Class AzureFileStorage

Creates a new instance of AzureFileStorage.

Initializes the connection to Azure Blob Storage using environment variables. Throws an error if any required environment variables are missing.

Checks if Azure Blob provider is properly configured. Returns true if account name and container name are present.

Copies a blob within Azure Blob Storage.

This method creates a copy of a blob at a new location without removing the original. It uses a SAS URL to provide the source blob access for the copy operation.

Example

// Create a backup copy of an important file
const copied = await azureStorage.CopyObject(
  'documents/contract.pdf',
  'backups/contract_2024-05-16.pdf'
);

if (copied) {
  console.log('File copied successfully');
} else {
  console.log('Failed to copy file');
}
Copy

Creates a directory (virtual) in Azure Blob Storage.

Since Azure Blob Storage doesn't have a native directory concept, this method creates a zero-byte blob with a trailing slash to simulate a directory. The blob has a special content type to indicate it's a directory.

Example

// Create a new directory structure
const created = await azureStorage.CreateDirectory('documents/reports/annual/');

if (created) {
  console.log('Directory created successfully');
} else {
  console.log('Failed to create directory');
}
Copy

Creates a pre-authenticated download URL for a blob in Azure Blob Storage.

This method generates a Shared Access Signature (SAS) URL that allows for downloading a blob without needing the Azure Storage account credentials. The URL is valid for 10 minutes and can only be used for reading the specified blob.

Example

// Generate a pre-authenticated download URL for a PDF file
const downloadUrl = await azureStorage.CreatePreAuthDownloadUrl('documents/report.pdf');

// The URL can be shared with users or used in applications for direct download
console.log(downloadUrl);
Copy

Creates a pre-authenticated upload URL for a blob in Azure Blob Storage.

This method generates a Shared Access Signature (SAS) URL that allows for uploading a blob without needing the Azure Storage account credentials. The URL is valid for 10 minutes and can only be used for writing the specified blob.

Example

// Generate a pre-authenticated upload URL for a PDF file
const { UploadUrl } = await azureStorage.CreatePreAuthUploadUrl('documents/report.pdf');

// The URL can be used with tools like curl to upload the file
// curl -H "x-ms-blob-type: BlockBlob" --upload-file report.pdf --url "https://accountname.blob.core.windows.net/container/documents/report.pdf?sastoken"
console.log(UploadUrl);
Copy

Deletes a directory (virtual) and optionally its contents from Azure Blob Storage.

For non-recursive deletion, this method simply deletes the directory placeholder blob. For recursive deletion, it lists all blobs with the directory path as prefix and deletes them all, including the directory placeholder.

Example

// Delete an empty directory
const deleted = await azureStorage.DeleteDirectory('documents/temp/');

// Delete a directory and all its contents
const recursivelyDeleted = await azureStorage.DeleteDirectory('documents/old_projects/', true);
Copy

Deletes a blob from Azure Blob Storage.

This method attempts to delete the specified blob if it exists. It returns true if the blob was successfully deleted or if it didn't exist.

Example

// Delete a temporary file
const deleted = await azureStorage.DeleteObject('temp/report-draft.pdf');

if (deleted) {
  console.log('File successfully deleted');
} else {
  console.log('Failed to delete file');
}
Copy

Checks if a directory (virtual) exists in Azure Blob Storage.

Since Azure Blob Storage doesn't have a native directory concept, this method checks for either:

1. The existence of a directory placeholder blob (zero-byte blob with trailing slash)
2. The existence of any blobs with the directory path as a prefix

Example

// Check if a directory exists before trying to save files to it
const exists = await azureStorage.DirectoryExists('documents/reports/');

if (!exists) {
  console.log('Directory does not exist, creating it first');
  await azureStorage.CreateDirectory('documents/reports/');
}

// Now safe to use the directory
await azureStorage.PutObject('documents/reports/new-report.pdf', fileData);
Copy

Downloads a blob's content from Azure Blob Storage.

