Storage Create a Reference

The contents of this page are based on the original Firebase Documentation

Your files are stored in a Google Cloud Storage bucket. The files in this bucket are presented in a hierarchical structure, just like the file system on your local hard disk, or the data in the Firebase Realtime Database. By creating a reference to a file, your app gains access to it. These references can then be used to upload or download data, get or update metadata or delete the file. A reference can either point to a specific file or to a higher level node in the hierarchy.

If you've used the Firebase Realtime Database, these paths should seem very familiar to you. However, your file data is stored in Google Cloud Storage, not in the Realtime Database.

Create a Reference

Create a reference to upload, download, or delete a file, or to get or update its metadata. A reference can be thought of as a pointer to a file in the cloud. References are lightweight, so you can create as many as you need. They are also reusable for multiple operations.

References are created using the FirebaseStorage service and calling its reference method.

storage = StorageANE.storage;
var storageRef:StorageReference = storage.reference();

You can create a reference to a location lower in the tree, say 'images/space.jpg', by using the child method on an existing reference.

// Create a child reference
// imagesRef now points to "images"
var imagesRef:StorageReference = storageRef.child("images");

// Child references can also take paths delimited by '/'
// spaceRef now points to "images/space.jpg"
// imagesRef still points to "images"
var spaceRef:StorageReference = storageRef.child("images/space.jpg")

// This is equivalent to creating the full reference
var storagePath:String = "\(your_firebase_storage_bucket)/images/space.jpg";
spaceRef = storage.reference(storagePath);

Navigate with References

You can also use the parent and root methods to navigate up in our file hierarchy. parent navigates up one level, while root navigates all the way to the top.

// Parent allows us to move to the parent of a reference
// imagesRef now points to 'images'
var imagesRef:StorageReference = storageRef.parent();

// Root allows us to move all the way back to the top of our bucket
// rootRef now points to the root
var rootRef:StorageReference = storageRef.root();

child, parent, and root can be chained together multiple times, as each returns a reference. The exception is the parent of root, which is null.

// References can be chained together multiple times
// earthRef points to "images/earth.jpg"
var earthRef:StorageReference = spaceRef.parent().child("earth.jpg");

// nullRef is null, since the parent of root is null
var nullRef:StorageReference = spaceRef.root().parent()

Reference Properties

You can inspect references to better understand the files they point to using the path, name, and bucket properties. These properties get the file's full path, name, and bucket.

// Reference's path is: "images/space.jpg"
// This is analogous to a file path on disk
spaceRef.path;

// Reference's name is the last segment of the full path: "space.jpg"
// This is analogous to the file name
spaceRef.name;

// Reference's bucket is the name of the storage bucket where files are stored
spaceRef.bucket;

Limitations on References

Reference paths and names can contain any sequence of valid Unicode characters, but certain restrictions are imposed including:

1. Total length of reference.fullPath must be between 1 and 1024 bytes when UTF-8 encoded.
2. No Carriage Return or Line Feed characters.
3. Avoid using #, [, ], *, or ?, as these do not work well with other tools such as the Firebase Realtime Database or gsutil.