How can I use params to dynamically create links

Question

I am wondering if anyone has any suggestion on how to get around this error i am getting. I am using params to dynamically create links, however when i post a new blog post i am getting a casting error since it tries to create a new link before the blog has generated an ID. My code is as follows

router.get("/blog/:id", ensureAuthenticated, (req, res) => {
    let id = req.params.id;
    console.log(`id is ${id}`)
    Blog.findOne({_id: id})
        .then((result) => {
            console.log(`result: ${result}`)
            res.render("viewPost", {
                post: result,
                user: req.user,
            });
        })
        .catch((error) => {
            console.log(error)
        })
});

router.post("/blog-new", (req, res) => {
    const blog = new Blog({
        title: req.body.title,
        snippet: req.body.snippet,
        body: req.body.blog,
    })
    blog.save()
        .then((result) => {
            res.redirect("blog/posted");
        })
        .catch((error) => {
            console.log(error);
        })
})