---
title: 🟠 High  Order Operator Bug
description: Challenge 11 is about resolving a Rxjs bug because of high order operators
sidebar:
  order: 11
---

:::note
WIP: The following documentation will be reviewed and improved. However, you can still take on the challenge. If you don't understand a certain part, please feel free to reach out or create an issue.
:::

<div class="chip">Challenge #11</div>

Let's dive inside the wonderful word of RxJs.

This challenge is inspired by a real-life example.

## Presentation of the challenge

### User Story

We need a button for each `Topic`. When we click on it, we delete all objects with this `Topic` in our database _(Fake DB in our case)_. Finally we display **All [topic] have been deleted** is everything was deleted successfully or **Error: deletion of some [topic] failed** if some deletions failed

### Constraints:

We can only pass one object to our DB for deletion at the time. The DB will respond true if the data was successfully deleted and false otherwise.

### What you need to do

The QA team reports a **bug**. The UI shows **All [topic] have been deleted** all the time, even if some deletions fail.

👉 Spot the bug and correct it.

---

:::note
Start the project by running: `npx nx serve rxjs-pipe-bug`.
:::

:::tip[Reminder]
Your PR title must start with <b>Answer:11</b>.
:::

<div class="article-footer">
  <a
    href="https://github.com/tomalaforge/angular-challenges/pulls?q=label%3A11+label%3Aanswer"
    alt="High  Order Operator Bug community solutions">
    ❖ Community Answers
  </a>
  <a
    href='https://github.com/tomalaforge/angular-challenges/pulls?q=label%3A11+label%3A'
    alt="High  Order Operator Bug solution author">
    ▶︎ Author Answer
  </a>
  </div>
