Following tryCatch decorator is unable to catch the error.

const TryCatchWrapper = (target, key, descriptor) => {
  const fn = descriptor.value;
  descriptor.value = (...args) => {
    try {
      fn.apply(this, args);
    } catch (error) {
      console.log('Entered Catch----->');
      const [,, next] = args;
      next(error);
    }
  };
};

Trying to use in the following class-

class CustomerDetails {

  @TryCatchWrapper
  async getCustomerSummary(req, res, next) {
      throw new Error('Whoops!!!');
  }
}

Problem:- 'Entered Catch----->' never gets printed.

Following tryCatch decorator is unable to catch the error.

const TryCatchWrapper = (target, key, descriptor) => {
  const fn = descriptor.value;
  descriptor.value = (...args) => {
    try {
      fn.apply(this, args);
    } catch (error) {
      console.log('Entered Catch----->');
      const [,, next] = args;
      next(error);
    }
  };
};

Trying to use in the following class-

class CustomerDetails {

  @TryCatchWrapper
  async getCustomerSummary(req, res, next) {
      throw new Error('Whoops!!!');
  }
}

Problem:- 'Entered Catch----->' never gets printed.

• javascript
• jquery
• node.js

• Did you ever get this working? – jackdaw Commented Jul 30, 2018 at 13:55

2 Answers 2

It's because getCustomerSummary is an async function. An async function never throws; instead, it returns a promise that gets rejected. (Inside an async function, when you use try/catch around await, that gets turned into promise rejection handling. But in a non-async function calling an async function, that sugar isn't applied.)

You'll need to modify the decorator to look at the return value of the function and, if it's a promise, handle promise rejections.

Actually there is nothing wrong with your approach. You just forgot to await for results from fn.apply and set the descriptor.value as async function. See the example here https://stackblitz./edit/typescript-dycwcg

const TryCatchWrapper = (target, key, descriptor) => {
  const fn = descriptor.value;
  descriptor.value = async (...args) => {
    try {
      await fn.apply(this, args);
    } catch (error) {
      console.log('Entered Catch----->');
      const [,, next] = args;
      next(error);
    }
  };
};