> ## Documentation Index
> Fetch the complete documentation index at: https://docs.chronosphere.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Nest keys

export const entity_0 = "nest keys processing rule"

The nest keys [processing rule](/ingest/pipeline/processing-rules) moves the value of a
specified source key into an object nested under a specified destination key.

## Configuration parameters

Use the parameters in this section to configure the {entity_0}. The
Telemetry Pipeline web interface uses the items in the **Name** column to
describe these parameters. [Pipeline configuration files](/ingest/pipeline/v2/configure/config-files)
use the items in the **Key** column as YAML keys.

| Name                    | Key           | Description                                                                                                                                                                                                                                                                                                                          | Default                |
| ----------------------- | ------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------- |
| **Source key**          | `src`         | Required. The key to nest under **Destination key**. This can be either a flat key/value pair or the key to an object.                                                                                                                                                                                                               | *none*                 |
| **Destination key**     | `dst`         | Required. The key of the object to store your nested data. If no matching key exists, create a new key and set its value accordingly.                                                                                                                                                                                                | *none*                 |
| **Match case** checkbox | `matchCase`   | Indicates whether the regular expression is case-sensitive.                                                                                                                                                                                                                                                                          | Not selected           |
| **Regex engine**        | `regexEngine` | Required. The [engine](/ingest/pipeline/processing-rules#regex-engines) to parse your regular expression. Accepted values: `GNU`, `Oniguruma`, `PCRE2`, `POSIX`, `TRE`.                                                                                                                                                              | `PCRE2`                |
| **Regex mode** checkbox | `regexMode`   | Indicates whether to treat the value of **Source key** as a regular expression.                                                                                                                                                                                                                                                      | Not selected / `false` |
| **Merge** checkbox      | `merge`       | If selected, and if **Destination key** is the key to an existing object that already contains data, the nest keys rule moves the new nested data into **Destination key** without overwriting its original data. However, if **Destination key** is a flat key/value pair, its value is overwritten and replaced with a new object. | Not selected           |
| **Comment**             | `comment`     | A custom note or description of the rule's function. This text is displayed next to the rule's name in the **Actions** list in the processing rules interface.                                                                                                                                                                       | *none*                 |

## Examples

Using the nest keys processing rule lets you restructure your telemetry data
by storing key/value pairs inside a parent object.

### New object

For example, given this sample log data:

```json theme={null}
{"timestamp":"2023-03-28T09:08:41.64283645Z","user_id":3,"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:42.643343109Z","user_id":4,"page_id":10,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:48.643600498Z","user_id":1,"page_id":50,"action":"click"}
{"timestamp":"2023-03-28T09:08:50.643773688Z","user_id":5,"page_id":40,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:51.643932272Z","user_id":1,"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:56.644080944Z","user_id":2,"page_id":40,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.64425954Z","user_id":3,"page_id":30,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.644317046Z","user_id":1,"page_id":20,"action":"view"}
{"timestamp":"2023-03-28T09:09:10.64447719Z","user_id":2,"page_id":50,"action":"purchase"}
{"timestamp":"2023-03-28T09:09:17.644810963Z","user_id":2,"page_id":10,"action":"view"}
{"timestamp":"2023-03-28T09:09:20.644994805Z","user_id":1,"page_id":50,"action":"view"}
```

A processing rule with the **Source key** value `user_id` and the **Destination key**
value `account` returns the following result:

```json theme={null}
{"timestamp":"2023-03-28T09:08:41.64283645Z","user_id":3,"account":{"user_id":3},"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:42.643343109Z","user_id":4,"account":{"user_id":4},"page_id":10,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:48.643600498Z","user_id":1,"account":{"user_id":1},"page_id":50,"action":"click"}
{"timestamp":"2023-03-28T09:08:50.643773688Z","user_id":5,"account":{"user_id":5},"page_id":40,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:51.643932272Z","user_id":1,"account":{"user_id":1},"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:56.644080944Z","user_id":2,"account":{"user_id":2},"page_id":40,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.64425954Z","user_id":3,"account":{"user_id":3},"page_id":30,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.644317046Z","user_id":1,"account":{"user_id":1},"page_id":20,"action":"view"}
{"timestamp":"2023-03-28T09:09:10.64447719Z","user_id":2,"account":{"user_id":2},"page_id":50,"action":"purchase"}
{"timestamp":"2023-03-28T09:09:17.644810963Z","user_id":2,"account":{"user_id":2},"page_id":10,"action":"view"}
{"timestamp":"2023-03-28T09:09:20.644994805Z","user_id":1,"account":{"user_id":1},"page_id":50,"action":"view"}
```

This rule moved the `user_id` key/value pair into a new object named `account`.

