#Context

In NocoBase, each request generates a ctx object, which is an instance of Context. Context encapsulates request and response information while providing NocoBase-specific functionality -- such as database access, cache operations, permission management, internationalization, and logging.

NocoBase's Application is based on Koa, so ctx is essentially a Koa Context, but NocoBase extends it with additional APIs, allowing you to conveniently handle business logic in Middleware and Actions. Each request has an independent ctx, ensuring data isolation between requests.

#ctx.action

ctx.action provides information about the Action being executed for the current request, including:

• ctx.action.params
• ctx.action.actionName
• ctx.action.resourceName

resourceManager.use(async (ctx) => {
  console.log(ctx.action.actionName); // Current Action name
  ctx.body = `Action: ${ctx.action.actionName}`;
});

#ctx.i18n & ctx.t()

Internationalization (i18n) support.

• ctx.i18n provides locale information
• ctx.t() is used to translate strings based on language

resourceManager.use(async (ctx) => {
  const msg = ctx.t('Hello World'); // Returns translation based on current language
  ctx.body = msg;
});

#ctx.db

ctx.db provides an interface for database access, allowing you to directly operate on models and execute queries.

resourceManager.use(async (ctx) => {
  const users = await ctx.db.getRepository('users').find();
  ctx.body = users;
});

#ctx.cache

ctx.cache provides cache operations, supporting reading from and writing to the cache, commonly used to accelerate data access or save temporary state.

resourceManager.use(async (ctx) => {
  await ctx.cache.set('key', 'value', { ttl: 60 }); // Cache for 60 seconds
  const val = await ctx.cache.get('key');
  ctx.body = val;
});

#ctx.app

ctx.app is the NocoBase application instance, allowing access to global configuration, plugins, and services.

resourceManager.use(async (ctx) => {
  console.log(ctx.app);
  ctx.body = 'Check console for app';
});

#ctx.auth.user

ctx.auth.user retrieves the currently authenticated user's information, suitable for use in permission checks or business logic.

resourceManager.use(async (ctx) => {
  if (!ctx.auth.user) {
    ctx.throw(401, 'Unauthorized');
  }
  ctx.body = `Hello ${ctx.auth.user.username}`;
});

#ctx.state.currentRoles

ctx.state is used to share data in the middleware chain.

resourceManager.use(async (ctx) => {
  ctx.body = `Current User: ${ctx.state.currentRoles.join(',')}`;
});

#ctx.logger

ctx.logger provides logging capabilities, supporting multi-level log output.

resourceManager.use(async (ctx) => {
  ctx.logger.info('Processing request for:', ctx.path);
  ctx.body = 'Logged successfully';
});

#ctx.permission & ctx.can()

ctx.permission is used for permission management, ctx.can() is used to check whether the current user has permission to execute a certain operation.

resourceManager.use(async (ctx) => {
  const canEdit = await ctx.can('edit', 'posts');
  if (!canEdit) {
    ctx.throw(403, 'Forbidden');
  }
  ctx.body = 'You have permission to edit posts';
});

#Summary

• Each request corresponds to an independent ctx object
• ctx is an extension of Koa Context, integrating NocoBase functionality
• Common properties include: ctx.db, ctx.cache, ctx.auth, ctx.state, ctx.logger, ctx.can(), ctx.t(), etc.
• Using ctx in Middleware and Actions allows for convenient handling of requests, responses, permissions, logs, and the database

#Related Links

• Middleware — Full workflow of using ctx to handle requests in middleware
• ResourceManager — Source and definition of ctx.action in resource Actions
• ACL — Permission checking mechanism for ctx.permission and ctx.can()
• Cache — Detailed usage of ctx.cache for cache operations
• Logger — Logging and output configuration for ctx.logger
• i18n — Internationalization support for ctx.t() and ctx.i18n