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So let's go from drawing to database action. I'll go to my blog database

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and there I said when I want to use two collections, let's start with the users collection, there

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let's say I insert

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many users, we get multiple authors on our blog.

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Now insertMany takes an array of documents where each document is one element we insert into this

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collection, a user here can have a name, Max Schwarzmuller, can have an age,

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29 and let's say an e-mail address, max@test.com which is not my real address.

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I also have a second author, Manuel Lorenz, age 30 and also an e-mail here, manu@test.com, if I hit enter,

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these two elements get inserted 

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and obviously we can now pretty print them,

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this is the data in our users collection.

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Now let's go to our posts collection,

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so posts, there

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I want to insert one post let's say, obviously we could insert multiple posts.

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Now one post can have a title,

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my first post, a post can also have some text which holds the actual content,

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this is my first post,

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I hope you like it

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and this could be a very long text

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as you learned, the text type is able to store very long text.

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We might also have some tags here and that could be an array of strings like new tech,

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whatever your tags are and now we come to the relations.

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Now my relation here is that this post is written by a user,

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let's name it creator

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and this could be a list if you have multiple authors in your application,

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let's say in this application and that is totally up to you of course,

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we only have one author per host.

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So my creator or author, however you want to name it here should be one of my users

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and let's say this was written by Manuel, so I'll copy that objectId,

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we could match it by any key of course but we should insure it's unique

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and the objectId isn't sure to be unique and I'll therefore set this as a value for creator.

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Now we also might have comments here and let's say we get a couple of comments there and each comment

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then is another document,

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so here I got a list of documents where I have some text,

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I like this post and as another key here,

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I don't just have the text but also the author of this comment

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and that again would be the ID of a user,

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so let's grab Max here maybe, grab that objectId here and insert this

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as the author.

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So here again,

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I'm also using not an embedded user for the same reason why I'm not using it on a post, I'm not using

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it on a comment either

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instead here, I also use a reference.

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Let's hit enter,

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this worked and let's have a look at our post,

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this is how it looks like.

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And this post has the fields

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I sketched out and most importantly, we have a reference relation to the person who created the post

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but we got an embedded document or even multiple documents for the comments where each comment in turn

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also has a reference relation to the author.

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This is how our blog could look like in code,

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so in the database and I also explained why I would structure it like this and this example together with the

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previous lectures hopefully gets you into the right mental model on how to think about this and hopefully

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helps you with your next projects to structure your data and your relations in a way that makes sense

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for your application to your size of data,

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the amount of data,

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the frequency with which you change it and your overall structure or relation that is imposed on to you

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by your application.