Query Practice!

Today we're going to practice writing some Prisma Queries. If you look at prisma/schema.prisma you can see that we've set up a database schema for you that relates users to movies with ratings.

This means we should be able to look for things like:

• What movies has the user with the name "jon higger" rated ?
• What users have rated the movie with the title "forrest gump" ?
• What is the average rating of the movie titled "forrest gump" ?

Why the F are we using typescript?

Don't freak out but we're about to level you up. While Javascript is great, we can get some really cool benefits from using Typescript, especially on large projects. Don't worry that's a different lesson for a different day, but you will technically be writing some typescript RIGHT TF NOW!

One of the cool parts about typescript is that it is a superset of javascript, in the same way a rectangle is a superset of a square! That means that in most circumstances typescript code looks exactly the same as javascript code, and if it ever does look different it only is in the type annotations.

Let's look at the following javascript code which takes a first name and a last name and builds a full name.

const firstName = "Naruto" 
const lastName = "Uzumaki"
const fullName = `${firstName} ${lastName}`

Let's now look at the same code but in typescript

const firstName = "Naruto"  // typescript can infer that `firstName` is a string
const lastName = "Uzumaki" // typescript can infer that `lastName` is a string
const fullName = `${firstName} ${lastName}` // typescript can infer that `fullName` is a string

Wait what?!?! It's the same exact code. Told ya so! Now let's get into where it can be slightly different. Here is a function in js that takes in the parameters firstName and lastName.

function getFullName(firstName, lastName){
    return `${firstName} ${lastName}`
}

Now let's try and write this in TS. Go copy this snippet into messaround.ts and see if typescript is happy!

function getFullName(firstName, lastName){
    return `${firstName} ${lastName}`
}

Turns out.... It's not. It's actually mad because on the parameters firstName and lastName we never specified what it's type was, and typescript doesn't have enough information here to make a good guess (we call this inferring). There's a number of ways to solve this but the fastest and easiest way right now is to just use a Type Annotation. Here, we're just going to say that the firstName and lastName parameters each have to be a string.

function getFullName(firstName: string, lastName: string){
    return `${firstName} ${lastName}`
}

In this lesson this is about all the typescript you will need to understand. If you're curiosity is piqued check out The Typescript Docs they are awesome. But for this lesson you really shouldn't need to do anything fancy other than that! We'll have more on this as we move forward!

Writing Prisma Queries

To begin run this in your terminal:

npx prisma migrate dev

This will take your prisma.schema and generate a database for you. Before every test runs we will clear the database and seed the database. That means you'll always be working with the same data. To look at what that data should be you have two options:

1. Look at the seed.ts file to see what all get's seeded before each test
2. run npx prisma studio in your terminal to go through prisma's built in data explorer

That's all the help we're giving you on this one,

By now you know the drill about how these tested assignments work, but we want you to learn a little bit more about how to use tools like Vitest. One thing you will notice is there is no test-all test-1 scripts. Now that is up to you to configure! As you become a more experienced developer you are going to need to learn some things from documentation without our help. If you can... Try to use The Vitest CLI Docs in order to figure out how to run these tests yourself.

If you get really really stuck on running these tests, you can also visit the #in-class channel on discord and look for some videos on testing to give you the vibe for how vitest or jest works.

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Read about the Prisma documentation here, run your tests, and get the code to pass

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