#Building a Custom Display Block

In NocoBase, blocks are content areas on a page. This example demonstrates how to build the simplest custom block using BlockModel -- supporting HTML content editing through the UI, allowing users to modify the block's displayed content via a configuration panel.

This is the first example involving FlowEngine, using BlockModel, renderComponent, registerFlow, and uiSchema.

#Final Result

We're building a "Simple block":

• Appears in the "Add Block" menu
• Renders user-configured HTML content
• Allows users to edit HTML through a configuration panel (registerFlow + uiSchema)

Full source code is available at @nocobase-example/plugin-simple-block. If you want to run it locally:

yarn pm enable @nocobase-example/plugin-simple-block

Let's build this plugin step by step from scratch.

#Step 1: Create the Plugin Skeleton

Run the following in the repository root:

yarn pm create @my-project/plugin-simple-block

This will generate a basic file structure under packages/plugins/@my-project/plugin-simple-block. For detailed instructions, see Writing Your First Plugin.

#Step 2: Create the Block Model

Create src/client-v2/models/SimpleBlockModel.tsx. This is the core of the entire plugin -- defining how the block renders and how it's configured.

// src/client-v2/models/SimpleBlockModel.tsx
import React from 'react';
import { BlockModel } from '@nocobase/client-v2';
import { tExpr } from '../locale';

export class SimpleBlockModel extends BlockModel {
  renderComponent() {
    return <div dangerouslySetInnerHTML={{ __html: this.props.html }} />;
  }
}

// Set the display name in the "Add Block" menu
SimpleBlockModel.define({
  label: tExpr('Simple block'),
});

// Register a configuration panel to let users edit HTML content
SimpleBlockModel.registerFlow({
  key: 'flow1',
  title: tExpr('Simple Block Flow'),
  on: 'beforeRender', // Execute before rendering
  steps: {
    editHtml: {
      title: tExpr('Edit HTML Content'),
      // uiSchema defines the form UI of the configuration panel
      uiSchema: {
        html: {
          type: 'string',
          title: tExpr('HTML Content'),
          'x-decorator': 'FormItem',
          'x-component': 'Input.TextArea',
        },
      },
      // Default values for the configuration panel
      defaultParams: {
        html: `<h3>This is a simple block</h3>
<p>You can edit the HTML content.</p>`,
      },
      // Write configuration panel values to model's props
      handler(ctx, params) {
        ctx.model.props.html = params.html;
      },
    },
  },
});

Key points:

• renderComponent() -- Renders the block UI, reading HTML content via this.props.html
• define() -- Sets the display name in the "Add Block" menu. tExpr() is used for deferred translation because define() executes at module load time, when i18n hasn't been initialized yet
• registerFlow() -- Adds a configuration panel. uiSchema defines the form using JSON Schema (syntax reference: UI Schema), handler writes user-filled values to ctx.model.props, and renderComponent() can read them

#Step 3: Add Multilingual Files

Edit the translation files under the plugin's src/locale/, adding translations for all keys used by tExpr():

// src/locale/zh-CN.json
{
  "Simple block": "简单区块",
  "Simple Block Flow": "简单区块配置",
  "Edit HTML Content": "编辑 HTML 内容",
  "HTML Content": "HTML 内容"
}

// src/locale/en-US.json
{
  "Simple block": "Simple block",
  "Simple Block Flow": "Simple Block Flow",
  "Edit HTML Content": "Edit HTML Content",
  "HTML Content": "HTML Content"
}

For more about translation file conventions and tExpr() usage, see i18n Internationalization.

#Step 4: Register in the Plugin

Edit src/client-v2/plugin.tsx to lazy-load the model via registerModelLoaders:

// src/client-v2/plugin.tsx
import { Plugin } from '@nocobase/client-v2';

export class PluginSimpleBlockClient extends Plugin {
  async load() {
    this.flowEngine.registerModelLoaders({
      SimpleBlockModel: {
        // Lazy loading -- the module is only loaded when first used
        loader: () => import('./models/SimpleBlockModel'),
      },
    });
  }
}

export default PluginSimpleBlockClient;

registerModelLoaders uses dynamic imports so that model code is only loaded when actually needed -- this is the recommended registration approach.

#Step 5: Enable the Plugin

yarn pm enable @my-project/plugin-simple-block

After enabling, create a new page and click "Add Block" to see "Simple block". Once added, click the block's configuration button to edit the HTML content.

#Full Source Code

• @nocobase-example/plugin-simple-block -- Complete custom display block example

#Summary

Capabilities used in this example:

#Related Links

• Writing Your First Plugin -- Create a plugin skeleton from scratch
• FlowEngine Overview -- FlowModel basic usage and registerFlow
• FlowEngine -> Block Extension -- BlockModel, DataBlockModel, CollectionBlockModel
• UI Schema -- uiSchema syntax reference
• Component vs FlowModel -- When to use FlowModel
• Plugin -- Plugin entry point and load() lifecycle
• i18n Internationalization -- Translation file conventions and tExpr usage
• FlowEngine Complete Documentation -- Complete reference for FlowModel, Flow, Context