πŸ’¬ Proposing a new approach for 'Gutenberg and Decoupled Applications'

β€” 21 minute read

A few days ago, WPGraphQL's creator Jason Bahl published Gutenberg and Decoupled Applications, analyzing the benefits and shortcomings of 3 approaches to integrating GraphQL with Gutenberg.

A week earlier, he had also said on Twitter that the GraphQL API for WordPress's approach to modeling Gutenberg is inappropriate:

This isn’t something to brag about, in my opinion. One thing GraphQL tries to solve with a Typed Schema is providing predictability and consistency for clients, and giving clients control to ask for what they want, down to the field.

Returning a wildcard β€œObject” Type with no predictable shape means client applications can break at any time because there’s no longer a contract between the Server and the client. The server now has taken away control from the client.

Through this article, I join the conversation. I'll address Jason's criticism and, in doing so, describe my plugin's approach, and show why I believe it can actually suit Gutenberg very well.

Using COPE to extract Gutenberg metadata permalink

My solution could be considered the 4th approach, and it's the following:

To obtain the Gutenberg data to power GraphQL, do not create an additional schema on the PHP side, or duplicate any existing data. Instead, extract the data from the blocks' stored content, using the COPE ("Create Once, Publish Everywhere") strategy.

(COPE is a strategy that enables to have a single source of truth of content, and expose it to different applications. In our case, the single source of truth is the Gutenberg block data, as it is stored in the database. I have described COPE, and its implementation for WordPress, in this article.)

Finally, we can use GraphQL to retrieve the extracted data, for any Gutenberg block, by mapping all blocks to a single Block type.

This strategy is a trade-off, not a definitive solution permalink

This strategy does not solve the issue that Jason is pointing out: the lack of a schema on the server-side, which would enable the creation of a contract between the server and the client.

COPE can't solve this issue because, solely from the stored content, we can't recreate the schema:

  • The stored content does not indicate the type of the field
  • The stored content does not indicate what restrictions the field has (is it nullable? is it a positive integer? is the string for an email or an URL?)
  • Nullable fields can have a default value, which won't be present on the stored content

However, using the COPE strategy, and a single Block type to represent all blocks, the GraphQL API plugin can build a very decent integration with Gutenberg, that overcomes the existing limitations.

I'll explain throughout this article.

GraphQL API's integration with Gutenberg permalink

This solution is a work in progress, but I can already explain how it will behave.

Instead of depending on a different type per block (as WPGraphQL does when relying on the WPGraphQL for Gutenberg plugin), the GraphQL API plugin will provide a single Block type to represent all blocks.

In this query, the field Post.blockMetadata retrieves a list of Block elements from the post (for different Gutenberg blocks, including paragraphs, images, lists, and others). Press on the "Run" button on the client below, to execute the query:

If we want to retrieve data for a specific block, we can filter based on the block's name (core/paragraph, core/quote, etc).

In this query, we only retrieve the image blocks:

Inspecting the single Block type permalink

With this approach, the response can vary depending on the stored content, not on a schema. This quality is both its advantage (since it makes the API flexible) and its disadvantage (we can't enforce server-client contracts).

Every Block element contains two properties:

  • name: The name of the block (core/paragraph, core/quote, etc)
  • meta: The metadata contained in the block

Every Gutenberg block is different, containing different data (a paragraph content, a Youtube video, an image source URL and dimensions, etc). Hence, the data contained in the response for the meta field will also be different.

As such, the meta field has been mapped simply as a JSON object (which can contain "raw" data), via a corresponding JSONObject type in the GraphQL schema.

