00:00:02 Let's create an interaction model.

00:00:05 Now what would an interaction even be?

00:00:08 Well, see, this is not something that you'll hear about in other YouTube videos or courses.

00:00:14 In this course, we'll go in a lot of depth to make sure that we develop a proper recommendation algorithm.

00:00:21 See, right here on the homepage, we can sort by newest, but we can also sort by recommended questions.

00:00:28 And I mean, how are you going to recommend the users some specific questions?

00:00:32 Sure, we can just ask them which languages they like at the start, but no.

00:00:36 In our case, later in the course, you'll develop a full-blown recommendation algorithm that tracks exactly what people are doing within the app.

00:00:46 Which types of questions they're upvoting, downvoting, which types of answers they're writing, which types of tags they're using,

00:00:52 and more.

00:00:53 So, let's develop it by creating a new model.

00:00:56 called interaction.model.ts.

00:01:00 We can start from the template model, and we can rename it to interaction.

00:01:05 Each interaction has to have a user who is doing that action.

00:01:10 So that's going to be of a type schema.types.objectid, which is a reference to a user, and it is required.

00:01:20 then we have to know what kind of action is it.

00:01:23 And that's going to be of a type string and required to true.

00:01:26 It can be upVote, downVote, view, askQuestions, or whatever you think of.

00:01:32 Next, we'll have an action ID.

00:01:34 So this will basically be a schema types object ID, which is going to be required to true.

00:01:40 And it can either be a question ID or the answer ID.

00:01:44 So it can either be a question ID, if they're viewing or answering on a specific question, It can maybe be an answer ID or even a user ID if they're viewing

00:01:53 specific user details.

00:01:54 So we know that that user is interested in tags that this user is writing about.

00:01:58 Finally, we're going to also have the action type, which is going to be of a type string.

00:02:05 required to true, and it'll be a special string of a type enum, which can either be question or answer.

00:02:14 Later on we can extend it, but for now I'm fine with tracking user actions on questions and answers of other people.

00:02:21 Let's define the interface.

00:02:23 It's going to have a user, which is of a types dot object ID.

00:02:28 It's going to have an action, which is going to be of a type string.

00:02:31 It's going to have an action ID, which is going to be of a types object ID.

00:02:36 And it's going to have an action type, which is going to be of a type string.

00:02:41 You could also put an enum here or just say that it could either be a question or an answer.

00:02:46 And that's it.

00:02:47 That's our interaction model.

00:02:49 Since it's the last model that we'll have in our database, we can also now delete the template model because we have no use for it anymore.

00:02:57 So take a look at this.

00:02:58 We have the account, answer, collection, interaction, question, tag, question, tag, user, and finally vote.

00:03:06 And all of these models together form the database architecture of our application.

00:03:13 Of course, as we use these different models, we'll dive deeper into how they interact, and we'll dive deeper into creating instances of these models based

00:03:22 on these schemas.

00:03:24 But I just want to let you know that with this database architecture in mind, you now actually have a better idea of how this entire application behaves.

00:03:33 That's why it's very important to be a full stack developer, so you get the full control of the database, the front end,

00:03:40 the back end, and in general, you just become so much better of a developer.

00:03:44 So we can say implement interaction model.

00:03:49 And with that, we'll very soon be able to put these models to use.

00:03:53 Great work.