elledienne

# Instructions for Using Zero Custom Mutators

## Overview

Zero Custom Mutators provide a powerful mechanism for defining data write operations beyond simple CRUD. They allow you to embed arbitrary code within your write logic, running both client-side for optimistic updates and server-side for authority and complex operations.

**Key Concepts:**

- **Arbitrary Code:** Mutators are functions, enabling complex validation, permissions, calling external services (like LLMs or sending emails), calling queue, etc.
- **Client-Side Execution:** Mutators run immediately on the client for instant UI feedback.

elledienne

# To be placed inside .github/actions like .github/actions/cleanup-pr/action.yml

name: "Cleanup PR Database Resources"
description: "Cleanup database resources for a specific PR"

inputs:
  pr_number:
    description: "PR number to cleanup"
    required: true
  pg_cluster_url:

elledienne

version: "3.3"

services:
  charts:
    image: quay.io/mongodb/charts:v0.10.0
    hostname: charts
    ports:
      # host:container port mapping. If you want MongoDB Charts to be
      # reachable on a different port on the docker host, change this
      # to <port>:80, e.g. 8888:80.

elledienne

// Remember to overwite the code in CodeShare, JSFiddle, etc. to restore the inital state of the test and to avoid
// showing to candidates the changes made during other interwies

// TASKS:
// 1. Ask to developer to analyze the above React component:
//    - The dev should be able read, understand and explain the component
//    - The dev should be able to explain why it's necessary to .bind the method .addItem (and what other option we have: arrow function)
//    - The dev should be able to understand that it's a functional component
//    - The dev should be able to describe the behaviour of the component without rendering it

elledienne

// Remember to overwite the code in CodeShare, JSFiddle, etc. to restore the inital state of the test and to avoid
// showing to candidates the changes made during other interwies

// TASKS:
// 1. Ask to developer to analyze the provide (broken) snippet:
//    - The dev should be able to understand the intent of the snipped
//    - The dev should be able to predict the (unexpected) behaviour
//    - The dev should be able to provide at least one fix (and discuss about it)

const initialValues = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];

elledienne

// Remember to overwite the code in CodeShare, JSFiddle, etc. to restore the inital state of the test and to avoid
// showing to candidates the changes made during other interwies

// TASKS:
// 1. Ask to developer to write a foreach function:
//    - The dev should be familiar with .forEach/.each()
//    - The dev should be familiar with the interface of these methods
//    - The dev should be able to implement it (quite easy, see below for the implementation)
// 2. Ask to developer to write a map function:
//    - The dev should be familiar with .map()

elledienne

// Remember to overwite the code in CodeShare, JSFiddle, etc. to restore the inital state of the test and to avoid
// showing to candidates the changes made during other interwies

// TASKS:
// 1. Ask to developer to go through the file and analyze it. The dev should:
//    - Notice that the first comment return "undefined"
//    - Notice that the second comment return "of Barcelona's weather"
//    - Talk about hoisting
//    - Identify what would happen if we would use "let" instead of "var" (ReferenceError: testVar is not defined)

elledienne

// Remember to overwite the code in CodeShare, JSFiddle, etc. to restore the inital state of the test and to avoid
// showing to candidates the changes made during other interwies

// TASKS:
// 1. Ask to developer to go through the file and analyze it. The dev should notice:
//    - Constructor (at this point we can talk also about classes in ES6
//    - Destructuring
//    - String interpolation
//    - Context (and should notice (and fix) that the callback passed to the onclick will log "I'm a button and I undefined" because it's not bound to
//      the context ('dog')