---
title: Anatomy of a complex query using extensions
slug: '1464'
canonical_url: https://docs.coveo.com/en/1464/
collection: build-a-search-ui
source_format: adoc
---
# Anatomy of a complex query using extensions

You can obtain insightful contextual results using nested [queries](https://docs.coveo.com/en/231/) on many lines using [query extensions](https://docs.coveo.com/en/1397/).
[Coveo for Salesforce](https://docs.coveo.com/en/1243/) takes advantage of such complex [queries](https://docs.coveo.com/en/231/) to present valuable contextual information in Coveo [Insight Panels](https://docs.coveo.com/en/2898/).

You first need to know that in a multi-line [query](https://docs.coveo.com/en/231/), the lines are processed from the first to the last.
The result set from the first line is available to the next lines and so forth.

> **Leading practice**
>
> [Use aliases](https://docs.coveo.com/en/1465#use-aliases) to split the [query](https://docs.coveo.com/en/231/) into chunks that are easier to understand, and then use one or more aliases as building blocks on subsequent lines to nest [queries](https://docs.coveo.com/en/231/).

A minimum knowledge of [standard query extensions](https://docs.coveo.com/en/1462/) and of the content of your [index](https://docs.coveo.com/en/204/) and Salesforce [fields](https://docs.coveo.com/en/200/) will help you understand existing complex [queries](https://docs.coveo.com/en/231/) and imagine new ones.

The following example presents how a complex query can be used to present recent emails in a Coveo Insight Panel:


[source,javascript,subs="attributes+"]
```
pass:[{{accounts=$type(name:'Account') @title="{!>Name}"}}]
{{contacts=$join(fromResultSet: {{accounts}}, toResultSet: $type(name: 'Contact'), field: '@sfaccountid')}}
{{emailAddresses=$valuesOfField(field: '@sfemail', resultSet: {{contacts}})}}
$emailsExchangedWithThoseAddresses(addresses: {{emailAddresses}})
NOT @isattachment
$sort(criteria: 'datedescending')
```

In short, this [query](https://docs.coveo.com/en/231/) lists decreasingly recent email messages exchanged with people connected to the account currently selected in Salesforce.

## Line 1

[source,javascript,subs="attributes+"]
```
pass:[{{accounts=$type(name:'Account') @title="{!>Name}"}}]
```

Line 1 creates the `accounts` [alias](https://docs.coveo.com/en/176/) that will only contain search results of type `Account` matching the currently selected Salesforce account.

In more detail, the standard extension `$type` specifies that the result set of the [alias](https://docs.coveo.com/en/176/) contains [items](https://docs.coveo.com/en/210/) of type `Account`.
The [field](https://docs.coveo.com/en/200/) query `@title="{!>Name}"` filters only accounts for which the content of the `title` [index](https://docs.coveo.com/en/204/) [field](https://docs.coveo.com/en/200/) is equal to the name of the currently selected account in Salesforce.

> **Note**
>
> In the [index](https://docs.coveo.com/en/204/), the name of a Salesforce account object is stored in the `title` field.
> In the context of Salesforce, `{!>Name}` returns the name of the currently selected account.

## Line 2

```javascript
{{contacts=$join(fromResultSet: {{accounts}}, toResultSet: $type(name: 'Contact'), field: '@sfaccountid')}}
```

Line 2 creates the `contacts` [alias](https://docs.coveo.com/en/176/) that will contain all of the contacts connected with the accounts from Line 1.

In more detail, the standard extension `$join` specifies the content of the [alias](https://docs.coveo.com/en/176/) by taking the [alias](https://docs.coveo.com/en/176/) of Line 1 as the input `(fromResultSet: {{accounts}})`, and returns [items](https://docs.coveo.com/en/210/) of type Contact `(toResultSet: $type(name: 'Contact'))` that have the same Salesforce account ID (`sfaccountid` field value) as [items](https://docs.coveo.com/en/210/) in the `fromResultSet`.

## Line 3

```javascript
{{emailAddresses=$valuesOfField(field: '@sfemail', resultSet: {{contacts}})}}
```

Line 3 creates the `emailAddresses` [alias](https://docs.coveo.com/en/176/) that will contain the list of email addresses corresponding to the list of contacts from Line 2.

In more detail, the standard extension `$valuesOfField` specifies the content of the [alias](https://docs.coveo.com/en/176/) by building a list of Salesforce email addresses `(field: '@sfemail')` for the contacts in the `contacts` [alias](https://docs.coveo.com/en/176/) created on Line 2.

## Line 4

```javascript
$emailsExchangedWithThoseAddresses(addresses: {{emailAddresses}})
```

Line 4 uses the `$emailsExchangedWithThoseAddresses` standard extension to get all of the emails exchanged with the list of email addresses from the `emailAddresses` [alias](https://docs.coveo.com/en/176/) created with Line 3.

## Line 5

```javascript
NOT @isattachment
```

Line 5 filters out the results from Line 4 that are attachments.

In more detail, the line uses a Boolean operator (`NOT`) with a [field](https://docs.coveo.com/en/200/) query `@isattachment` to filter on the `isattachment` Boolean [index](https://docs.coveo.com/en/204/) [field](https://docs.coveo.com/en/200/).

In the context of a Coveo [Insight Panel](https://docs.coveo.com/en/2898/), you usually only want the messages themselves.
The user can always click a result to open the email in the original email application and review attachments in this context.

## Line 6

```javascript
$sort(criteria: 'datedescending')
```

Line 6 uses the `$sort` standard extension to sort email messages by inverse time values.

## What's next?

Review examples of [query extensions](https://docs.coveo.com/en/1182/) that are specific to [Coveo for Salesforce](https://docs.coveo.com/en/1404/).