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Now, in this course section,

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as I mentioned before,

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we're going to build a basic blog website,

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which will look like this,

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and which will allow us to browse blog posts,

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to add new blog posts,

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where we also have a dropdown with predefined authors

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that can be assigned to blog posts.

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and we're then, of course, also going to be able

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to view individual blog posts.

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And we'll, of course, also be able to add

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or delete blog posts.

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So we've got all these CRUD operations

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incorporated into this website.

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So that's what we're going to build.

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And this slide here is actually from the MySQL

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and NodeJS course section.

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We're going to build the same thing with NoSQL

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and MongoDB here,

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but there will be an important difference

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when it comes to the steps we're going to go through.

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With MySQL, we planned and designed

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our databases and tables.

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And we then created those database tables.

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And then we added some initial data.

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With NoSQL and MongoDB, of course,

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the step where we create databases and tables

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will be skipped.

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And we're also going to plan our database layout

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a little bit differently.

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We're mostly going to think

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about the queries we will be running.

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And then decide which collections we want,

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and how the documents should look like.

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And then we're still going to add some initial data,

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but not through some graphical user interface,

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but instead with help of the MongoDB shell,

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which we also used before, in the course already.

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Now, last but not least, then of course,

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as the most important part of this course section,

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you are then going to see how you can also connect

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and talk to that database from inside

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the NodeJS/Express backend code.

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Now, therefore let's dive right in

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and plan our database structure.

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And as you learned, when it comes to planning

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your database structure, and which collections you want,

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and how your documents should look like,

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in a NoSQL database, then you actually wanna start

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by thinking about the queries you'll be running.

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Are you going to do a lot of writing to the database?

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A lot of inserting or a lot of reading?

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For a lot of websites, it's more reading than writing,

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but of course that's not necessarily true for every website.

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And then once you made that decision,

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it, of course, is important to understand

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which kind of data are you going to write or read.

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And you then want to create collections

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that actually minimize the effort of running

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those write or read queries.

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Now, in this website, which we're going to build here,

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we are building a blog.

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And whilst of course, we do have capabilities for adding

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and deleting and updating blog posts.

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There probably won't be

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multiple blog posts added every minute.

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So there won't be a lot of writing,

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only some occasional write operations.

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On the apprehend, it is, of course, fair to assume

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that for a blog, there will be a lot of data fetching.

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We will hopefully have a lot of visitors

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who view this starting page with all the blog posts

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or who then also viewed the individual blog posts.

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So we will often fetch all the blog posts

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or single blog posts, which we identify by ID.

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And therefore, we want to plan our collections for that.

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Now, of course, it makes sense that therefore

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create a collection that holds all our posts.

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That we create a posts collection,

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which then stores our post documents.

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So every blog post is a standalone document

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in that post's collection.

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And then every document in this post collection

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should have some unique identifier, this unique ID,

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which thankfully will be created automatically

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by MongoDB for us.

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And then of course, it's up to you how a blog post

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should look for you.

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For me, it will have a title,

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so the main title of the blog post.

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Then a short summary text,

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which I show on the page where we list all the blog posts.

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Then the detailed full text body

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that belongs to every blog post,

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which you can see if you visit the detailed page

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of a single blog post.

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And of course, I also want to have a date snapshot,

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which basically tells me when this blog post was created.

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And that will also be part of the data

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we show to the user in the end.

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And then there's a never key element

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and never a key piece of data

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that's attached to every blog post.

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And that should be information about the author

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of the blog post.

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Now, here's something important though,

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when it comes to this author,

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it's not just attached to the blog post,

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but we also need to be able to get

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a list of available authors when we add a new blog post,

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because there, I want to have a dropdown

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where you can choose from a predefined list of authors.

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So that you can't come up with arbitrary names

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or introduce typos when typing the author name.

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But that instead, this is a fixed list of predefined values

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and those values should be coming from the database as well.

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So that, again, you can't introduce errors

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by mistyping or anything like that.

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And therefore we will actually also have

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a second collection of authors.

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And there, I wanna have a unique identifier per author.

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And then let's say the name

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and email address of each author.

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And we will actually pre-populate

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this author's collection ahead of time.

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Our website won't have a section or a site

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where you can add new authors.

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Though, of course, as an extra bonus task,

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you could try to add such a site to it.

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But instead here, we will just assume

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that some global administrator

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is administrating the list of authors.

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And therefore, that will be some data,

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which we actually add through the MongoDB shell,

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and which we then can use in the website

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for populating this dropdown,

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and for connecting blog posts to authors.

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But speaking off that,

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of course, a blog post should be affiliated with an author.

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And therefore we will store the idea of an author

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for a given blog post.

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But I'll not just do that.

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In the MySQL world, we would just have stored the ID

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and then we would have joined the data together

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when we need the combined data.

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When we also need the name of the author.

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But here, for example, when I show a list of all blog posts,

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I do wanna show that author name here.

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I don't need to email address here.

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But it would be a bit annoying if we have to always join

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the two collections here

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for displaying a list of blog posts.

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If we would have to run two different query stale for.

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Remember that our goal always is to reduce the amount

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of queries and we would not achieve this here.

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Therefore, I will actually also store the author name

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in my blog posts collection.

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So the ID, and then also the name of and affiliated

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of a related author for a given blog post document.

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Of course, the name therefore, will be duplicated.

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It's in the different blog post documents,

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and it's in the authors collection documents

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in one of the documents there.

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But that shouldn't be a huge issue.

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It would be a huge issue if the name would change

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all the time, because then we have to change it

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in both the authors collection

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and possibly in a lot of documents in the posts collection.

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But names typically don't change that often.

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So this kind of duplication won't be a problem.

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We could also duplicate the email address,

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so that we never have to run an unnecessary second query

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to get this data.

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And we might implement this for all this course section,

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but of course, email addresses could change

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more frequently than names.

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So there, it really comes down to request

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to whoever that is data that you expect to change a lot.

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In which case, duplicating it would be bad

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because when it changes,

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you will have to attach a lot of documents,

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which is bad for performance

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and is a lot of work you have to do.

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If you don't expect email addresses to change a lot,

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you could also duplicated that

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into your blog posts documents,

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so that you actually never have to run queries reaching out

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to two different collections at the same time

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to get some merged data.

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Because unlike with MySQL,

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there is no join operation that you could run

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on the database level,

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instead, for NoSQL databases like MongoDB.

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If you want to join data from multiple collections,

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you'll have to do it manually.

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So I'll come back to that when we have the problem later on,

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but that's the general structure I plan on implementing.

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And throughout this course section,

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you'll see how that works,

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which potential challenges we face,

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and how we can run queries efficiently

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with that plan layout here.

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Now, with all of that,

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it's therefore time to leave the theory

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and dive into our project.

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And get started by adding or by connecting to MongoDB.

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And then also get started with adding blog posts and so on.