(JavaScript) REST Follow Redirects

Demonstrates how to follow a 302/303 redirect response.

Note: This example requires Chilkat v11.0.0 or greater.

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

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

var rest = new CkRest();

var bTls = true;
var port = 443;
var bAutoReconnect = true;
success = rest.Connect("chilkatsoft.com",port,bTls,bAutoReconnect);
if (success == false) {
    console.log(rest.LastErrorText);
    return;
}

// Send a POST to a URL that will respond with a 302 redirect..
rest.AddQueryParam("firstName","John");
rest.AddQueryParam("lastName","Doe");
var responseText = rest.FullRequestFormUrlEncoded("POST","/echoPost302.asp");
if (rest.LastMethodSuccess == false) {
    console.log(rest.LastErrorText);
    return;
}

var statusCode = rest.ResponseStatusCode;

// Examine the response status code
if (statusCode < 300) {
    console.log("Not a redirect.");
    console.log(responseText);
    return;
}

if (statusCode > 399) {
    console.log("Error response: Status code = " + statusCode);
    console.log(responseText);
    return;
}

console.log("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.

console.log(rest.ResponseHeader);

// Get the redirect URL
var urlStr = rest.LastRedirectUrl;
if (rest.LastMethodSuccess == false) {
    console.log("No Location header found for redirect.");
    return;
}

var redirectUrl = new CkUrl();
redirectUrl.ParseUrl(urlStr);

// 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 == false) {
    console.log(rest.LastErrorText);
    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 == false) {
        console.log(rest.LastErrorText);
        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 == false) {
        console.log(rest.LastErrorText);
        return;
    }

}

// Show the final status code and the response text.
console.log("Final status code = " + rest.ResponseStatusCode);

console.log("Final response text (HTML, XML, JSON, or whatever..)");
console.log(responseText);