It produces this response:

{
"data": {
"post": {
"title": "COPE with WordPress: Post demo containing plenty of blocks",
"blockMetadata": [
{
"blockName": "core/paragraph",
"meta": {
"content": "Lorem ipsum dolor sit amet"
}
},
{
"blockName": "core/image",
"meta": {
"src": "https://ps.w.org/gutenberg/assets/banner-1544x500.jpg"
}
},
{
"blockName": "core/quote",
"meta": {
"quote": "Etiam tempor orci eu lobortis elementum nibh tellus molestie",
"cite": "Aristoteles"
}
},
{
"blockName": "core/heading",
"meta": {
"size": "xl",
"heading": "Welcome to my site"
}
},
{
"blockName": "core/list",
"meta": {
"items": [
"First element",
"Second element",
"Third element"
]
}
},
]
}
}
}

As we can see, we have different blocks retrieving different properties:

  • core/paragraph has property content
  • core/image has property src, and optionally properties width, height and caption (not appearing in the response above)
  • core/quote has properties quote and cite (for the quoted person)
  • core/heading has properties header and size (value xl represents <h2>, because COPE decouples the value from the target application, in this case a website)
  • core/list has property items, which is a list of elements

Why the JSONObject type is not part of the spec permalink

The JSONObject type I described above allows GraphQL to retrieve "dynamic" fields (such as fields that we don't know of), or fields which can have multiple configurations (as may be the case with Gutenberg blocks).

Now, the GraphQL spec currently does not support the JSONObject or Map types. Adding support has been requested, for reasons such as:

[...] the lack of this feature is particularly problematic because it's supported in many of the type systems and services that GraphQL interfaces with.

This leads to implementing custom resolvers on the server, followed by custom transforms on the client, to deal with situations where my server is sending a Map, and my client wants a Map, and GraphQL is in the middle with no support for Maps. Yes, it is possible, and I have done it, but it is fair bit of boilerplate and abstraction that seems to defeat the purpose of writing the API spec in GraphQL.

This feature is not supported by the spec because dealing with dynamic fields goes against GraphQL's strong typing behavior, which breaks the contract between the server and the client.

Still, this type can be benefitial to Gutenberg, as I will show later on.

Problems when using a different type per block, and a server-side registry permalink

If creating a new GraphQL type per block, then all plugins must have their blocks be added to the GraphQL schema. This could be automatically accomplished by having all blocks define their properties on the proposed new server-side registry.

If they don't, their blocks will be unavailable to the API, and this can have additional consequences. In some circumstances, the whole queried post's content may become unreliable.

This may be the case when GraphQL interacts with an external cloud-based service, which applies some function to all the blocks in the post (think of translation, fixing grammar, SEO suggestions, analytics, etc).

Let's see an example of this.

Since multilingual capabilities will be added to Gutenberg in phase 4, let's model how to translate all blocks in the plugin, via a call to the Google Translate API executed via a @translate directive.

(After this initial API-based translation, the user can keep editing the blog post, in the translated language, always within the WordPress editor.)

Different blocks contain different pieces of information that must be translated:

  • core/paragraph: the text
  • core/image: the caption
  • core/quote: the quote, and the quoted person (since it could be the person's title, such as "The school headmaster")
  • core/heading: the header
  • core/list: all the items in the list

Using a different type per block, the resulting query may be something like this:

{
post(id: 1) {
blocks {
... on CoreParagraphBlock {
content @translate
}
... on CoreImageBlock {
caption @translate
}
... on CoreQuoteBlock {
quote @translate
cite @translate
}
... on CoreHeadingBlock {
heading @translate
}
... on CoreListBlock {
items @translateList
}
... on EmbedTwitterBlock {
caption @translate
}
... on EmbedYoutubeBlock {
caption @translate
}
... on EmbedVimeoBlock {
caption @translate
}
}
}
}

And so on and on. The more blocks we have, the longer this query will be, easily spanning a hundred lines and even more.

The obvious problem is that the query becomes a wild beast that we need to maintain.

Also, we need to introduce custom functionality to make it work for every block. For instance, @translate doesn't work with CoreListBlock.items, which returns a list of strings (i.e. it returns [String], while the directive expects String), and so we have to create @translateList.

And then core/table would need its own custom directive (@translateTable?).

And custom 3rd-party blocks may need their own custom directives.

And then, I see a couple more issues.

It's all or nothing permalink

A blog post may contain any block installed in the WordPress editor. And we don't know in advance (when coding the query) what blocks does the post consume.

Then, at one type per block, the number of types to handle in the query will not be equivalent to the number of blocks in the post. Instead, it will be equivalent to the number of blocks installed in the WordPress editor.

