Prefix Property

A prefix used to restrict the results returned when listing files.

Syntax

 backblazeb2.getPrefix([callback])
 backblazeb2.setPrefix( prefix, [callback])

Default Value

""

Callback

The 'callback' parameter specifies a function which will be called when the operation completes (or an error is encountered). If the 'callback' parameter is not specified, then the method will block and will not return until the operation completes (or an error is encountered).

The callback for the getPrefix([callback]) method is defined as:

function(err, data){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'data' is the value returned by the method.

The callback for the setPrefix([callback]) method is defined as:

function(err){ }

'err' is the error that occurred. If there was no error, then 'err' is 'null'.

'err' has 2 properties which hold detailed information:

err.code
err.message

Remarks

This property, if non-empty, is used to restrict the values returned by ListFiles, ListFileVersions, or ListMultipartUploads to only the items whose names begin with the given prefix.

Note: If the currently-authenticated application key is restricted to a specific file name prefix (indicated by the AccountAllowedPrefix property being non-empty), then this property will automatically be set to that prefix if it is empty when one of the aforementioned methods is called.

File Hierarchy Traversal

By using the Delimiter and Prefix properties in tandem, applications can effectively "traverse" a virtual hierarchy of files (or file versions) as if it were a filesystem. For example, assume that files with the following names exist within a bucket:

• MyCompany
• MyCompany/Department1
• MyCompany/Department2
• MyCompany/Department2/EmployeeA
• MyCompany/Department2/EmployeeB

With Delimiter set to /, we can set Prefix to successively "deeper" values before calling ListFiles or ListFileVersions for the following effect:

This property is not available at design time.

Data Type

String