I have a Flask app with blueprints. I have a function that fetches a user’s profile image and returns it as a base64 string of text (too big to store in session). I use this in the html template navbar to show the user’s profile image.

I’m having difficulty sharing this image value across all html templates. I could not get context_processor method to work as it seemed to call the function immediately, versus when I call the function specifically after they’ve logged in.

My function:

def get_user_photo():
    # retrieves logged in user's profile picture
    try:
        sql = """
        SELECT picture_data FROM ps_image WHERE emplid = %s
        """

        swipe = Database()

        res = swipe.execute_select_ps(sql, params=[session["user_emplid"]])
        if "status" in res and res["status"] == "success":
            if "data" in res and len(res["data"]) > 0:
                images = res["data"]

                for img in images:
                    return img["picture_data"]
            else:
                logging.error(
                    f"No user photo found for {session['user_name']} [{session['user_emplid']}]: {res['status']}"
                )
                return "none"
        else:
            logging.error(
                f"Error getting user photo for {session['user_name']} [{session['user_emplid']}]: {res['status']}"
            )
            return "none"
    except Exception as e:
        logging.error("Error getting user photo for - {}".format(repr(e)))
        return "none"

And this is where I call that function after the user has logged in:

@page_blueprint.route("/", methods=["GET"])
def landing_page(url_params=None):
    # debug session data
    for k, v in session.items():
        logging.debug(f"-> {k}: {v}")

    if "logged_in" not in session:
        return redirect(url_for("page_blueprint.login_page"))

    user_photo = get_user_photo()
    
    #
    # how can i now pass user_photo to all blueprints/templates to use?
    #

    if "sso" in request.args and request.args.get("sso") != "":
        # Take user to main home page
        return render_template("/index.html", sso=request.args.get("sso"))
    else:
        # Take user to main home page
        return render_template("/index.html")