What happens if we have 100 blocks on our site, including both from WordPress core and plugins? Then we need to have 100 types mapped to the GraphQL schema. A single one that is not mapped can break the "content contract", resulting in some blocks being translated from English to French, while others remain in English.

As a result, we won't be able to trust the translated posts anymore, whether they contain the offending block or not. So if not all blocks are added to the registry, then the application may become unreliable.

The query must be updated every time a new block is installed permalink

Likewise, every block must be handled on the GraphQL query. That means that, whenever installing a new block, we need to go to our application's code, update it, and re-deploy it.

This is not just extra bureaucracy: We won't be able to install a block on a live site, without the fear of breaking the application (until all queries are updated).

GraphQL must serve WordPress, not the other way around permalink

Considering again why the JSONObject was not added to the GraphQL spec, it is because it doesn't suit the GraphQL way of doing things.

However, here we are not truly concerned with GraphQL. We only care about WordPress and, more specifically in this case, Gutenberg.

When integrating GraphQL with Gutenberg, GraphQL will operate within the context of WordPress. That means that WordPress will need to satisfy the requirements from GraphQL. But more importantly, it is GraphQL that needs to satisfy the requirements from WordPress.

And in case of conflict, WordPress has priority.

If a feature does not suit GraphQL, but it nevertheless suits Gutenberg, should it considered?

I think it should.

Let's see how a single Block type can better serve Gutenberg.

Solving the previous problems via a single Block type permalink

Following the previous example, translating all the blocks in a post from English to French, using a single Block type, will be done like this (or something around this concept):

{
post(id:1) {
blocks {
name
meta
@advancePointersInArray(paths: "{{ translatablePaths }}")
@forEach(nestedUnder: -1)
@translate(from: "en", to: "fr", nestedUnder: -1)
}
}
}

That's it? The whole query? To translate all blocks? Yes.

Will it work for all blocks, from both core and plugins, already existing or yet-to-be-created? Yes.

Does this query look a bit strange to you? If it does, it's because it uses non-standard GraphQL features, supported only by the GraphQL API plugin:

  • {{ translatablePaths }} is an embeddable field, to input the value of a field as argument to another field or directive (in this case, the Block type will have a field translatableFields, whose value is injected to directive @advancePointersInArray)
  • directives can be composed by other directives (by the one indicated through param nestedUnder)

Now, if a feature satisfies exactly what the CMS needs, but the feature is non-standard, should we still use it? I think we should.

I have also requested these features for the GraphQL spec (even though, they will not be accepted):

How the single Block type works permalink

Warning: technical section ahead.

The Block type will have a field translatablePaths, returning an array of the properties from the JSONObject that must be translated:

  • core/paragraph returns ["content"]
  • core/image returns ["caption"]
  • core/quote returns ["quote", "cite"]
  • core/heading returns ["header"]
  • core/list returns ["items.0", "items.1", "items.2", ...]

@advancePointersInArray is a meta-directive: it modifies the context for a subsequent directive. It makes the subsequent directive receive a sub-element from within the queried JSONObject, such as the content property from the paragraph block. The list of paths is obtained via field translatablePaths, evaluated on the same queried entity.

Then, @forEach is another meta-directive, which iterates over a list of elements from the queried entity, and passes a reference to the iterated element to the next directive. In this case, it gets all the list of the properties to translate for all entities, each of them of type String, and passes individual String elements down the line.

Finally, directive @translate receives an element of type String contained within the JSONObject, and it translates it right there, within the JSONObject itself.

Please notice how flexible this solution is. Just providing the path to the string within the JSONObject is enough to access the value, modify it with @translate (or any other directive), and possibly even store the value again on the DB (work to accomplish this is currently in progress).

It already works for core/list, since all the elements in the list can be reached under their own path (items.0 is the 1st element in the array, and so on). Then, it can access the String value from each, and pass it down to @translate, so there is no need to create @translateList.

Similarly, it will also work with core/table. We just need to expose the data via property cells, which will be an array of 2 dimensions (one for rows, containing one for columns). Then, translatablePaths can reach all elements as ["cells.0.0", "cells.0.1", "cells.1.0", ...].

