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‫In this video, let's continue to translate

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‫the data model that we established right at the beginning

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‫of the section into some actual code.

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‫And so, this time we're gonna implement the reviews model.

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‫So the first step is to create a new file

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‫in the models folder and call it ReviewModel.js.

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‫And to me, this looks like yet another great challenge

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‫for you to practice some of the skills

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‫that you already learned up to this point.

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‫Okay so, in this challenge, I want you to create

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‫the review model.

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‫And what we need in there is actually very simple.

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‫So let me put that here in a comment.

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‫So we basically want a review,

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‫so the text for the review.

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‫We want a rating

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‫so just like this.

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‫Then we also want a createdAt

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‫so with the current timestamp

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‫and then we also want a reference to the tour

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‫that this review belongs to

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‫and also to the user who wrote this review.

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‫Okay, so basically two parent references here, right.

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‫And so with the stuff that you learned

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‫in the last couple of lectures,

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‫you should be able to actually complete this challenge

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‫completely on your own.

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‫So, pause the video now and good luck with that.

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‫Now, okay, so I hope you didn't just skip this

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‫and instead, you really implemented it by yourself

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‫and anyway, this is how I created it.

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‫So of course, we need to start by requiring mongoose

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‫and then

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‫the reviewSchema is equal to new mongoose.Schema.

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‫And so let's start adding our fields.

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‫So first the review is of course a string.

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‫Now, right and of course, I'm doing this too fast,

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‫so I also need to specify type

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‫and then let's also set it to a required,

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‫true,

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‫review can not be empty.

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‫Then we want a rating,

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‫and this one is of the type number.

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‫And the rating is ideally between one and five.

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‫And so the minimum of one and the max is five.

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‫So as you already know,

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‫these are some simple validators.

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‫That work only for numbers, right.

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‫This is not correct here.

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‫Okay.

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‫Next up, the createdAt.

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‫Into this is of type, date,

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‫and by default we want

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‫Date.now.

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‫Okay.

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‫So this was the easy part.

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‫And lets actually also create a model

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‫and export it before adding these references.

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‫So const,

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‫Review is equal too mongoose.model

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‫with the name Review.

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‫And then of course reviewSchema.

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‫To finish of course module.export

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‫equals the Review.

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‫Alright, and now comes the reference part.

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‫So a review of course needs to belong to a tour.

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‫And it also needs an author.

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‫Okay.

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‫So that's again what we specified

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‫in our data modeling lecture.

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‫So basically that we were going to implement

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‫parent referencing here in this case.

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‫Because both the tour and the user

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‫are in a sense the parents of this data set.

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‫And we decided to do it this way

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‫because we are going to potentially

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‫huge erase any parent elements right?

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‫So we should not design our application

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‫thinking that there will only be a few reviews.

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‫Only to then come back to it after some time

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‫and find out that our assumptions were wrong.

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‫And now we need to rebuild our entire data model.

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‫So that would be terrible.

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‫So in many situations, as you already know

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‫what we do not really know, how much our erase will grow.

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‫Then it's just best to opt for parent referencing.

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‫So again, that's exactly what we're doing here

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‫when we're referencing tour and user.

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‫So lets actually now go ahead and implement that.

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‫And starting with the tour.

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‫Alright.

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‫So here we need some space, and okay.

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‫So the type is as we did before, mongoose,

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‫and that's not correct.

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‫So mongoose.Schema.ObjectId,

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‫with a capital O and a capital I, but not the D.

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‫And I'm just telling you that

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‫because I once wrote ID like this,

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‫and then spent half an hour trying to figure out

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‫why my application wasn't working.

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‫Okay, so this D needs to be lowercase.

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‫Anyway.

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‫The reference in this case is of course the tour.

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‫And we also want to make this required.

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‫So true and then Review must belong

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‫to a tour.

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‫Okay.

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‫And just like this, each Review document now knows

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‫exactly what tour it belongs too.

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‫While the tour of course doesn't know initially

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‫what Reviews and how many Reviews there are.

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‫But that it a problem that

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‫we will actually solve a bit later.

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‫Okay.

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‫Next up, when there is a Review, we not only

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‫want to know what tour it belongs to,

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‫but also who wrote this Review.

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‫So user,

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‫and again, the same type of

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‫mongoose.Schema.ObjectId,

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‫and this time

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‫the reference, as you can imagine is gonna be user.

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‫Okay, and again we make it required

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‫because well, a review really cannot work

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‫without an author basically.

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‫And so review

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‫must belong to a user.

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‫Okay, that's actually it.

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‫Alright.

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‫Now just to finish lets actually also add these options

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‫to the Schema where we make it so that virtual properties

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‫also show up in Json and object outputs.

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‫Okay.

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‫So we did that before in the tours.

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‫I'm not sure if we did it in the user model.

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‫But anyway, here we are actually

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‫gonna need it a bit later.

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‫So we need to specify that.

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‫Remember, basically what I mean

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‫is this part.

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‫So I'm actually going to go ahead and copy it.

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‫Just to save us some time.

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‫And so again, all this does is to really make sure

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‫that when we have a virtual property,

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‫basically a field that is not stored in the database

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‫but calculated using some other value.

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‫So we want this to also show up whenever there is an output.

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‫Right, and so that's what we do here.

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‫Okay.

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‫And so I actually think that's actually it for now.

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‫Very simple.

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‫The only a bit tricky part is actually to create

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‫these references here.

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‫But we actually did that before

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‫and so it really works in the exact same way.

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‫So in the next video we will then use the Schema

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‫in order to create some new reviews.

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‫So see you then.