API: addActionInterceptor / removeActionInterceptor

Register (and unregister) global middleware functions that intercept chunk async actions. Useful for validation, logging, or performance tracking.

addActionInterceptor

function addActionInterceptor(
  interceptor: (
    ctx: ActionContext,
    next: () => any
  ) => any
): void

Registers an interceptor that will be called before every async action.

removeActionInterceptor

function removeActionInterceptor(
  interceptor: (
    ctx: ActionContext,
    next: () => any
  ) => any
): boolean

Removes a previously registered interceptor. Returns true if the interceptor was found and removed, false otherwise.

Tip: Keep a reference to the interceptor function so you can remove it later.

ActionContext Interface

interface ActionContext {
  /**
   * Name of the chunk (store) where the action is defined.
   */
  chunkName: string;

  /**
   * Name of the action or async action being executed.
   */
  actionName: string;

  /**
   * Arguments passed to the action.
   */
  args: any[];
}

Parameters

• interceptor: A function called before an action executes.

  • Receives a ctx object with chunkName, actionName, and args.
  • Must call next() to continue the chain and eventually run the action.
  • Can throw errors to halt execution or modify behavior.

Behavior

1. Registration: Call addActionInterceptor at app startup. Interceptors apply globally in registration order.
2. Removal: Call removeActionInterceptor with the same function reference to unregister it.
3. Interception: For each async action invocation, all registered interceptors run sequentially.
4. Chaining: Each interceptor calls next() to pass control to the next interceptor or final action.
5. Error Handling: Throwing inside an interceptor stops further interceptors and prevents the action from running.

Example

import { addActionInterceptor, removeActionInterceptor } from "mobx-chunk";

// Define the interceptor
const validateEmail = (ctx, next) => {
  if (ctx.actionName === "createUser") {
    const [payload] = ctx.args;
    if (!payload || typeof payload.email !== "string") {
      throw new Error(
        `[ValidationError] ${ctx.chunkName}.${ctx.actionName} expects { email: string }`
      );
    }
  }
  return next();
};

// Register
addActionInterceptor(validateEmail);

// Later, unregister when no longer needed
removeActionInterceptor(validateEmail);

Use addActionInterceptor to enforce data integrity, log user interactions, or measure performance across your mobx-chunk stores. Use removeActionInterceptor to clean up interceptors that are no longer needed.