21.
Cloud Storage
Written by Harun Wangereka
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With Realtime Database and Cloud Firestore, you saved data to the database. But what about files like photos, for example? While small pieces of data like posts, comments or users tend to be a few kilobytes of text, photos are much larger. Storing and retrieving photos extends the startup and loading time when reading the database. You don’t want to store photos in a database because it should be fast.
In this chapter, you’ll learn how to store media files using another Firebase feature — Cloud Storage. You’ll learn how to store an image in the cloud and how to get a URL to the image to display it in your app.
Note: If you skipped previous chapters, you need to set up Firebase to follow along. Do the following steps:
1.Create a project in the Firebase console.
2.Enable Google sign-in.
3.Set security rules to test mode to allow everyone read and write access.
4.Add google-service.json to both starter and final projects.
Note: To see how to do the steps above, go back to “Chapter 12: Firebase Overview” and “Chapter 13: Introduction to Firebase Realtime Database”.
Be sure to use the starter project from this chapter by opening the 21-cloud-storage folder and its starter project from the projects folder, rather than continuing with the final project you previously worked on. This chapter’s starter project has a few things added to it, including placeholders for the code to add in this chapter.
Cloud Storage Overview
Cloud Storage is a Firebase product used for saving files associated with your app. You can use it to store large documents or media files like images or videos.
Since Cloud Storage operates with large files, it’s fundamental to provide robust network connection mechanisms and fallbacks. Cloud Storage handles all the potential network problems for you. Depending on your connection, upload or download can take a while. If you lose the network connection in the middle of an upload or a download, the transfer will continue where it left off, after you reconnect to the network. This makes transferring your data very efficient.
Cloud Storage also has security features that will safely store your files away from the public. You can decide who can write data to and read data from the storage.
The foundations of Cloud Storage are the folders that you create to organize your data. You can then decide which users can access which folders.
There’s more theory you could learn, but for now, you’ll use the Firebase console to set up Cloud Storage. You’ll use the WhatsUp app to store, download and display images to users on the app screen.
Getting started
Open your WhatsUp app in the Firebase console. Select Storage from the Build menu on the left.
Integrating Cloud Storage
Open the starter project for this chapter. Build and run. You’ll see the main screen for adding posts.
//1
val photosReference = firebaseStorage.getReference(PHOTOS_REFERENCE)
//2
selectedImageUri.lastPathSegment?.let { segment ->
//3
val photoReference = photosReference.child(segment)
//4
photoReference.putFile(selectedImageUri)
//5
.continueWithTask(Continuation<UploadTask.TaskSnapshot, Task<Uri>> { task ->
val exception = task.exception
if (!task.isSuccessful && exception != null) {
throw exception
}
return@Continuation photoReference.downloadUrl
})
//6
.addOnCompleteListener { task ->
if (task.isSuccessful) {
val downloadUri = task.result
onSuccessAction(downloadUri.toString())
}
}
}
private val pickImages = registerForActivityResult(ActivityResultContracts.GetContent()) { uri ->
uri?.let { selectedImageUri ->
binding.progressbar.visibility = View.VISIBLE
cloudStorageManager.uploadPhoto(selectedImageUri, ::onPhotoUploadSuccess)
}
}
pickImages.launch(IMAGE_TYPE)
Key points
- Cloud Storage is a Firebase product used for saving files associated with your app.
- If you lose a network connection in the middle of the upload or a download, the transfer will continue where it left off after you reconnect to the network.
- Cloud Storage also has security features that will make your files secure.
- The foundations of Cloud Storage are folders that you can create to organize your data.
Where to go from here?
This chapter was only an introduction to Cloud Storage to show you how to store media files to the cloud. You learned how to set up Cloud Storage and how to upload and download files from it. Cloud Storage has many other features. To learn more about them visit the official guidelines https://firebase.google.com/docs/storage/android/start.