PureBasic

Get the Last-Modified Date Before HTTP Download

See more HTTP Examples

Demonstrates how to send a HEAD request to get the last-modified date of a file on a web server (without downloading the file). PureBasic

IncludeFile "CkHttpResponse.pb"
IncludeFile "CkHttp.pb"
IncludeFile "CkDateTime.pb"
IncludeFile "CkDtObj.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This example assumes the Chilkat API to have been previously unlocked.
    ; See Global Unlock Sample for sample code.

    http.i = CkHttp::ckCreate()
    If http.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    resp.i = CkHttpResponse::ckCreate()
    If resp.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkHttp::ckHttpNoBody(http,"HEAD","https://www.chilkatsoft.com/hamlet.xml",resp)
    If success = 0
        Debug CkHttp::ckLastErrorText(http)
        CkHttp::ckDispose(http)
        CkHttpResponse::ckDispose(resp)
        ProcedureReturn
    EndIf

    ; Examine the response header.
    Debug CkHttpResponse::ckHeader(resp)

    ; Here is a sample response header:

    ; 	Content-Length: 279658
    ; 	Content-Type: text/xml
    ; 	Last-Modified: Thu, 12 May 2016 15:14:08 GMT
    ; 	Accept-Ranges: bytes
    ; 	ETag: "c1cd8bee60acd11:0"
    ; 	Server: Microsoft-IIS/8.5
    ; 	X-Powered-By: ASP.NET
    ; 	X-Powered-By-Plesk: PleskWin
    ; 	Date: Thu, 25 Jul 2019 16:40:54 GMT

    ; Get the Last-Modified header.
    lastModStr.s = CkHttpResponse::ckGetHeaderField(resp,"Last-Modified")
    ; If the header exists...
    If CkHttpResponse::ckLastMethodSuccess(resp) = 1
        ; Parse the RFC822 format date/time string
        ckdt.i = CkDateTime::ckCreate()
        If ckdt.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        CkDateTime::ckSetFromRfc822(ckdt,lastModStr)

        ; If we want to access individual date/time parts (in the local timezone)
        dt.i = CkDtObj::ckCreate()
        If dt.i = 0
            Debug "Failed to create object."
            ProcedureReturn
        EndIf

        CkDateTime::ckToDtObj(ckdt,1,dt)

        Debug "day/month/year = " + Str(CkDtObj::ckDay(dt)) + "/" + Str(CkDtObj::ckMonth(dt)) + "/" + Str(CkDtObj::ckYear(dt))
    EndIf



    CkHttp::ckDispose(http)
    CkHttpResponse::ckDispose(resp)
    CkDateTime::ckDispose(ckdt)
    CkDtObj::ckDispose(dt)


    ProcedureReturn
EndProcedure