# save

Learn how to apply the changes to the entity.

This method builds the patch and applies the changes.

> **Atomicity**
>
> When a patch is applied, it works on an all-or-nothing basis to keep things consistent. This means that either all changes are applied together, or none are applied at all.

## Signature

This method has the following signature:

```ts
patch.save(): Promise<Event>
```

The return is a `Promise` that resolves to the event that records the changes.

## Example

Here is a basic example of how to use this method:

```ts
patch.set('address.city', 'New York')
  .save()
  .then(() => console.log('Patch successfully sent'));
```