# Field transformations (services)
## Introduction
**Field transformations** can be defined to change the value of data pulled from a source system before it is pushed to a destination system. A **transformation** is comprised of one or more **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).
## 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 service ](https://doc.wearepatchworks.com/product-documentation/patchworks-services/working-with-services/accessing-services)and select the **mappings** tab:
**Step 2**\
The **field mapping** page is displayed with mappings organised in logical categories, based on the **destination** connector:
{% hint style="info" %}
If a transformation has been applied to a field mapping already, it is displayed with a transformation icon:\
{% endhint %}
**Step 3**\
Find the mapping that you wish to update with a transformation, then click anywhere in the row to expand details and choose the **edit** option:
...the field mapping is displayed in edit mode:
**Step 4**\
Click the **add transformation** button:
...the **transformation editor** is displayed:
**Step 5**\
Click the **add new function** button:\
\
\
...settings for the new function are shown:
**Step 6**\
Click in the **function name** field and select the type of function that you'd like to add:
**Step 7**\
Depending on the type of function you select, additional fields are displayed for you to complete. Update these as required and click the **save function** button:
...the new function is added to the **transformation editor**:\
\
{% hint style="info" %}
If your transform uses a **type** conversion (for example, converting a string type to a date type) and your transformed data type does not match the destination, you will need to add a **convert to function** before the function can be saved.
{% endhint %}
**Step 8**\
Repeat these steps to add any more functions that you need. When you're ready, click the **save transformation** button (at the bottom of the **transformation editor** page):\
\
...you'll exit back to the field mapping in edit mode:
**Step 9**\
Click the **done** button to confirm changes:\
\
## Deleting an existing function or transformation
**Step 1**\
Follow steps [1 to 3 above](#adding-a-new-transformation) to edit the required field mapping. The mapping is shown in edit mode and - if transformations are present - you will see an **edit transformation** button:
**Step 2**\
Select the **edit transformation** button to open the **transformation editor**. Here, any existing functions for the transformation are shown:
**Step 3**\
Select the function that you wish to remove - settings for this function are displayed in the right-hand panel:
**Step 4**\
Click the **delete function** button:
**Step 5**\
When prompted, confirm that you wish to proceed with this operation - the function is removed.
**Step 6**\
Keep in mind that a transformation may contain multiple functions. If no other functions are defined for this transformation, click the **delete transformation** button:\
\
...if other functions are defined for this transformation, click the **save** transformation button.
{% endhint %}
**Step 3**\
Find the mapping that you wish to update with a transformation, then click anywhere in the row to expand details and choose the **edit** option:
