Storage

Ampt provides an easy-to-use file storage service that can be used to serve any type of binary or text file. When shared publicly, files will be automatically served all around the world via our global CDN.

Interact with the storage service using the storage interface of the @ampt/sdk.

Defining Buckets #

Buckets are the separate folders to store the files belonging to same domain. For example, you can have a bucket named students to store any files related to students and you can have another bucket named books for the "book" entity.

The root bucket is available by calling storage() without any parameters.

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import { storage } from "@ampt/sdk";

// define a new bucket
const students = storage("students");
// get the root bucket
const rootBucket = storage();

Storing Files #

Files can be stored by passing the binary string to the write function. This could either be files uploaded via an HTTP request, or modifying any existing files and saving the changes. Note that if a file exists at the provided path, it will be replaced with the new file.

You can optionally omit a path for the file, which will save it at the "root" directory.

Metadata and custom mimetypes can also be passed to the file.

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const students = storage('students');
// write file to /students/your/path/binaryData.ext
await students.write("/your/path/binaryData.ext", binaryData);
await students.write('/your/path/binaryData.ext', binaryData, { metadata: { isThisAFile: true } })
await students.write('/your/path/binaryData.ext', binaryData, { type: ‘application/octet-stream’ })
// this goes to root of /students
await students.write('/', binaryData)

Reading Files #

Files can be read into memory as either a ReadableStream or a Buffer. If no options are passed, a ReadableStream is returned by default. Also included is readBuffer for ease of use, if you want to only use buffers without any extra arguments. To read the file, the absolute directory must be passed. If the file does not exist, undefined is returned.

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const students = storage("students");
const stream = await students.read("binaryData.ext");

const buffer = await students.read("binaryData.ext", { buffer: true });
const buffer = await students.readBuffer("/your/path/binaryData.ext");

Copying and Moving Files #

Files can be moved or copied to any directory. If a destination directory does not exist, it will be created.

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const students = storage("students");
await students.move("binaryData.ext", "bin");
// binaryData is now located at bin/binaryData.ext

await students.copy("/bin/binaryData.ext", "bin-copy");
// binaryData is now located at both bin/binaryData.ext and bin-copy/binaryData.ext

Checking File Existence #

To avoid a read operation, you may want to just check if a file exists before going forward.

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const students = storage("students");

const exists = await students.exists("/bin/binaryData.ext");
const doesNotExist = await students.exists("/not-real/binaryData.ext");

File Information and Metadata #

You can retrieve when a file was last modified, size, content type, and any saved metadata using stat.

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const students = storage.bucket("students");
const { lastModified, size, metadata, type } = await students.stat(
  "/your/path/binaryData.ext"
);

Listing Files #

Files in a bucket can be listed either as a whole or per folder. To list all subfolders recursively, you can pass a recursive option to list everything in all subfolders under the initial path.

list returns an async generator, allowing for controlled iteration through your files.

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const students = storage("students");
const list = await students.list("bin", { pageSize: 1 });
const page1 = await list.next();
// ['binaryData.ext']

const pages = await students.list("/", { recursive: true, pageSize: 10 });
const allFiles = [];
for await (const page of pages) {
  allFiles.push(...page);
}
// ['bin/binaryData.ext', 'bin-copy/binaryData.ext']

Removing Files #

Files can be removed using the remove function.

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await storage("students").remove("/bin/binaryData.ext");

Upload and Download URLs #

URLs for both uploading and downloading files from a bucket can be generated using getDownloadUrl and getUploadUrl. A second parameter can be passed to set the expiration period for a URL, as a number in seconds. The default is 1 hour (3600s).

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const downloadUrl = await storage("students").getDownloadUrl(
  "bin-copy/binaryData.ext"
);

const longDownloadUrl = await storage("students").getDownloadUrl(
  "bin-copy/binaryData.ext",
  7200
);

const uploadUrl = await storage("students").getUploadUrl(
  "bin-copy/doesNotExistYet.ext"
);

If the file you're uploading is expected to be larger than 6MB, you should create an upload URL and use the PUT method to upload the file directly to Ampt Storage.

Listeners #

You can listen for certain events with storage.on. As of now, you can fire dispatch only for write and remove events. The listener accepts any glob file patterns, and will react to all events with an asterisk *.

Storage events contain both the path of the file, and the event name (write or remove).

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storage().on("write:user-uploads/*", async (event) => {
  // event = { path: user-uploads/picture.jpeg, name: 'write' }
});

storage().on("*", async (event) => {
  // reacts to all write/remove events
});

storage().on("write:*.txt", async (event) => {
  // reacts to all .txt file writes
});

storage("students").on("write", async (event) => {
  // only reacts to changes in the "students" bucket
});