Prisma ORM with GraphQL - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output of this Prisma query in GraphQL?

Given a Prisma model User with fields id, name, and age, what will this GraphQL query return?

query {
  users(where: { age: { gt: 30 } }) {
    id
    name
  }
}

GraphQL

model User {
  id   Int    @id @default(autoincrement())
  name String
  age  Int
}

A SyntaxError: Invalid query

B [{ id: 2, name: "Bob" }]

C []

D [{ id: 1, name: "Alice" }, { id: 3, name: "Charlie" }]

💡 Hint

Think about filtering users older than 30.

The query filters users where age is greater than 30, returning their id and name. Only Alice and Charlie match.

📝 Syntax

intermediate

Which option correctly defines a Prisma schema for a Post with a relation to User?

Choose the correct Prisma schema snippet that defines a Post model with a relation to User via authorId.

A

model Post {
  id       Int    @id @default(autoincrement())
  title    String
  authorId Int
  author   User   @relation(fields: [authorId], references: [id])
}

B

model Post {
  id       Int    @id @default(autoincrement())
  title    String
  authorId Int @relation
  author   User
}

C

model Post {
  id       Int    @id
  title    String
  authorId Int
  author   User
}

D

model Post {
  id       Int    @id @default(autoincrement())
  title    String
  author   User   @relation(fields: [authorId])
}

💡 Hint

Relations require specifying both fields and references.

Option A correctly defines the relation with @relation(fields: [authorId], references: [id]). Others miss references or have syntax errors.

❓ optimization

advanced

How to optimize fetching posts with their authors in Prisma GraphQL query?

You want to fetch all posts with their authors' names efficiently. Which Prisma client query is best?

A prisma.post.findMany({ include: { author: true } })

B prisma.post.findMany({ select: { title: true } })

C prisma.post.findMany({ where: { author: { name: { contains: "A" } } } })

D prisma.post.findMany()

💡 Hint

Including related data avoids extra queries.

Option A uses include to fetch posts with author data in one query, improving efficiency.

🔧 Debug

advanced

What error does this Prisma GraphQL mutation cause?

Given this mutation, what error will occur?

mutation {
  createUser(data: { name: "Eve", age: "twenty" }) {
    id
    name
  }
}

A RuntimeError: User already exists

B SyntaxError: Invalid mutation syntax

C TypeError: age must be an Int, not a String

D No error, user created successfully

💡 Hint

Check the data types in the mutation.

The age field expects an integer, but a string "twenty" is provided, causing a type error.

🧠 Conceptual

expert

Which statement best describes Prisma's role in a GraphQL API?

Choose the most accurate description of how Prisma works with GraphQL.

A Prisma is a frontend library that renders GraphQL queries in the browser.

B Prisma acts as an ORM that maps GraphQL queries directly to database operations, simplifying data fetching and mutations.

C Prisma replaces GraphQL and handles all API requests internally without a schema.

D Prisma only works with REST APIs and cannot be used with GraphQL.

💡 Hint

Think about Prisma's function between your database and GraphQL server.

Prisma is an ORM that helps translate GraphQL queries into efficient database commands, making backend development easier.