URL to login with redirect URL after completion

Question

I have used ->isLoggedIn() method to detect whether a Magento user is logged in at that exact point. Now, I need to direct them to login IF they are not logged in, and specify a redirect URL upon success (which is not the same as the current URL - instead it will need a few extra parameters).

How do I do this? BTW we have Magento 1.4

I will be using:

Mage::getUrl(‘customer/account/login’);

to get the url, but it's how to redirect to a point that I don't know.

EDIT.. @Marius' post below was helpful and worked, but in some cases you may need to do a base64_encode yourself. essentially, whatever your login url is, make sure you add a trailing slash /, then add referer/nnnnnn where nnn is the base64_encode'd URL. To encode with JAVASCRIPT, I found this function, you can add it to your utilities:

https://stackoverflow.com/questions/246801/how-can-you-encode-a-string-to-base64-in-javascript to here: http://phpjs.org/functions/base64_encode/

base64_encode: function(data) {
    //  discuss at: http://phpjs.org/functions/base64_encode/
    // original by: Tyler Akins (http://rumkin.com)
    // improved by: Bayron Guevara
    // improved by: Thunder.m
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // improved by: Rafał Kukawski (http://kukawski.pl)
    // bugfixed by: Pellentesque Malesuada
    // example 1: base64_encode('Kevin van Zonneveld');
    // returns 1: 'S2V2aW4gdmFuIFpvbm5ldmVsZA=='
    // example 2: base64_encode('a');
    // returns 2: 'YQ=='
    var b64 = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';
    var o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
        ac = 0,
        enc = '',
        tmp_arr = [];
    if (!data) return data;
    do { // pack three octets into four hexets
        o1 = data.charCodeAt(i++);
        o2 = data.charCodeAt(i++);
        o3 = data.charCodeAt(i++);

        bits = o1 << 16 | o2 << 8 | o3;

        h1 = bits >> 18 & 0x3f;
        h2 = bits >> 12 & 0x3f;
        h3 = bits >> 6 & 0x3f;
        h4 = bits & 0x3f;

        // use hexets to index into b64, and append result to encoded string
        tmp_arr[ac++] = b64.charAt(h1) + b64.charAt(h2) + b64.charAt(h3) + b64.charAt(h4);
    } while (i < data.length);
    enc = tmp_arr.join('');
    var r = data.length % 3;
    return (r ? enc.slice(0, r - 3) : enc) + '==='.slice(r || 3);
}

Answer 1

Let's say you want to redirect after login to the url Mage::getUrl('something/goes/here').

Do this:

$redirectUrl = Mage::getUrl('something/goes/here');
$encodedUrl = Mage::helper('core')->urlEncode($redirectUrl);
$loginUrl = Mage::getUrl(
     'customer/account/login', 
      array(Mage_Customer_Helper_Data::REFERER_QUERY_PARAM_NAME => $encodedUrl)
);

Then redirect to $loginUrl.
Just make sure you have config setting System->Configuration->Customer Configuration->Login Options->Redirect Customer to Account Dashboard after Logging in set to No.