Block Protocol – Graph module

This package implements the Block Protocol Graph module for blocks and embedding applications.

Getting started

If you are a block author, we have several block templates available which use this package

npx create-block-app@latest --help

The best way to get started is to read the docs.

stdlib

The package exports a standard library of helper functions for interacting with a Subgraph, available from "@blockprotocol/graph/stdlib". For example

import { getOutgoingLinkAndTargetEntities } from "@blockprotocol/graph/stdlib";

// find the outgoing links and target entities for a given entity
const linkAndTargetEntities = getOutgoingLinkAndTargetEntities(
  subgraph,
  "entity-123",
);

for (const { linkEntity, rightEntity } of linkAndTargetEntities) {
  // do something with each link and the entity it points to
}

For a full list of available functions see src/stdlib.ts

Initializing a graph module handler

If you want to roll your own block template or embedding application, you can use this package to construct a handler for graph module messages.

1. yarn add @blockprotocol/graph or npm install @blockprotocol/graph
2. Follow the instructions to use the graph module as a block or an embedding application

Blocks

To create a GraphBlockHandler, pass the constructor an element in your block, along with any callbacks you wish to register to handle incoming messages.

React

For React, we provide a useGraphBlockModule hook, which accepts a ref to an element, and optionally any callbacks you wish to provide on initialization.

See npx create-block-app@latest my-block --template react for an example.

Custom elements

For custom elements, this package exports a BlockElementBase class which uses the Lit framework, and sets graphModule on the instance for sending graph-related messages to the embedding application.

See npx create-block-app@latest my-block --template custom-element for an example.

Embedding applications

You should construct one GraphEmbedderHandler per block.

It is not currently possible to wrap multiple blocks with a single handler.

To create a GraphEmbedderHandler, pass the constructor:

1. An element wrapping your block
2. callbacks to respond to messages from the block
3. The starting values for the following messages:

• blockEntitySubgraph: the graph rooted at the block entity
• readonly: whether or not the block should be in 'readonly' mode

These starting values should also be passed in a graph property object, if the block can be passed or assigned properties.

See the here or check the TypeScript types for message signatures.

import { GraphEmbedderHandler } from "@blockprotocol/graph";

const graphModule = new GraphEmbedderHandler({
  blockEntitySubgraph: { ... }, // subgraph containing vertices, edges, and 'roots' which should be a reference to the block entity
  readonly: false,
  callbacks: {
    updateEntity: ({ data }) => updateEntityInYourDatastore(data),
  },
  element: elementWrappingTheBlock,
});

React

For React embedding applications, we provide a useGraphEmbedderModule hook, which accepts a ref to an element, and optionally any additional constructor arguments you wish to pass.

import { useGraphEmbedderModule } from "@blockprotocol/graph";
import { useRef } from "react";

export const App = () => {
  const wrappingRef = useRef<HTMLDivElement>(null);

  const blockEntitySubgraph = { ... }; // subgraph containing vertices, edges, and 'roots' which should be a reference to the block entity

  const { graphModule } = useGraphEmbedderModule(blockRef, {
    blockEntitySubgraph,
  });

  return (
    <div ref={wrappingRef}>
      <Block graph={{ blockEntitySubgraph }} />
    </div>
  );
};