# Array join transform function
## Introduction
The **array join** transform function is used to join elements of an array as a string, with a user-defined delimiter. For example, you might have product data in an array:
{% code lineNumbers="true" %}
```json
{
"fruit_in": [
"Apples",
"Oranges",
"Pears",
"Grapes"
]
}
```
{% endcode %}
...and need to convert these items to a string before pushing to a single destination field (with each item in the string delimited by a character of your choice):
{% code lineNumbers="true" %}
```json
{"fruit_out":"Apples,Oranges,Pears,Grapes"}
```
{% endcode %}
## Adding an array join transform
**Step 1**\
In your process flow, access settings for your map shape:
**Step 2**\
Select the **add transform** icon for the required mapping rule - for example:
**Step 3**\
Click the **add transform** button:
**Step 4**\
Click in the **name** field to access a list of all available transform functions, then select **join** from the **array** category:
**Step 5**\
In the delimiter field, enter the character that you want to use to delimit each array field in the string:
{% hint style="info" %}
A space is a valid character. If you want to join array items with no spacing or other delimiters, leave this field empty.
{% endhint %}
**Step 6**\
Click the **add field** button:
**Step 7**\
Click in **source fields** and select the source field to be used for this transform:
**Step 8**\
Accept your changes (twice).
**Step 9**\
Save the transform. You'll notice that the transform icon is updated to indicate that a transform function is present for the mapping row - for example:
## Related pages
* [Mapping array fields](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/standard-shapes/map-shape/mappings-tips-and-tricks/mapping-array-fields)
