GO and GraphQL

Question 1

What is Go (Golang)?

Answer 1

An open-source programming language designed for simplicity, concurrency, and performance.

Question 2

What is the purpose of goroutines in Go?

Answer 2

To allow lightweight concurrent execution of functions.

Question 3

What is a channel in Go?

Answer 3

A mechanism to communicate between goroutines and synchronize their execution.

Question 4

How does Go manage memory?

Answer 4

Go uses a garbage collector to automatically manage memory allocation and deallocation.

Question 5

What is the use of defer in Go?

Answer 5

To schedule a function call to run after the function completes, often used for cleanup.

Question 6

What are Go interfaces?

Answer 6

A type that specifies method signatures. Types implicitly implement interfaces by defining those methods.

Question 7

What is the zero value in Go?

Answer 7

The default value a variable has when declared without explicit initialization.

Question 8

What is a struct in Go?

Answer 8

A composite type that groups variables (fields) under one name.

Question 9

What is a Go module?

Answer 9

A collection of related Go packages with versioning, defined in a go.mod file.

Question 10

What is the go.mod file?

Answer 10

Defines the module’s path and its dependency versions.

Question 11

What is GraphQL?

Answer 11

A query language for APIs that allows clients to request exactly the data they need.

Question 12

What is a GraphQL schema?

Answer 12

A contract that defines types, queries, mutations, and subscriptions for a GraphQL API.

Question 13

What are resolvers in GraphQL?

Answer 13

Functions that return data for specific fields in a GraphQL schema.

Question 14

What is a query in GraphQL?

Answer 14

A read operation that requests data from the server.

Question 15

What is a mutation in GraphQL?

Answer 15

A write operation used to modify server-side data.

Question 16

What is a subscription in GraphQL?

Answer 16

Allows clients to receive real-time updates from the server.

Question 17

What is introspection in GraphQL?

Answer 17

The ability for clients to query the schema itself for available types and fields.

Question 18

What is a scalar type in GraphQL?

Answer 18

Basic data types such as Int, Float, String, Boolean, and ID.

Question 19

What is a custom scalar in GraphQL?

Answer 19

User-defined scalar types used to represent complex values like DateTime.

Question 20

What is a fragment in GraphQL?

Answer 20

Reusable selection sets that can be used across multiple queries.

Question 21

What is gqlgen?

Answer 21

A Go library for building GraphQL servers with type-safe resolvers generated from schemas.

Question 22

How does gqlgen generate code?

Answer 22

It uses a schema-first approach to generate Go code from .graphql schema files.

Question 23

Where do gqlgen resolvers live?

Answer 23

In the resolver.go file under the graph package by default.

Question 24

How do you define schema in gqlgen?

Answer 24

Using .graphql files with type, query, and mutation definitions.

Question 25

How do you customize resolver behavior in gqlgen?

Answer 25

By implementing interface methods in the resolver struct.

Question 26

What file is used to configure gqlgen?

Answer 26

`gqlgen.yml` defines codegen settings and resolver binding.

Question 27

What is the role of the generated.go file?

Answer 27

Contains generated types and boilerplate resolver interfaces.

Question 28

How do you run gqlgen code generation?

Answer 28

`go run github.com/99designs/gqlgen generate`

Question 29

What package does gqlgen use for HTTP routing?

Answer 29

You can use `net/http`, `mux`, or `chi` with `handler.GraphQL()`.

Question 30

What is context.Context used for in GraphQL resolvers?

Answer 30

To pass request-scoped values like auth tokens or user ID.

Question 31

How do you handle authentication in Go GraphQL?

Answer 31

Using middleware to extract auth data and store it in the context.

Question 32

How can you validate GraphQL inputs in Go?

Answer 32

Using custom resolvers and validation logic in input types.

Question 33

How do you paginate data in GraphQL?

Answer 33

Using `first`, `after`, `last`, `before` arguments with cursors.

Question 34

What is the N+1 problem in GraphQL?

Answer 34

Repeated fetching of related data leading to performance issues.

Question 35

How do you solve the N+1 problem in Go GraphQL?

Answer 35

Using a data loader to batch and cache related field resolutions.

Question 36

How can you log GraphQL queries in Go?

Answer 36

Using middleware or custom logger with the `handler` package.

Question 37

How do you test GraphQL APIs in Go?

Answer 37

Using HTTP integration tests and mocking resolver dependencies.

Question 38

What are some performance optimizations for Go GraphQL APIs?

Answer 38

Schema stitching, batched resolvers, caching, and connection pooling.

Question 39

How do you expose metrics for a Go GraphQL API?

Answer 39

Using Prometheus metrics with middleware or custom handlers.

Question 40

What is the difference between input and type in GraphQL?

Answer 40

`type` defines output fields, while `input` is used for arguments.

Question 41

How do you create reusable types in GraphQL?

Answer 41

By defining common fields in fragments or shared input types.

Question 42

What is non-nullable field in GraphQL?

Answer 42

A field marked with `!`, meaning it must not be null.

Question 43

Can GraphQL support file uploads?

Answer 43

Yes, using the `multipart/form-data` spec and libraries like `graphql-upload`.

Question 44

What is schema stitching in GraphQL?

Answer 44

Combining multiple schemas into a single API endpoint.

Question 45

How do you handle versioning in GraphQL APIs?

Answer 45

By deprecating fields and evolving types carefully.

Question 46

What is federation in GraphQL?

Answer 46

A technique for building a unified GraphQL schema from multiple services.

Question 47

What is the @deprecated directive used for?

Answer 47

Marks schema fields as deprecated with a reason string.

Question 48

What is a GraphQL playground?

Answer 48

An in-browser IDE for writing and testing GraphQL queries.

Question 49

How do you handle errors in GraphQL resolvers?

Answer 49

By returning Go errors which GraphQL includes in the `errors` field of the response.