Debugging PhantomJS webpage.open failures

问题:

In PhantomJS, webpage.open takes a callback with a status parameter that's set to 'success' or 'fail'. According to the docs, it wll be "'success' if no network errors occurred, otherwise 'fail'." Is there a way to see the underlying network error that caused the failure?

The url I'm trying to load works fine when I put it in my browser, and when I take a screenshot after getting the 'fail' message I see the page that I was on before I called webpage.open (so I can't just ignore the fail). I'm using Phantom for testing, so ideally I'd like a robust way of easily getting a helpful error messsage when webpage.open fails (or better yet have it never fail!)

回答1:

Found this post which explains how to set up callbacks to get at the underlying reason for the failure: http://newspaint.wordpress.com/2013/04/25/getting-to-the-bottom-of-why-a-phantomjs-page-load-fails/

Based on the that page, you could print out errors as follows:

page.onResourceError = function(resourceError) {
    console.error(resourceError.url + ': ' + resourceError.errorString);
};

The page goes on to show an example of detailed logging for phantoms

page.onResourceRequested = function (request) {
    system.stderr.writeLine('= onResourceRequested()');
    system.stderr.writeLine('  request: ' + JSON.stringify(request, undefined, 4));
};

page.onResourceReceived = function(response) {
    system.stderr.writeLine('= onResourceReceived()' );
    system.stderr.writeLine('  id: ' + response.id + ', stage: "' + response.stage + '", response: ' + JSON.stringify(response));
};

page.onLoadStarted = function() {
    system.stderr.writeLine('= onLoadStarted()');
    var currentUrl = page.evaluate(function() {
        return window.location.href;
    });
    system.stderr.writeLine('  leaving url: ' + currentUrl);
};

page.onLoadFinished = function(status) {
    system.stderr.writeLine('= onLoadFinished()');
    system.stderr.writeLine('  status: ' + status);
};

page.onNavigationRequested = function(url, type, willNavigate, main) {
    system.stderr.writeLine('= onNavigationRequested');
    system.stderr.writeLine('  destination_url: ' + url);
    system.stderr.writeLine('  type (cause): ' + type);
    system.stderr.writeLine('  will navigate: ' + willNavigate);
    system.stderr.writeLine('  from page\'s main frame: ' + main);
};

page.onResourceError = function(resourceError) {
    system.stderr.writeLine('= onResourceError()');
    system.stderr.writeLine('  - unable to load url: "' + resourceError.url + '"');
    system.stderr.writeLine('  - error code: ' + resourceError.errorCode + ', description: ' + resourceError.errorString );
};

page.onError = function(msg, trace) {
    system.stderr.writeLine('= onError()');
    var msgStack = ['  ERROR: ' + msg];
    if (trace) {
        msgStack.push('  TRACE:');
        trace.forEach(function(t) {
            msgStack.push('    -> ' + t.file + ': ' + t.line + (t.function ? ' (in function "' + t.function + '")' : ''));
        });
    }
    system.stderr.writeLine(msgStack.join('\n'));
};