00:00:02 Let's create a model for our tags.

00:00:05 Tag is a collection that helps us categorize different questions.

00:00:09 That means that each tag can contain multiple questions, but we also want to be able to filter through tags themselves, not caring about the questions

00:00:17 within them, like in this page right here.

00:00:19 So in this case, we'll do a great optimization for querying your database.

00:00:24 If you take a look at the database structure, you can notice that we're going to have two different tag models.

00:00:30 One will be for the tag itself, which simply has its name, the number of questions it has, and then we'll have a separate one where we can pull all the

00:00:41 questions related to that tag.

00:00:43 I mean, now that I mention it, it makes complete sense because you have to ask yourself in which scenario will you have to query that collection.

00:00:51 We're querying the tags in the tags page where you want to see all the different tags But you don't necessarily need to see 23,000 questions within them.

00:01:01 You just want to see this single number.

00:01:03 So this is a perfect way to do that.

00:01:05 You can simply query the tags collection to see their names and the number of questions.

00:01:10 But then, when you want to extract the actual questions belonging to that tag, you can use the second model.

00:01:16 And I'm using the terms model and collection and even schema interchangeably.

00:01:21 because they're all pointing to the same thing, a collection or a model off of which we can create a document or an instance of that model.

00:01:30 Hopefully that makes sense.

00:01:32 So let's go ahead and create a new file called tag.model.ts.

00:01:38 Let's start from the template model and I will once again rename it to simply say tag.

00:01:46 There we go.

00:01:47 Make sure to do the same.

00:01:48 And if you're not doing these quick tricks, as I am doing with auto change of the specific text, then be very careful for all of the things to have changed.

00:01:58 The tag, the tag schema, the types and more, because if you're not careful, that can cause issues.

00:02:05 Oh, such as the issue that I have caused right here.

00:02:08 Check this out.

00:02:09 It didn't actually change the account because I forgot to change that from the last time.

00:02:14 So thankfully I have caught myself in the error.

00:02:17 Let's actually go over these last couple of models to make sure that we don't have an issue.

00:02:23 Here, I changed it to account.

00:02:25 That's good.

00:02:27 in the answer.

00:02:28 Oh, it says account.

00:02:29 This should say answer right here.

00:02:31 So please be careful that all of these properties are properly typed out.

00:02:36 I'm actually glad the error happened to me.

00:02:38 So you can know that errors do happen, but this is going to cause significant issues later on in our database if we don't fix them on time.

00:02:46 And for the question, it says account, it needs to say question.

00:02:52 Oh, take a look at this.

00:02:53 It did not auto change this.

00:02:55 This should also say question.

00:02:58 Okay.

00:02:58 I think we're good now.

00:03:00 No other instances of answer.

00:03:03 What about the answer itself?

00:03:06 It also says models.account.

00:03:08 It should say answer.

00:03:09 So once again, please be careful.

00:03:11 I know that I'm trying to save some time for all of us, but as you can see, it can cause further issues.

00:03:17 So I'll change this over to tag and I'll change this over to tag as well.

00:03:23 Great.

00:03:23 Now let's create its definition.

00:03:25 The tag will be pretty simple.

00:03:27 It'll simply have a name, which will be a type string and it'll be required to true.

00:03:34 And each string also has to be unique.

00:03:37 So we can say unique is set to true.

00:03:40 Next, we can have the number of questions.

00:03:42 So this will simply be questions.

00:03:45 And it'll have a type is equal to number and a default of zero.

00:03:53 And did you see how chat GPT try to turn this into a collection of references?

00:03:58 Because it doesn't know the optimization we're trying to implement.

00:04:01 So it's good that we actually have it like this.

00:04:04 And it's good that you're watching this course.

00:04:05 After all, AI cannot do database architecture for you, at least not yet.

00:04:10 So let's give it a name of string and let's give it questions equal to number.

00:04:18 And in this case, we're not using types, so we can remove that.

00:04:21 Great.

00:04:21 So now we have our tag model.

00:04:23 And let's create the second one, which is going to be the tag question model.

00:04:28 I'll do that by creating a new file called tag-question.model.ts.

00:04:34 And we can copy the template within it.

00:04:36 But now I noticed why I have those issues.

00:04:38 I forgot to change those two keywords in the template itself.

00:04:42 So this should say model.

00:04:44 I'll copy the template and I'll paste it here.

00:04:48 I'll replace the model with tag question.

00:04:52 So this is now a joined collection.

00:04:54 And let's define the definition.

00:04:56 Hopefully it'll make more sense then.

00:04:58 So a tag question schema will contain a reference to a tag.

00:05:03 So it'll be a type object ID, ref tag, and it'll actually be required.

00:05:08 So we can say required.

00:05:10 is set to true.

00:05:11 And after that, we can get the question attached to that tag, which will be equal to type, object ID, with a reference to a question,

00:05:19 and required to true.

00:05:21 And see what Copilot did?

00:05:22 Once again, it took types.objectId, which are TypeScript types and not schema types.

00:05:28 So this is actually schema.types.objectId.

00:05:33 And let's actually define the types by giving it a tag of types dot object ID.

00:05:40 And let's also give it a question of a types object ID.

00:05:44 And with that, we have created those two different tag and tag questions models.

00:05:49 Hopefully the reasoning of why did we decide to create two separate collection makes sense.

00:05:53 The quick answer to that question is for easier and faster querying.

00:05:58 Whenever we need to fetch all the tags like this, we just get their names and the number of questions they have.

00:06:04 And when we need to find which tags are attached to each question like this, then we can use the tag question collection.

00:06:11 Great.