### Merge into existing object

You can also use the **Merge** setting to nest data within an existing object.
For example, given this sample log data:

```json theme={null}
{"timestamp":"2023-03-28T09:08:41.64283645Z","user":{"account":{"vip":"no","id":3},"device":"mobile"},"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:42.643343109Z","user":{"account":{"vip":"yes","id":4},"device":"desktop"},"page_id":10,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:48.643600498Z","user":{"account":{"vip":"no","id":1},"device":"desktop"},"page_id":50,"action":"click"}
{"timestamp":"2023-03-28T09:08:50.643773688Z","user":{"account":{"vip":"yes","id":5},"device":"mobile"},"page_id":40,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:51.643932272Z","user":{"account":{"vip":"no","id":1},"device":"other"},"page_id":30,"action":"purchase"}
{"timestamp":"2023-03-28T09:08:56.644080944Z","user":{"account":{"vip":"yes","id":2},"device":"mobile"},"page_id":40,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.64425954Z","user":{"account":{"vip":"no","id":3},"device":"desktop"},"page_id":30,"action":"click"}
{"timestamp":"2023-03-28T09:09:03.644317046Z","user":{"account":{"vip":"no","id":1},"device":"desktop"},"page_id":20,"action":"view"}
{"timestamp":"2023-03-28T09:09:10.64447719Z","user":{"account":{"vip":"yes","id":2},"device":"desktop"},"page_id":50,"action":"purchase"}
{"timestamp":"2023-03-28T09:09:17.644810963Z","user":{"account":{"vip":"yes","id":2},"device":"other"},"page_id":10,"action":"view"}
{"timestamp":"2023-03-28T09:09:20.644994805Z","user":{"account":{"vip":"no","id":1},"device":"mobile"},"page_id":50,"action":"view"}
```

A processing rule with the **Source key** value `action`, the **Destination key**
value `user`, and the **Merge** setting enabled returns the following result:

```json theme={null}
{"user":{"account":{"id":3,"vip":"no"},"action":"purchase","device":"mobile"},"timestamp":"2023-03-28T09:08:41.64283645Z","page_id":30,"action":"purchase"}
{"user":{"account":{"id":4,"vip":"yes"},"action":"purchase","device":"desktop"},"timestamp":"2023-03-28T09:08:42.643343109Z","page_id":10,"action":"purchase"}
{"user":{"account":{"id":1,"vip":"no"},"action":"click","device":"desktop"},"timestamp":"2023-03-28T09:08:48.643600498Z","page_id":50,"action":"click"}
{"user":{"account":{"id":5,"vip":"yes"},"action":"purchase","device":"mobile"},"timestamp":"2023-03-28T09:08:50.643773688Z","page_id":40,"action":"purchase"}
{"user":{"account":{"id":1,"vip":"no"},"action":"purchase","device":"other"},"timestamp":"2023-03-28T09:08:51.643932272Z","page_id":30,"action":"purchase"}
{"user":{"account":{"id":2,"vip":"yes"},"action":"click","device":"mobile"},"timestamp":"2023-03-28T09:08:56.644080944Z","page_id":40,"action":"click"}
{"user":{"account":{"id":3,"vip":"no"},"action":"click","device":"desktop"},"timestamp":"2023-03-28T09:09:03.64425954Z","page_id":30,"action":"click"}
{"user":{"account":{"id":1,"vip":"no"},"action":"view","device":"desktop"},"timestamp":"2023-03-28T09:09:03.644317046Z","page_id":20,"action":"view"}
{"user":{"account":{"id":2,"vip":"yes"},"action":"purchase","device":"desktop"},"timestamp":"2023-03-28T09:09:10.64447719Z","page_id":50,"action":"purchase"}
{"user":{"account":{"id":2,"vip":"yes"},"action":"view","device":"other"},"timestamp":"2023-03-28T09:09:17.644810963Z","page_id":10,"action":"view"}
{"user":{"account":{"id":1,"vip":"no"},"action":"view","device":"mobile"},"timestamp":"2023-03-28T09:09:20.644994805Z","page_id":50,"action":"view"}
```

This rule moved the `action` key/value pair into the `user` object, but kept the
existing key/value pairs that were already stored in `user`.

## Related rules

For a processing rule with the opposite effect, see
[flatten subrecord](/ingest/pipeline/processing-rules/flatten-subrecord)
or [lift submap](/ingest/pipeline/processing-rules/lift-submap).