(Xojo Plugin) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

Chilkat Xojo Plugin Download Xojo Plugin for Windows, Linux, Mac OS X, and ARM, ARM64

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

Dim rest As New Chilkat.Rest

Dim bTls As Boolean
bTls = True
Dim port As Int32
port = 443
Dim bAutoReconnect As Boolean
bAutoReconnect = True
Dim success As Boolean
success = rest.Connect("chilkatsoft.com",port,bTls,bAutoReconnect)
If (success <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

// Send a POST to a URL that will respond with a 302 redirect..
success = rest.AddQueryParam("firstName","John")
success = rest.AddQueryParam("lastName","Doe")
Dim responseText As String
responseText = rest.FullRequestFormUrlEncoded("POST","/echoPost302.asp")
If (rest.LastMethodSuccess <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

Dim statusCode As Int32
statusCode = rest.ResponseStatusCode

// Examine the response status code
If (statusCode < 300) Then
    System.DebugLog("Not a redirect.")
    System.DebugLog(responseText)
    Return
End If

If (statusCode > 399) Then
    System.DebugLog("Error response: Status code = " + Str(statusCode))
    System.DebugLog(responseText)
    Return
End If

System.DebugLog("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.

System.DebugLog(rest.ResponseHeader)

Dim redirectUrl As Chilkat.Url
redirectUrl = rest.RedirectUrl()
If (rest.LastMethodSuccess = False) Then
    System.DebugLog("No Location header found for redirect.")
    Return
End If

// Prep for the redirect..
success = rest.ClearAllParts()

// Disconnect and re-connect.  
// (This can be skipped if both the host and SSL/TLS conditions are the same.)
success = rest.Disconnect(100)
success = rest.Connect(redirectUrl.Host,redirectUrl.Port,redirectUrl.Ssl,bAutoReconnect)
If (success <> True) Then
    System.DebugLog(rest.LastErrorText)
    Return
End If

If ((statusCode = 301) Or (statusCode = 307)) Then
    // Redirect using a POST, sending the same params to the new destination
    success = rest.AddQueryParam("firstName","John")
    success = rest.AddQueryParam("lastName","Doe")
    responseText = rest.FullRequestFormUrlEncoded("POST",redirectUrl.Path)
    If (rest.LastMethodSuccess <> True) Then
        System.DebugLog(rest.LastErrorText)
        Return
    End If

End If

If ((statusCode = 302) Or (statusCode = 303)) Then
    // Redirect using a GET, sending the query params found in the redirect URL.
    responseText = rest.FullRequestFormUrlEncoded("GET",redirectUrl.PathWithQueryParams)
    If (rest.LastMethodSuccess <> True) Then
        System.DebugLog(rest.LastErrorText)
        Return
    End If

End If

// Show the final status code and the response text.
System.DebugLog("Final status code = " + Str(rest.ResponseStatusCode))

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