DataFlex

REST Follow Redirects

See more REST Examples

Demonstrates how to follow a 302/303 redirect response. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoRest
    Boolean iBTls
    Integer iPort
    Boolean iBAutoReconnect
    String sResponseText
    Integer iStatusCode
    String sUrlStr
    Handle hoRedirectUrl
    String sTemp1
    Integer iTemp1
    Boolean bTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatRest)) To hoRest
    If (Not(IsComObjectCreated(hoRest))) Begin
        Send CreateComObject of hoRest
    End

    Move True To iBTls
    Move 443 To iPort
    Move True To iBAutoReconnect
    Get ComConnect Of hoRest "chilkatsoft.com" iPort iBTls iBAutoReconnect To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Send a POST to a URL that will respond with a 302 redirect..
    Get ComAddQueryParam Of hoRest "firstName" "John" To iSuccess
    Get ComAddQueryParam Of hoRest "lastName" "Doe" To iSuccess
    Get ComFullRequestFormUrlEncoded Of hoRest "POST" "/echoPost302.asp" To sResponseText
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComResponseStatusCode Of hoRest To iStatusCode

    // Examine the response status code
    If (iStatusCode < 300) Begin
        Showln "Not a redirect."
        Showln sResponseText
        Procedure_Return
    End

    If (iStatusCode > 399) Begin
        Showln "Error response: Status code = " iStatusCode
        Showln sResponseText
        Procedure_Return
    End

    Showln "Redirect status code = " iStatusCode

    // 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.

    Get ComResponseHeader Of hoRest To sTemp1
    Showln sTemp1

    // Get the redirect URL
    Get ComLastRedirectUrl Of hoRest To sUrlStr
    Get ComLastMethodSuccess Of hoRest To bTemp1
    If (bTemp1 = False) Begin
        Showln "No Location header found for redirect."
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatUrl)) To hoRedirectUrl
    If (Not(IsComObjectCreated(hoRedirectUrl))) Begin
        Send CreateComObject of hoRedirectUrl
    End
    Get ComParseUrl Of hoRedirectUrl sUrlStr To iSuccess

    // Prep for the redirect..
    Get ComClearAllParts Of hoRest To iSuccess

    // Disconnect and re-connect.  
    // (This can be skipped if both the host and SSL/TLS conditions are the same.)
    Get ComDisconnect Of hoRest 100 To iSuccess
    Get ComHost Of hoRedirectUrl To sTemp1
    Get ComPort Of hoRedirectUrl To iTemp1
    Get ComSsl Of hoRedirectUrl To bTemp1
    Get ComConnect Of hoRest sTemp1 iTemp1 bTemp1 iBAutoReconnect To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoRest To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    If ((iStatusCode = 301) Or (iStatusCode = 307)) Begin
        // Redirect using a POST, sending the same params to the new destination
        Get ComAddQueryParam Of hoRest "firstName" "John" To iSuccess
        Get ComAddQueryParam Of hoRest "lastName" "Doe" To iSuccess
        Get ComPath Of hoRedirectUrl To sTemp1
        Get ComFullRequestFormUrlEncoded Of hoRest "POST" sTemp1 To sResponseText
        Get ComLastMethodSuccess Of hoRest To bTemp1
        If (bTemp1 = False) Begin
            Get ComLastErrorText Of hoRest To sTemp1
            Showln sTemp1
            Procedure_Return
        End

    End

    If ((iStatusCode = 302) Or (iStatusCode = 303)) Begin
        // Redirect using a GET, sending the query params found in the redirect URL.
        Get ComPathWithQueryParams Of hoRedirectUrl To sTemp1
        Get ComFullRequestFormUrlEncoded Of hoRest "GET" sTemp1 To sResponseText
        Get ComLastMethodSuccess Of hoRest To bTemp1
        If (bTemp1 = False) Begin
            Get ComLastErrorText Of hoRest To sTemp1
            Showln sTemp1
            Procedure_Return
        End

    End

    // Show the final status code and the response text.
    Get ComResponseStatusCode Of hoRest To iTemp1
    Showln "Final status code = " iTemp1

    Showln "Final response text (HTML, XML, JSON, or whatever..)"
    Showln sResponseText


End_Procedure