Graph QLStudy Notes

Aliases and Fragments

Learn how aliases let you request the same field multiple times with different arguments, and how fragments keep repeated selection sets DRY.

Apollo Client Basics

Learn how Apollo Client manages GraphQL queries, mutations, and the normalized cache in front-end applications.

Authentication and Authorization in GraphQL

Learn how to authenticate requests and enforce field-level authorization in a GraphQL API, and avoid common security pitfalls.

Custom Scalars

How to model domain-specific leaf values beyond GraphQL's five built-in scalars using serialize, parseValue, and parseLiteral.

DataLoader and the N+1 Problem

Understand why naive GraphQL resolvers trigger the N+1 query problem and how Facebook's DataLoader batches and caches requests to fix it.

Directives in GraphQL

Understand built-in and custom GraphQL directives, how they alter query execution and schema behavior, and where to apply them safely.

Enums in GraphQL

How GraphQL enums restrict fields and arguments to a fixed, validated set of named values, and how their SDL names map to internal server representations.

Error Handling in Resolvers

Learn how GraphQL's partial-response error model works, how nullability affects error propagation, and how to design custom, informative errors.

GraphQL Code Generation

Understand how GraphQL Code Generator produces type-safe TypeScript types, hooks, and resolvers from your schema and operations.

GraphQL Interview Questions

A curated set of common GraphQL interview questions and model answers covering core concepts, performance, and real-world tradeoffs.

GraphQL Quick Reference

A condensed cheat sheet of core GraphQL syntax, type system rules, and common patterns for fast lookup.

GraphQL vs REST

A practical comparison of GraphQL and REST across data fetching, versioning, and caching, and when to choose each.

Input Types

Learn how GraphQL input object types bundle structured arguments together, especially for mutations, and how they differ from regular object types.

Interfaces and Unions

How GraphQL's two abstract types — interfaces with guaranteed shared fields, and unions with no shared contract — let a single field return polymorphic results.

Mutations Explained

Learn how GraphQL mutations perform writes, why they execute serially, and how to structure inputs and response payloads.

Nullable vs Non-Nullable Types

Why fields are nullable by default in GraphQL, what the `!` modifier guarantees, and how null bubbling propagates a single resolver failure up the response tre…

Pagination Patterns: Cursor vs Offset

Compare offset-based and cursor-based pagination in GraphQL, and understand why the Relay connection spec is the industry-standard approach.

Query Arguments and Variables

Learn how GraphQL fields accept arguments to parameterize what they return, and how variables keep queries reusable, safe, and cacheable.

Resolver Functions Explained

Learn what resolver functions are, how their four arguments work, and how GraphQL servers turn a query into actual data.

Resolving Nested Fields

See how GraphQL resolves deeply nested object fields, including lists of objects, and why field resolution order matters for performance.

Scalar and Object Types

A deep dive into GraphQL's built-in scalar types, custom scalars, enums, and how object types compose the graph.

Schema Stitching and Federation

Learn the two main approaches to composing multiple GraphQL services into a single unified graph, and when to choose each.

Setting Up a GraphQL Server

A hands-on walkthrough of standing up a GraphQL server with Apollo Server, from schema and resolvers to running your first query.

Subscriptions Explained

Learn how GraphQL subscriptions deliver real-time updates over a persistent connection, and how to run them reliably in production.