detect_ie_browser.py

@current_app.before_request
def detect_ie_browser():
    """Redirect all IE visitors to a special page
    informing them to get a web browser.
    """
    # For this to work, the following conditions must be met:
    # 1. The visitor is using IE (doesn't matter what version)
    # 2. We must not be currently requesting a static file
    # (we still need page styles/resources to load)
    # 3. We don't need to be directly requesting the special page
    # (we create an endless redirect loop)
    if (
        request.user_agent.browser == "msie" and
        request.endpoint != "static" and
        request.endpoint != "special.unsupported_browser"
    ):
        return redirect(url_for("special.unsupported_browser"))