(Go) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

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

    rest := chilkat.NewRest()

    bTls := true
    port := 443
    bAutoReconnect := true
    success := rest.Connect("chilkatsoft.com",port,bTls,bAutoReconnect)
    if success != true {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        return
    }

    // Send a POST to a URL that will respond with a 302 redirect..
    rest.AddQueryParam("firstName","John")
    rest.AddQueryParam("lastName","Doe")
    responseText := rest.FullRequestFormUrlEncoded("POST","/echoPost302.asp")
    if rest.LastMethodSuccess() != true {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        return
    }

    statusCode := rest.ResponseStatusCode()

    // Examine the response status code
    if statusCode < 300 {
        fmt.Println("Not a redirect.")
        fmt.Println(*responseText)
        rest.DisposeRest()
        return
    }

    if statusCode > 399 {
        fmt.Println("Error response: Status code = ", statusCode)
        fmt.Println(*responseText)
        rest.DisposeRest()
        return
    }

    fmt.Println("Redirect status code = ", 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.

    fmt.Println(rest.ResponseHeader())

    redirectUrl := rest.RedirectUrl()
    if rest.LastMethodSuccess() == false {
        fmt.Println("No Location header found for redirect.")
        rest.DisposeRest()
        return
    }

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

    // Disconnect and re-connect.  
    // (This can be skipped if both the host and SSL/TLS conditions are the same.)
    rest.Disconnect(100)
    success = rest.Connect(redirectUrl.Host(),redirectUrl.Port(),redirectUrl.Ssl(),bAutoReconnect)
    if success != true {
        fmt.Println(rest.LastErrorText())
        rest.DisposeRest()
        return
    }

    if (statusCode == 301) || (statusCode == 307) {
        // Redirect using a POST, sending the same params to the new destination
        rest.AddQueryParam("firstName","John")
        rest.AddQueryParam("lastName","Doe")
        responseText = *rest.FullRequestFormUrlEncoded("POST",redirectUrl.Path())
        if rest.LastMethodSuccess() != true {
            fmt.Println(rest.LastErrorText())
            rest.DisposeRest()
            return
        }

    }

    if (statusCode == 302) || (statusCode == 303) {
        // Redirect using a GET, sending the query params found in the redirect URL.
        responseText = *rest.FullRequestFormUrlEncoded("GET",redirectUrl.PathWithQueryParams())
        if rest.LastMethodSuccess() != true {
            fmt.Println(rest.LastErrorText())
            rest.DisposeRest()
            return
        }

    }

    // Show the final status code and the response text.
    fmt.Println("Final status code = ", rest.ResponseStatusCode())

    fmt.Println("Final response text (HTML, XML, JSON, or whatever..)")
    fmt.Println(*responseText)

    rest.DisposeRest()