VB.NET

Retrieve Metadata from a Gzip File

See more Gzip Examples

This example demonstrates how to use the GetGzipInfo method to retrieve metadata embedded within a Gzip file.

The method reads the Gzip header and extracts any available metadata, including the embedded filename, comment, and optional extra data. The extracted information is returned in a JsonObject.

Because these fields are optional, the example checks for the existence of each JSON member using HasMember before retrieving its value. This avoids attempting to access values that may not be present.

VB.NET

Dim success As Boolean = False

' This example demonstrates how to retrieve metadata embedded in a Gzip file.

Dim gzip As New Chilkat.Gzip
Dim json As New Chilkat.JsonObject

' The Gzip file to examine:
Dim gzPath As String = "example.txt.gz"

' Get the metadata information:
success = gzip.GetGzipInfo(gzPath,json)
If (success = False) Then
    Debug.WriteLine(gzip.LastErrorText)
    Exit Sub
End If


' Output the JSON containing metadata:
Debug.WriteLine("Gzip metadata JSON:")
Debug.WriteLine(json.Emit())

' Access individual fields only if they exist:

If (json.HasMember("filename") = True) Then
    Dim filename As String = json.StringOf("filename")
    Debug.WriteLine("Filename: " & filename)
End If


If (json.HasMember("comment") = True) Then
    Dim comment As String = json.StringOf("comment")
    Debug.WriteLine("Comment: " & comment)
End If


If (json.HasMember("extraData") = True) Then
    Dim extraData As String = json.StringOf("extraData")
    Debug.WriteLine("ExtraData (Base64): " & extraData)
End If