freeCodeCamp/curriculum/challenges/english/05-apis-and-microservices/mongodb-and-mongoose/chain-search-query-helpers-to-narrow-search-results.md

---
id: 587d7fb9367417b2b2512c12
title: Chain Search Query Helpers to Narrow Search Results
challengeType: 2
forumTopicId: 301533
---

## Description

<section id='description'>

If you don’t pass the callback as the last argument to `Model.find()` (or to the other search methods), the query is not executed. You can store the query in a variable for later use. This kind of object enables you to build up a query using chaining syntax. The actual db search is executed when you finally chain the method `.exec()`. You always need to pass your callback to this last method. There are many query helpers, here we'll use the most commonly used.

</section>

## Instructions

<section id='instructions'>

Modify the `queryChain` function to find people who like the food specified by the variable named `foodToSearch`. Sort them by `name`, limit the results to two documents, and hide their age. Chain `.find()`, `.sort()`, `.limit()`, `.select()`, and then `.exec()`. Pass the `done(err, data)` callback to `exec()`.

### Further Readings

If you are eager to learn and want to go deeper, You may look at:

- Indexes ( very important for query efficiency ),
- Pre/Post hooks,
- Validation,
- Schema Virtuals and Model, Static, and Instance methods,

</section>

## Tests

<section id='tests'>

```yml
tests:
  - text: Chaining query helpers should succeed
    testString: |
      getUserInput => $.ajax({url: getUserInput('url') + '/_api/query-tools', type: 'POST', contentType:'application/json', data: JSON.stringify([{name: 'Pablo', age: 26, favoriteFoods: ['burrito', 'hot-dog']}, {name: 'Bob', age: 23, favoriteFoods: ['pizza', 'nachos']}, {name: 'Ashley', age: 32, favoriteFoods: ['steak', 'burrito']}, {name: 'Mario', age: 51, favoriteFoods: ['burrito', 'prosciutto']} ]) }).then(data => {
        assert.isArray(data, 'the response should be an Array');
        assert.equal(data.length, 2, 'the data array length is not what expected');
        assert.notProperty(data[0], 'age', 'The returned first item has too many properties');
        assert.equal(data[0].name, 'Ashley', 'The returned first item name is not what expected');
        assert.notProperty(data[1], 'age', 'The returned second item has too many properties');
        assert.equal(data[1].name, 'Mario', 'The returned second item name is not what expected');
        }, xhr => { throw new Error(xhr.responseText); })
```

</section>

## Challenge Seed

<section id='challengeSeed'>

</section>

## Solution

<section id='solution'>

```js
/**
  Backend challenges don't need solutions, 
  because they would need to be tested against a full working project. 
  Please check our contributing guidelines to learn more.
*/
```

</section>