Details, details

findById() vs. findOne()

Mongoose provides specialized methods for single documents:

1. findById(id): Searches specifically for the _id field.
2. findOne({ field: value }): Searches for the first document matching a custom criteria.

When to use findById()

findById() is the workhorse of internal operations. It’s guaranteed to be unique and is the fastest way to retrieve a specific document.

Perfect for:

• Admin Dashboards: Editing a specific record (/admin/projects/65c123.../edit).
• Relationships: Looking up a user by their ID stored in a session.
• API Endpoints: Where the client already knows the ID.

However, for public-facing pages, IDs are clunky. That’s where findOne() shines.

Why Slugs?

IDs like 65c123... are ugly. URLs like /projects/my-cool-app (using slugs) are better for:

• SEO: Search engines can read the keywords.
• UX: Users can read the URL.

Watch out!! Slugs are fragile. Ensure they strictly contain lowercase letters, numbers, and hyphens. A space, a capital letter, or a special character (like ?, &, or /) can break our URL logic or even crash the router.

findOne() in action

data/projects.js

async getProjectBySlug(slug) {
  // We use findOne because we are searching by a custom field (slug)
  return await Project.findOne({ slug: slug, isActive: true });
}

Slugs in the Router

routers/projectRouter.js

We use a route parameter (:slug) to capture the project identifier from the URL.

router.get("/:slug", async (req, res) => {
  const { slug } = req.params;
  const project = await _projectOps.getProjectBySlug(slug);

  if (project) {
    res.render("project-detail", { project });
  } else {
    res.status(404).render("404");
  }
});

The Detail View

views/project-detail.ejs

<article>
  <h2><%= project.title %></h2>
  <p><%= project.description %></p>
  <a href="/projects">← Back to Gallery</a>
</article>

⏭ Next: Narrowing the Search

We can find all. We can find one. Now let’s find some.