# Working with field transformations
## Introduction
**Field transformations** can be defined to change the value of a data field pulled from a source system before it is sent to its target. A **transformation** is comprised of one or more [functions](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/standard-shapes/map-shape/working-with-field-transformations/available-transform-functions).
This page explains how to [add a new transformation](#adding-a-new-transformation) for a field mapping, and [how to remove functions and transformations](#deleting-an-existing-function-or-transformation).
{% hint style="info" %}
For a summary of available transform functions please see the [Field mapping transformation function reference](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/standard-shapes/map-shape/working-with-field-transformations/available-transform-functions) section.
{% endhint %}
{% hint style="info" %}
For information about adding a field transformation using a cross-reference lookup table, please see our [cross-reference lookups](https://doc.wearepatchworks.com/product-documentation/process-flows/cross-reference-lookups) section.
{% endhint %}
## Adding a new transformation
To add a new transformation for a field mapping, you start by adding a new transformation and then build the required functions. To do this, follow the steps below:
**Step 1**\
Access the required process flow and then edit the map shape to be updated with a transform:
**Step 2**\
Find the mapping that you want to update, then click the **transform** icon (between source and target elements). For our example, we're going to add a prefix to the 'id' field:
**Step 3**\
Click the **add transform** button:
**Step 4**\
Use the **select a function** field to choose the type of function that you need to use (functions are organised by type):
**Step 5**\
Depending on the type of function you select, additional fields are displayed for you to complete. Update these as required - for our example we're adding some text to be added as a prefix:
**Step 6**\
Now we need to confirm which source field this transform field should be applied for - click the **add field** button:
**Step 7**\
Select the required field:
{% hint style="info" %}
In straightforward scenarios, this will typically be the same source field as defined for the mapping row. However, more complex scenarios may prompt multiple options here - for example, if you apply multiple transforms to the same mapping.
{% endhint %}
**Step 8**\
Accept your changes.
**Step 9**\
Add more fields if necessary.
**Step 10**\
When you're satisfied that all required fields have been added, accept changes and then save the shape settings.
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