This method retrieves the full content of a blob and returns it as a Buffer for processing in memory.

Throws

Error if the blob doesn't exist or cannot be downloaded

Example

try {
  // For Azure Blob, objectId and fullPath are the same (both are the blob name)
  const content = await azureStorage.GetObject({ fullPath: 'documents/config.json' });
  // Or equivalently:
  const content2 = await azureStorage.GetObject({ objectId: 'documents/config.json' });

  // Parse the JSON content
  const config = JSON.parse(content.toString('utf8'));
  console.log('Configuration loaded:', config);
} catch (error) {
  console.error('Failed to download file:', error.message);
}
Copy

Retrieves metadata for a specific blob in Azure Blob Storage.

This method fetches the properties of a blob without downloading its content, which is more efficient for checking file attributes like size, content type, and last modified date.

Throws

Error if the blob doesn't exist or cannot be accessed

Example

try {
  // For Azure Blob, objectId and fullPath are the same (both are the blob name)
  const metadata = await azureStorage.GetObjectMetadata({ fullPath: 'documents/report.pdf' });
  // Or equivalently:
  const metadata2 = await azureStorage.GetObjectMetadata({ objectId: 'documents/report.pdf' });

  console.log(`File: ${metadata.name}`);
  console.log(`Size: ${metadata.size} bytes`);
  console.log(`Last modified: ${metadata.lastModified}`);
} catch (error) {
  console.error('File does not exist or cannot be accessed');
}
Copy

Lists blobs with the specified prefix in Azure Blob Storage.

This method returns a list of blobs (files) and virtual directories under the specified path prefix. Since Azure Blob Storage doesn't have actual directories, this method simulates directory structure by looking at blob names with common prefixes and using the delimiter to identify "directory" paths.

Example

// List all files and directories in the documents folder
const result = await azureStorage.ListObjects('documents/');

// Process files
for (const file of result.objects) {
  console.log(`File: ${file.name}, Size: ${file.size}, Type: ${file.contentType}`);
}

// Process subdirectories
for (const dir of result.prefixes) {
  console.log(`Directory: ${dir}`);
}
Copy

Moves a blob from one location to another within Azure Blob Storage.

Since Azure Blob Storage doesn't provide a native move operation, this method implements move as a copy followed by a delete operation. It first copies the blob to the new location, and if successful, deletes the blob from the original location.

Example

// Move a file from drafts to published folder
const success = await azureStorage.MoveObject(
  'drafts/report.docx',
  'published/final-report.docx'
);

if (success) {
  console.log('File successfully moved');
} else {
  console.log('Failed to move file');
}
Copy

Checks if a blob exists in Azure Blob Storage.

This method verifies the existence of a blob without downloading its content, which is efficient for validation purposes.

Example

// Check if a file exists before attempting to use it
const exists = await azureStorage.ObjectExists('documents/report.pdf');

if (exists) {
  console.log('File exists, proceeding with download');
  const content = await azureStorage.GetObject('documents/report.pdf');
  // Process the content...
} else {
  console.log('File does not exist');
}
Copy

Uploads data to a blob in Azure Blob Storage.

This method directly uploads a Buffer of data to a blob with the specified name. It's useful for server-side operations where you already have the data in memory.

Example

// Upload a text file
const content = Buffer.from('Hello, World!', 'utf8');
const uploaded = await azureStorage.PutObject(
  'documents/hello.txt',
  content,
  'text/plain',
  { author: 'John Doe', department: 'Engineering' }
);

if (uploaded) {
  console.log('File uploaded successfully');
} else {
  console.log('Failed to upload file');
}
Copy

Search is not supported by Azure Blob Storage. Blob Storage is an object storage service without built-in search capabilities.

To search Azure Blob Storage objects, consider:

• Using Azure Cognitive Search to index blob content
• Maintaining a separate search index (Azure Search, Elasticsearch, etc.)
• Using blob metadata and tags for filtering with ListObjects
• Using Azure Data Lake Analytics for complex queries

Throws

UnsupportedOperationError always