Xbase++ Requires Chilkat v11.5.0+

Retrieve Metadata from Gzip Data in Memory (BinData)

This example demonstrates how to use the GetGzipInfoBd method to retrieve metadata from Gzip data stored in memory within a BinData object.

The Gzip data is first loaded into the BinData instance. The GetGzipInfoBd method then extracts any available metadata from the Gzip header, including the embedded filename, comment, and optional extra data.

The metadata 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.

Xbase++

LOCAL nSuccess
LOCAL oGzip
LOCAL oBd
LOCAL oJson
LOCAL cFilename
LOCAL cComment
LOCAL cExtraData

nSuccess := 0

//  This example demonstrates how to retrieve metadata from Gzip data
//  stored in a BinData object.

oGzip := CreateObject("Chilkat.Gzip")
oBd := CreateObject("Chilkat.BinData")
oJson := CreateObject("Chilkat.JsonObject")

//  Load a Gzip file into BinData:
nSuccess := oBd:LoadFile("example.txt.gz")
IF (nSuccess == 0)
    ? oBd:LastErrorText
    oGzip:destroy()
    oBd:destroy()
    oJson:destroy()
    RETURN
ENDIF

//  Get the metadata information from the in-memory Gzip data:
nSuccess := oGzip:GetGzipInfoBd(oBd, oJson)
IF (nSuccess == 0)
    ? oGzip:LastErrorText
    oGzip:destroy()
    oBd:destroy()
    oJson:destroy()
    RETURN
ENDIF

//  Output the JSON containing metadata:
? "Gzip metadata JSON:"
? oJson:Emit()

//  Access individual fields only if they exist:

IF (oJson:HasMember("filename") == 1)
    cFilename := oJson:StringOf("filename")
    ? "Filename: " + cFilename
ENDIF

IF (oJson:HasMember("comment") == 1)
    cComment := oJson:StringOf("comment")
    ? "Comment: " + cComment
ENDIF

IF (oJson:HasMember("extraData") == 1)
    cExtraData := oJson:StringOf("extraData")
    ? "ExtraData (Base64): " + cExtraData
ENDIF

oGzip:destroy()
oBd:destroy()
oJson:destroy()