And it will work for any 3rd-party block too. For that, we must pay attention how the block data is stored, and from there we can deduce the path to its properties.

A single Block requires configuration, based on PHP code permalink

Mapping the blocks, so that we know where to find their metadata properties, can be accomplished through configuration. So we can deal with it in a very flexible way.

In Gutenberg, there are two places where a property from the block can be stored: as an attribute, or inside the rendered content.

For instance, this is how the core/image block is stored:

<!-- wp:image {"id":1670,"sizeSlug":"large","linkDestination":"none"} -->
<figure class="wp-block-image size-large">
<img src="https://newapi.getpop.org/wp/wp-content/uploads/2021/01/dynamic-include-first-query.png" alt="" class="wp-image-1670"/>
</figure>
<!-- /wp:image -->

In this case, we have:

  1. Properties id, sizeSlug and linkDestination are stored as attributes
  2. Property src is stored inside the rendered content

Now, when querying the API, the response for the core/image block will be the following:

{
"data": {
"blocks": [
{
"name": "core/image",
"meta": {
"id": 1670,
"sizeSlug": "large",
"linkDestination": "none",
"src": "https://newapi.getpop.org/wp/wp-content/uploads/2021/01/dynamic-include-first-query.png"
}
}
]
}
}

The API knows how to retrieve the properties by parsing the stored block in Gutenberg (that is the COPE strategy). This process can be done automatically up to some degree, and then some manual input via hooks, or through some user interface.

To obtain the properties directly mapped as attributes is trivial. The GraphQL server can already retrieve all attributes from the block, and make them available as properties. Or, if we want to explicitly define which ones to expose, we can do it via filter hooks:

$attrs = apply_filters("blockPropsAsAttr:core/image", []);

add_filter("blockPropsAsAttr:core/image", function ($attrs) {
return array_merge($attrs, ['id', 'sizeSlug', 'linkDestination']);
})

The properties stored in the content can be extracted via some regex:

$propRegexes = apply_filters("blockPropsAsRegex:core/image", []);

add_filter("blockPropsAsRegex:core/image", function ($propRegexes) {
$propRegexes['src'] = '/<img src="(.*?)"/';
return $propRegexes;
})

Finally, we indicate which are the block's translatable properties, for @translate to act upon:

$propRegexes = apply_filters("translatableProperties:core/image", []);

add_filter("translatableProperties:core/image", function ($properties) {
$properties[] = 'caption';
return $properties;
})

Now, these properties must still be satisfied by somebody, most likely the plugin developer. Hence, having the server-side registry will help achieve this goal.

But what if the WordPress community does not want to add the proposed server-side registry? Well, this strategy can easily adapt, because the mapping can be done via PHP code, as just shown.

If any block has not been mapped, the user can also do it, just knowing a bit about Gutenberg, and nothing about GraphQL or schemas.

In addition, we can have GraphQL alert the user when there is block that has not been mapped (and so it can't be translated). We can do this by adding an @if meta-directive which, if the condition applies, executes the @sendEmail directive:

{
post(id:1) {
blocks {
name
meta
@advancePointersInArray(paths: "{{ translatablePaths }}")
@forEach(nestedUnder: -1)
@translate(from: "en", to: "fr", nestedUnder: -1)
@if(condition: "{{ isTranslatablePathsUnmapped }}")
@sendEmail(
to: "{{ root.adminEmail }}",
subject: "Block with name {{ name }} has 'translatablePaths' unmapped",
nestedUnder: -1
)
}
}
}

This solution is flexible and simple, and has GraphQL serving WordPress, without requiring developers to learn a new technology, or changing how Gutenberg works.

Conclusion permalink

When thinking of how a possible integration between GraphQL and Gutenberg will look like (from a potential inclusion in WordPress core), we must make sure that GraphQL can handle all the future requirements by Gutenberg, including full support for:

  • multilingual blocks
  • Full Site Editing
  • collaborative editing
  • interacting with 3rd-party services on a live site

All of this must be accomplished hopefully without needing to change Gutenberg (at least, not in a considerable way), and reducing the new tasks required from plugin developers.

Taking these into account, I believe that the 4th approach I'm here suggesting can indeed work very well.

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