內容簡介
這個外掛程式協助將 WordPress 轉變為數位內容管理員，以便在不同的媒介或平台 (不僅是網站，還包括電子郵件、iOS/Android 應用程式、家庭助理 (例如 Amazon Alexa) 等) 上發佈內容。
它透過萃取網誌文章中所有 Gutenberg 區塊的 metadata 來達成這個目的。由於每個 Gutenberg 區塊都儲存自己的內容和屬性，因此可以將這些屬性提取為 metadata 並導出為 JSON 物件。透過 REST API 端點存取此 JSON 物件，即可饋入任何平台上的任何應用程式。
這個外掛程式提供以下 REST API 端點：
/wp-json/block-metadata/v1/metadata/{POST_ID}：從 id 為 {POST_ID} 的網誌文章中，萃取所有 Gutenberg 區塊的 metadata，轉換為中立於媒體之上的格式 (例如刪除所有非語義 HTML 標籤)
/wp-json/block-metadata/v1/data/{POST_ID}：從 id 為 {POST_ID} 的網誌文章中，萃取所有 Gutenberg 區塊中原始存放於區塊中的內容資料 (例如包含 HTML code)
示範如下：
網誌文章
網誌文章的 Gutenberg 區塊
網誌文章的中立於媒體之上的 metadata
它是如何運作的？
此外掛程式是基於「創建一次，多處發佈訊息」(稱為 COPE) 的策略，由建立一個單一的內容真相來降低在不同媒體中發佈內容所需的工作量。
讓內容能夠在各處順利顯示並不是一件簡單的事，因為每個媒體都有自己的需求。例如，HTML 可以用於將內容列印在網站上，但是這種語言則不適用於 iOS/Android 應用程式；同樣的，我們可以為網站的 HTML 增加 class，但是這些必須轉換成 email 的樣式。
解決方案是將表格和內容分離：表現形式和內容本身的意義必須解耦只有以意義為單一認識點。而表現形式可以在另一層特定於所選取的媒體中加入。例如，對於下列的 HTML code，<p> 是一個 HTML 標籤，對於網站而言，它主要應用於此；而屬性 class=”align-center” 則是表演（將元素置中對於基於屏幕的媒體是有意義的，但是對於 Amazon Alexa 這樣的聲音媒體則不是）：
<p class="align-center">Hello world!</p>
因此，這一段內容不能被當做單一認識點；它必須轉換為另一種格式，將表現形式與內容分離，像下面的 JSON code 片斷：
{
content: "Hello world!",
placement: "center",
type: "paragraph"
}
此片段程式碼可作為內容的單一認識點使用，因為只需此位於其中的資訊即可重新建立 HTML 代碼用於網站，並為其他媒體提供適當的格式。
支持的 Gutenberg 區塊
此外掛程式嘗試提取 WordPress 核心中所有附帶的 Gutenberg 區塊的 metadata；可以透過 hooks 增加其他區塊的支援，例如某些區塊只能應用於網站中，或者僅在基於屏幕的媒體上使用，等等。
目前未支援以下 WordPress 核心區塊：
外掛標籤
開發者團隊
原文外掛簡介
This plugin helps convert WordPress into a manager of our digital content, to publish it in different mediums or platforms: not just the website, but also email, iOS/Android apps, home-assistants (like Amazon Alexa) and others.
It does this by extracting the metadata from all Gutenberg blocks inside of a blog post. Because each Gutenberg block stores its own content and properties, these ones can be extracted as metadata and exported through a JSON object, accessible through a REST API endpoint, to feed any application on any platform.
The plugin makes the following REST API endpoints available:
/wp-json/block-metadata/v1/metadata/{POST_ID}: Extract all metadata from all Gutenberg blocks in a blog post with id {POST_ID}, converted to medium-agnostic (eg: removing all non-semantic HTML tags)
/wp-json/block-metadata/v1/data/{POST_ID}: Extract all data from all Gutenberg blocks in a blog post with id {POST_ID}, as originally stored in the block by Gutenberg (eg: containing HTML code)
Demonstration:
Blog post
Blog post’s Gutenberg blocks
Blog post’s medium-agnostic metadata
How does it work?
This plugin is based on the strategy called “Create Once, Publish Everywhere” (also called “COPE”), which reduces the amount of work needed to publish our content into different mediums by establishing a single source of truth for all content.
Having content that works everywhere is not a trivial task, since each medium will have its own requirements. For instance, whereas HTML is valid for printing content for the web, this language is not valid for an iOS/Android app; similarly, we can add classes to our HTML for the web, but these must be converted to styles for email.
The solution is to separate form from content: The presentation and the meaning of the content must be decoupled, and only the meaning is used as the single source of truth. The presentation can then be added in another layer, specific to the selected medium. For instance, given the following piece of HTML code, the
is an HTML tag which applies mostly for the web, and attribute class=”align-center” is presentation (placing an element “on the center” makes sense for a screen-based medium, but not for an audio-based one such as Amazon Alexa):
Hello world!
Hence, this piece of content cannot be used as a single source of truth, and it must be converted into a format which separates the meaning from the presentation, such as the following piece of JSON code:
{
content: "Hello world!",
placement: "center",
type: "paragraph"
}
This piece of code can be used as a single source of truth for content, since from it we can recreate once again the HTML code to use for the web, and procure an appropriate format for other mediums.
Supported Gutenberg blocks
This plugin attempts to extract the metadata for all Gutenberg blocks shipped in WordPress core; support for additional blocks, such as from plugins, can be added through hooks. Not all Gutenberg blocks can be supported (for instance, because they may only work for the web, or only make sense when applied to screen-based mediums, among other reasons).
The following WordPress core blocks are currently not supported:
"core/columns"
"core/column"
"core/cover"
"core/html"
"core/table"
"core/button"
"core/media-text"
The following Gutenberg blocks are supported, and this plugin extracts their metadata:
"core/paragraph"
"core/image"
"core-embed/youtube" (all other "core-embed" blocks can also be extracted, but must be implemented through a hook)
"core/heading"
"core/gallery"
"core/list"
"core/audio"
"core/file"
"core/video"
"core/code"
"core/preformatted"
"core/quote"
"core/pullquote"
"core/verse"
Extracting metadata for additional blocks
We can extend this plugin to extract the metadata for additional blocks, such as those shipped through plugins. To do this, simply add a hook for filter "Leoloso\BlockMetadata\Metadata::blockMeta" (located in function get_block_metadata($block_data) from class Metadata in file block-metadata/src/Metadata.php). The attributes that must be extracted must be decided on a block type by block type basis:
add_filter("Leoloso\BlockMetadata\Metadata::blockMeta", "extract_additional_block_metadata", 10, 3);
function extract_additional_block_metadata($blockMeta, $blockName, $block)
{
if ($blockName == "my-plugin/my-block-name") {
return array(
"property1" => $block["property1"],
"property2" => $block["property2"]
);
}
return $blockMeta;
}
Further references
Inspiration for the plugin
Slides from presentation “COPE with WordPress” (from WordCamp Singapore 2019), explaining how the plugin works
Contributing / Reporting issues
Please head over to the project’s GitHub repo for contributing, reporting issues or making suggestions, and others.
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