# How to use Jmespath to map to customFields ANS values in Outbound Feeds

Source: https://dev.arcxp.com/arc-io/developer-docs/how-to-use-jmespath-to-map-to-customfields-ans-values-in-outbound-feeds/

How to Use jmespath to Map to customFields ANS Values in Outbound Feeds

If you use a customField to map an Arc XP Native Specification (ANS) field when populating a feed, you must use the [Jmespath](https://jmespath.org/) syntax. This document presents examples of the most common use cases with the Jmespath patterns you must use when mapping ANS fields.

## Mapping to a single field

This example maps the ANS headline to the title of an article. This is the default value that is used in the Title customField:

```
headlines.basic
```

## Mapping to multiple fields

Suppose your organization creates shorter mobile friendly headlines for stories with very long headlines using `headlines.mobile`. But `headlines.mobile` is only populated when the headline is too long. You can use `headlines.mobile` and fall back to `headlines.basic` if it’s not filled out, as in the following example:

```
headlines.mobile || headlines.basic
```

## Mapping to a field in an object

If you want to get all the authors names from a story, the `credits.by` field contains an array of author objects. You can get a list of the authors names using the following. Notice that the position of arrays must be included:

```
credits.by[].name
```

If you only want the first authors name you can specify the index position. You must add brackets around the name so it still returns the results as a list.

```
credits.by[0].[name]
```

This example includes multiple fields to return the authors byline first and fall back to name:

```
credits.by[].additional_properties[].original.byline || credits.by[].name
```