameter is a valid icon.

Parameters

• icon *: Parameter to be checked.

Returns

• boolean: True if the parameter is a valid icon and false otherwise.

normalizeIconObject

Function that receives an icon as set by the blocks during the registration and returns a new icon object that is normalized so we can rely on just on possible icon structure in the codebase.

Parameters

• icon GCBlockTypeIconRender: Render behavior of a block type icon; one of a Dashicon slug, an element, or a component.

Returns

• GCBlockTypeIconDescriptor: Object describing the icon.

parse

Utilizes an optimized token-driven parser based on the Gutenberg grammar spec defined through a parsing expression grammar to take advantage of the regular cadence provided by block delimiters -- composed syntactically through HTML comments -- which, given a general HTML document as an input, returns a block list array representation.

This is a recursive-descent parser that scans linearly once through the input document. Instead of directly recursing it utilizes a trampoline mechanism to prevent stack overflow. This initial pass is mainly interested in separating and isolating the blocks serialized in the document and manifestly not in the content within the blocks.

Related

• https://developer.gechiui.com/block-editor/packages/packages-block-serialization-default-parser/

Parameters

• content string: The post content.

Returns

• Array: Block list.

parseWithAttributeSchema

Given a block's raw content and an attribute's schema returns the attribute's value depending on its source.

Parameters

• innerHTML string: Block's raw content.
• attributeSchema Object: Attribute's schema.

Returns

• *: Attribute value.

pasteHandler

Converts an HTML string to known blocks. Strips everything else.

Parameters

• options Object:
• options.HTML [string]: The HTML to convert.
• options.plainText [string]: Plain text version.
• options.mode [string]: Handle content as blocks or inline content. _ 'AUTO': Decide based on the content passed. _ 'INLINE': Always handle as inline content, and return string. * 'BLOCKS': Always handle as blocks, and return array of blocks.
• options.tagName [Array]: The tag into which content will be inserted.
• options.preserveWhiteSpace [boolean]: Whether or not to preserve consequent white space.

Returns

• Array|string: A list of blocks or a string, depending on handlerMode.

rawHandler

Converts an HTML string to known blocks.

Parameters

• $1 Object:
• $1.HTML string: The HTML to convert.

Returns

• Array: A list of blocks.

registerBlockCollection

Registers a new block collection to group blocks in the same namespace in the inserter.

Parameters

• namespace string: The namespace to group blocks by in the inserter; corresponds to the block namespace.
• settings Object: The block collection settings.
• settings.title string: The title to display in the block inserter.
• settings.icon [Object]: The icon to display in the block inserter.

registerBlockStyle

Registers a new block style variation for the given block.

Parameters

• blockName string: Name of block (example: “core/latest-posts”).
• styleVariation Object: Object containing name which is the class name applied to the block and label which identifies the variation to the user.

registerBlockType

Registers a new block provided a unique name and an object defining its behavior. Once registered, the block is made available as an option to any editor interface where blocks are implemented.

Parameters

• blockNameOrMetadata string|Object: Block type name or its metadata.
• settings Object: Block settings.

Returns

• ?GCBlockType: The block, if it has been successfully registered; otherwise undefined.

registerBlockVariation

Registers a new block variation for the given block type.

Parameters

• blockName string: Name of the block (example: “core/columns”).
• variation GCBlockVariation: Object describing a block variation.

serialize

Takes a block or set of blocks and returns the serialized post content.

Parameters

• blocks Array: Block(s) to serialize.
• options GCBlockSerializationOptions: Serialization options.

Returns

• string: The post content.

setCategories

Sets the block categories.

Parameters

• categories GCBlockCategory[]: Block categories.

setDefaultBlockName

Assigns the default block name.

Parameters

• name string: Block name.

setFreeformContentHandlerName

Assigns name of block for handling non-block content.

Parameters

• blockName string: Block name.

setGroupingBlockName

Assigns name of block for handling block grouping interactions.

Parameters

• name string: Block name.

setUnregisteredTypeHandlerName

Assigns name of block handling unregistered block types.

Parameters

• blockName string: Block name.

store

Store definition for the blocks namespace.

Related

• https://github.com/GeChiUI/gutenberg/blob/HEAD/packages/data/README.md#createReduxStore

Type

• Object

switchToBlockType

Switch one or more blocks into one or more blocks of the new block type.

Parameters

• blocks Array|Object: Blocks array or block object.
• name string: Block name.

Returns

• ?Array: Array of blocks or null.

synchronizeBlocksWithTemplate

Synchronize a block list with a block template.

Synchronizing a block list with a block template means that we loop over the blocks keep the block as is if it matches the block at the same position in the template (If it has the same name) and if doesn't match, we create a new block based on the template. Extra blocks not present in the template are removed.

Parameters

• blocks Array: Block list.
• template Array: Block template.

Returns

• Array: Updated Block list.

unregisterBlockStyle

Unregisters a block style variation for the given block.

Parameters

• blockName string: Name of block (example: “core/latest-posts”).
• styleVariationName string: Name of class applied to the block.

unregisterBlockType

Unregisters a block.

Parameters

• name string: Block name.

Returns

• ?GCBlockType: The previous block value, if it has been successfully unregistered; otherwise undefined.

unregisterBlockVariation

Unregisters a block variation defined for the given block type.

Parameters

• blockName string: Name of the block (example: “core/columns”).
• variationName string: Name of the variation defined for the block.

updateCategory

Updates a category.

Parameters

• slug string: Block category slug.
• category GCBlockCategory: Object containing the category properties that should be updated.

withBlockContentContext

A Higher Order Component used to inject BlockContent using context to the wrapped component.

Returns

• GCComponent: Enhanced component with injected BlockContent as prop.

Contributing to this package

This is an individual package that's part of the Gutenberg project. The project is organized as a monorepo. It's made up of multiple self-contained software packages, each with a specific purpose. The packages in this monorepo are published to npm and used by GeChiUI as well as other software projects.

To find out more about contributing to this package or Gutenberg as a whole, please read the project's main contributor guide.