helper functions for flask url redirects

flask_url_helpers.py

from flask import request, url_for, redirect
from urllib.parse import urlencode, urlparse, urlunparse, parse_qsl


def get_referer_or_default(default='main.index'):
    """Returns the Referer URL if available, otherwise the default URL."""
    return request.headers.get("Referer") or url_for(default)

def redirect_to_referer_or_default(default='main.index'):
    """Redirects to the Referer URL if available, otherwise to the default URL."""
    return redirect(request.headers.get("Referer") or url_for(default))

def get_full_url(route, **kwargs):
    """Returns the full URL for a given route and additional query parameters."""
    return url_for(route, _external=True, **kwargs)

def get_query_param(param, default=None):
    """Returns the value of a query parameter from the request URL, or a default value."""
    return request.args.get(param, default)

def append_query_params(url, **kwargs):
    """Appends query parameters to an existing URL."""
    url_parts = list(urlparse(url))
    query = dict(parse_qsl(url_parts[4]))
    query.update(kwargs)
    url_parts[4] = urlencode(query)
    return urlunparse(url_parts)

def get_previous_url(default='main.index'):
    """Returns the previous URL or the default route."""
    return request.referrer or url_for(default)

def redirect_to_default(default='main.index'):
    """Redirects to the default route."""
    return redirect(url_for(default))