(PureBasic) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkRest.pb"
IncludeFile "CkUrl.pb"

Procedure ChilkatExample()

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

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

    bTls.i = 1
    port.i = 443
    bAutoReconnect.i = 1
    success.i = CkRest::ckConnect(rest,"chilkatsoft.com",port,bTls,bAutoReconnect)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; Send a POST to a URL that will respond with a 302 redirect..
    CkRest::ckAddQueryParam(rest,"firstName","John")
    CkRest::ckAddQueryParam(rest,"lastName","Doe")
    responseText.s = CkRest::ckFullRequestFormUrlEncoded(rest,"POST","/echoPost302.asp")
    If CkRest::ckLastMethodSuccess(rest) <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    statusCode.i = CkRest::ckResponseStatusCode(rest)

    ; Examine the response status code
    If statusCode < 300
        Debug "Not a redirect."
        Debug responseText
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    If statusCode > 399
        Debug "Error response: Status code = " + Str(statusCode)
        Debug responseText
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    Debug "Redirect status code = " + Str(statusCode)

    ; The response header will contain a Location field with the redirect URL, such as this:
    ; Location: http://www.chilkatsoft.com/echoPostFinal.asp

    ; The response status code determines how the client should behave.
    ; Here are some common possibilities:

    ; 301: Moved Permanently
    ; This and all future requests should be directed to the given URI.  (Keep the original HTTP method for the redirect.  In this case, the 
    ; original request was a POST, so we POST to the redirect URL.)

    ; 302: Found (aka Object Moved aka Moved Temporarily)
    ; This is the most popular redirect code, but also an example of industrial practice contradicting the standard. HTTP/1.0 specification (RFC 1945 ) required the client
    ; to perform a temporary redirect (the original describing phrase was Moved Temporarily), but popular browsers implemented it as a 303 See Other. Therefore, HTTP/1.1
    ; added status codes 303 and 307 to disambiguate between the two behaviors. However, the majority of Web applications and frameworks still use the 302 status code
    ; as if it were the 303.

    ; 303: See Other
    ; The response to the request can be found under another URI using a GET method. When received in response to a PUT, it should be assumed that the server has
    ; received the data and the redirect should be issued with a separate GET message.

    ; 307: Temporary Redirect
    ; In this occasion, the request should be repeated with another URI, but future requests can still use the original URI. In contrast to 303, the request method
    ; should not be changed when reissuing the original request. For instance, a POST request must be repeated using another POST request.

    Debug CkRest::ckResponseHeader(rest)

    redirectUrl.i = CkRest::ckRedirectUrl(rest)
    If CkRest::ckLastMethodSuccess(rest) = 0
        Debug "No Location header found for redirect."
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    ; Prep for the redirect..
    CkRest::ckClearAllParts(rest)

    ; Disconnect and re-connect.  
    ; (This can be skipped if both the host and SSL/TLS conditions are the same.)
    CkRest::ckDisconnect(rest,100)
    success = CkRest::ckConnect(rest,CkUrl::ckHost(redirectUrl),CkUrl::ckPort(redirectUrl),CkUrl::ckSsl(redirectUrl),bAutoReconnect)
    If success <> 1
        Debug CkRest::ckLastErrorText(rest)
        CkRest::ckDispose(rest)
        ProcedureReturn
    EndIf

    If (statusCode = 301) OR (statusCode = 307)
        ; Redirect using a POST, sending the same params to the new destination
        CkRest::ckAddQueryParam(rest,"firstName","John")
        CkRest::ckAddQueryParam(rest,"lastName","Doe")
        responseText = CkRest::ckFullRequestFormUrlEncoded(rest,"POST",CkUrl::ckPath(redirectUrl))
        If CkRest::ckLastMethodSuccess(rest) <> 1
            Debug CkRest::ckLastErrorText(rest)
            CkRest::ckDispose(rest)
            ProcedureReturn
        EndIf

    EndIf

    If (statusCode = 302) OR (statusCode = 303)
        ; Redirect using a GET, sending the query params found in the redirect URL.
        responseText = CkRest::ckFullRequestFormUrlEncoded(rest,"GET",CkUrl::ckPathWithQueryParams(redirectUrl))
        If CkRest::ckLastMethodSuccess(rest) <> 1
            Debug CkRest::ckLastErrorText(rest)
            CkRest::ckDispose(rest)
            ProcedureReturn
        EndIf

    EndIf

    ; Show the final status code and the response text.
    Debug "Final status code = " + Str(CkRest::ckResponseStatusCode(rest))

    Debug "Final response text (HTML, XML, JSON, or whatever..)"
    Debug responseText


    CkRest::ckDispose(rest)


    ProcedureReturn
EndProcedure