umbraco-context-api（umbraco context API 文档）

Umbraco Context API

What is it?

The Context API is Umbraco's communication system that enables extensions to share data and functionality through the component hierarchy without tight coupling. It uses a provider-consumer pattern where parent elements provide contexts that descendant components can access. Contexts cascade down through the DOM tree and use tokens for type-safe access to services like notifications, workspaces, and user information.

Documentation

Always fetch the latest docs before implementing:

• Main docs: https://docs.umbraco.com/umbraco-cms/customizing/foundation/context-api
• Consume Context: https://docs.umbraco.com/umbraco-cms/customizing/foundation/context-api/consume-a-context
• Provide Context: https://docs.umbraco.com/umbraco-cms/customizing/foundation/context-api/provide-a-context
• Foundation: https://docs.umbraco.com/umbraco-cms/customizing/foundation

Workflow

1. Fetch docs - Use WebFetch on the URLs above
2. Ask questions - Need to consume or provide? Which context? One-time or subscription?
3. Generate code - Implement context consumption or provision based on latest docs
4. Explain - Show what was created and how contexts flow

Minimal Examples

Consuming Context (Subscription Pattern)

import { UmbLitElement } from '@umbraco-cms/backoffice/lit-element';
import { UMB_NOTIFICATION_CONTEXT } from '@umbraco-cms/backoffice/notification';

export class MyElement extends UmbLitElement {
  #notificationContext?: typeof UMB_NOTIFICATION_CONTEXT.TYPE;

  constructor() {
    super();

    // Subscribe to context - callback runs when context is available
    this.consumeContext(UMB_NOTIFICATION_CONTEXT, (context) => {
      this.#notificationContext = context;
    });
  }

  showMessage() {
    this.#notificationContext?.peek('positive', {
      data: { message: 'Hello from Context API!' }
    });
  }
}

Consuming Context (One-time Pattern)

import { UmbControllerBase } from '@umbraco-cms/backoffice/class-api';
import { UMB_NOTIFICATION_CONTEXT } from '@umbraco-cms/backoffice/notification';

export class MyService extends UmbControllerBase {
  async showNotification(text: string) {
    // Get context once, use it, then release
    const context = await this.getContext(UMB_NOTIFICATION_CONTEXT);
    context?.peek('positive', { data: { message: text } });
  }
}

Providing Context

import { UmbLitElement } from '@umbraco-cms/backoffice/lit-element';
import { UmbContextToken } from '@umbraco-cms/backoffice/context-api';

// Define a context token
export const MY_CUSTOM_CONTEXT = new UmbContextToken<MyCustomContext>(
  'MyCustomContext'
);

export class MyCustomContext {
  getData() {
    return { message: 'Hello from custom context!' };
  }
}

export class MyProviderElement extends UmbLitElement {
  constructor() {
    super();

    // Provide context to all descendants
    this.provideContext(MY_CUSTOM_CONTEXT, new MyCustomContext());
  }
}

Common Built-in Contexts

// Notifications
import { UMB_NOTIFICATION_CONTEXT } from '@umbraco-cms/backoffice/notification';

// Current User
import { UMB_CURRENT_USER_CONTEXT } from '@umbraco-cms/backoffice/current-user';

// Modal Manager
import { UMB_MODAL_MANAGER_CONTEXT } from '@umbraco-cms/backoffice/modal';

// Workspace (varies by type)
import { UMB_DOCUMENT_WORKSPACE_CONTEXT } from '@umbraco-cms/backoffice/document';

// Block Entry (for block editors)
import { UMB_BLOCK_ENTRY_CONTEXT } from '@umbraco-cms/backoffice/block';

// Property Dataset (for property editors)
import { UMB_PROPERTY_DATASET_CONTEXT } from '@umbraco-cms/backoffice/property';

Key Concepts

Context Token: Type-safe identifier for a context

const MY_TOKEN = new UmbContextToken<MyType>('UniqueName');

Provider: Element that provides context to descendants via provideContext()

Consumer: Element that accesses context via consumeContext() or getContext()

Subscription vs One-time:

• Use consumeContext() when you need the context during initialization
• Use getContext() for actions triggered by user interaction

Hierarchy: Contexts flow DOWN the DOM tree from provider to consumers

That's it! Always fetch fresh docs, keep examples minimal, generate complete working code.