> ## Documentation Index
> Fetch the complete documentation index at: https://firebridge.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Change Types

> Detecting document changes within Firestore Cloud Functions is essential for real-time data handling. The `getChangeType` utility facilitates this by categorizing document changes, making it easier to implement responsive and efficient cloud functions.

## Overview

Firestore Cloud Functions allow you to run backend code in response to events triggered by Firestore operations. The `getChangeType` utility is designed to work seamlessly within this environment, identifying whether a document in Firestore has been created, updated, or deleted. This enables precise and effective event handling in cloud functions.

### Change Types

* `create`: Indicates a new document was added.
* `update`: Represents updates to an existing document.
* `delete`: Occurs when a document is removed.

### Usage in Cloud Functions

#### Setting up a Firestore Trigger

To use `getChangeType` in a Firestore Cloud Function:

```ts theme={null}
import * as functions from 'firebase-functions'
import { firestore } from 'firebase-admin'
import { getChangeType } from '@firebridge/cloud'

// Cloud Function listening to changes in a specific collection
export const onDocumentChange = functions.firestore
  .document('/your-collection/{docId}')
  .onWrite((change, context) => {
    // Determine the type of change
    const changeType = getChangeType(change)

    switch (changeType) {
      case 'create':
        // Handle creation logic
        console.log(`New document created: ${context.params.docId}`)
        break
      case 'update':
        // Handle update logic
        console.log(`Document updated: ${context.params.docId}`)
        break
      case 'delete':
        // Handle deletion logic
        console.log(`Document deleted: ${context.params.docId}`)
        break
    }
  })
```

## `DocumentChangeType` Explanation

The `DocumentChangeType` type alias simplifies working with Firestore changes in TypeScript, ensuring you always handle the correct type of document change.

```ts theme={null}
type DocumentChangeType = 'create' | 'update' | 'delete'
```

## Practical Applications

* **Data Validation**: Validate or transform data when a new document is created or updated.
* **Notification Systems**: Trigger notifications on data changes, such as sending an email when a new document is added.
* **Data Synchronization**: Sync data with other systems or databases on document changes.

<Warning>
  When working with Cloud Functions, it's important to handle each type of
  document change correctly to maintain data integrity and ensure the desired
  workflow.
</Warning>

## Best Practices

* Thoroughly test your Cloud Functions to ensure they behave as expected for each type of document change.
* Optimize your function's execution time and resource usage, especially if your Firestore operations are frequent and large in scale.
* Document the purpose and expected behavior of your Cloud Functions for future reference and maintenance.

***

With these guidelines, you can effectively integrate `getChangeType` into your Firestore Cloud Functions, enhancing your application's responsiveness and efficiency in handling real-time data changes.