Ember-exex: Exceptional Exceptions for ambitious applications

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 | ____|_ __ ___ | |__   ___ _ __       _____  _______  __
 |  _| | '_ ` _ \| '_ \ / _ \ '__|____ / _ \ \/ / _ \ \/ /
 | |___| | | | | | |_) |  __/ | |_____|  __/>  <  __/>  < 
 |_____|_| |_| |_|_.__/ \___|_|        \___/_/\_\___/_/\_\
                                                               

Ember Exceptional Exceptions: Customizable error classes and error re-throwing with original error included

Why ember exex

When building advanced javascript application full featured error handling is required, but unfortunately it is not provided in javascript out of the box. Taste flavor of Java like exceptions in javascript:

• Custom error classes
• Re-throwing of an error with additional context and original error
• Additonal tooling

Console example

Compatiblity

Install

ember install ember-exex

Multiple error classes with inheritance

import {defineError} from 'ember-exex/error';

const ApplicationError = defineError({
    name: 'ApplicationError', 
    message: 'General application error'
});

const ServiceError = defineError({
    name: 'ServiceError', 
    message: 'Service error', 
    extends: ApplicationError
});

const UserInterfaceError = defineError({
    name: 'UserInterfaceError', 
    message: 'Service error', 
    extends: ApplicationError
});

try {
    throw new UserInterfaceError();
} catch (e) {

    console.log(e instanceof UserInterfaceError); // true
    console.log(e instanceof ApplicationError); // true
    console.log(e instanceof Error); // true
    console.log(e instanceof ServiceError); // false
    
    if (e instanceof UserInterfaceError) {
        resolveUserInterfaceError(e);
    } else if (e instanceof ServiceError) {
        resolveServiceError(e);
    } else if (e instanceof ApplicationError) {
        resolveGenericApplicationError(e);
    } else if (e instanceof Error) {
        resolveGenericError(e);
    }
}

Re-throwing error with wrapped catched error

import {defineError} from 'ember-exex/error';

const DatabaseError = defineError({
    name: 'DatabaseError', 
    message: 'Database error', 
    extends: ApplicationError
});
      
const UserInterfaceError = defineError({
    name: 'UserInterfaceError', 
    message: 'Service error', 
    extends: ApplicationError
});

try {
    throw new DatabaseError('Database IO error')
} catch (e) {
    throw new UserInterfaceError('Cannot render user interface')
        .withPreviousError(e);
}

Wrapped error is included as string in error.stack and stored as property on wrapping error error.previous

Parametrized error messages

import {defineError} from 'ember-exex/error';

const DatabaseError = defineError({
    name: 'DatabaseError', 
    message: "Database IO error at table '{table}' in '{db}'"
});

try {
    throw new DatabaseError({params: {db: 'mydb', table: 'posts'}});
} catch (e) {
    console.log(e.message); // Database IO error at 'posts' in 'mydb'
}

Extending errors

import {defineError} from 'ember-exex/error';

const ServiceError = defineError({
     name: 'ServiceError', 
     resolve: function() {
         GlobalExceptionManager.log(this);
     }
});

try {
    throw new ServiceError();
} catch (e) {
    if (e instanceof ServiceError) {
        e.resolve();
    } else {
        // do something else
    }
}