(Visual FoxPro) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loRest
LOCAL lnBTls
LOCAL lnPort
LOCAL lnBAutoReconnect
LOCAL lnSuccess
LOCAL lcResponseText
LOCAL lnStatusCode
LOCAL loRedirectUrl

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

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Rest')
loRest = CreateObject('Chilkat.Rest')

lnBTls = 1
lnPort = 443
lnBAutoReconnect = 1
lnSuccess = loRest.Connect("chilkatsoft.com",lnPort,lnBTls,lnBAutoReconnect)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    CANCEL
ENDIF

* Send a POST to a URL that will respond with a 302 redirect..
loRest.AddQueryParam("firstName","John")
loRest.AddQueryParam("lastName","Doe")
lcResponseText = loRest.FullRequestFormUrlEncoded("POST","/echoPost302.asp")
IF (loRest.LastMethodSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    CANCEL
ENDIF

lnStatusCode = loRest.ResponseStatusCode

* Examine the response status code
IF (lnStatusCode < 300) THEN
    ? "Not a redirect."
    ? lcResponseText
    RELEASE loRest
    CANCEL
ENDIF

IF (lnStatusCode > 399) THEN
    ? "Error response: Status code = " + STR(lnStatusCode)
    ? lcResponseText
    RELEASE loRest
    CANCEL
ENDIF

? "Redirect status code = " + STR(lnStatusCode)

* 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.

? loRest.ResponseHeader

loRedirectUrl = loRest.RedirectUrl()
IF (loRest.LastMethodSuccess = 0) THEN
    ? "No Location header found for redirect."
    RELEASE loRest
    CANCEL
ENDIF

* Prep for the redirect..
loRest.ClearAllParts()

* Disconnect and re-connect.  
* (This can be skipped if both the host and SSL/TLS conditions are the same.)
loRest.Disconnect(100)
lnSuccess = loRest.Connect(loRedirectUrl.Host,loRedirectUrl.Port,loRedirectUrl.Ssl,lnBAutoReconnect)
IF (lnSuccess <> 1) THEN
    ? loRest.LastErrorText
    RELEASE loRest
    CANCEL
ENDIF

IF ((lnStatusCode = 301) OR (lnStatusCode = 307)) THEN
    * Redirect using a POST, sending the same params to the new destination
    loRest.AddQueryParam("firstName","John")
    loRest.AddQueryParam("lastName","Doe")
    lcResponseText = loRest.FullRequestFormUrlEncoded("POST",loRedirectUrl.Path)
    IF (loRest.LastMethodSuccess <> 1) THEN
        ? loRest.LastErrorText
        RELEASE loRest
        CANCEL
    ENDIF

ENDIF

IF ((lnStatusCode = 302) OR (lnStatusCode = 303)) THEN
    * Redirect using a GET, sending the query params found in the redirect URL.
    lcResponseText = loRest.FullRequestFormUrlEncoded("GET",loRedirectUrl.PathWithQueryParams)
    IF (loRest.LastMethodSuccess <> 1) THEN
        ? loRest.LastErrorText
        RELEASE loRest
        CANCEL
    ENDIF

ENDIF

* Show the final status code and the response text.
? "Final status code = " + STR(loRest.ResponseStatusCode)

? "Final response text (HTML, XML, JSON, or whatever..)"
? lcResponseText

RELEASE loRest