What problem does it solve?
Pinia documentation and patterns for Vue 3 solve the complexity of designing, typing, and maintaining application state by providing clear conventions for setup-style stores, actions, getters, and persistence. It reduces bugs caused by inconsistent store structure, unclear typing, circular dependencies, and ad-hoc testing approaches. The guidance helps teams scale state management across SSR, hydration, and TypeScript projects while preserving reactivity and testability.
Core Features & Use Cases
- Setup stores (Composition API): How to define stores with defineStore using refs, computed, and composables for better type inference.
- State, getters, and actions: Patterns for typed state, memoized getters, and robust async actions with loading/error handling.
- Store composition & shared state: Techniques to compose stores, avoid circular dependencies, and extract shared logic into composables.
- Persistence, hydration & SSR: Approaches for localStorage/session persistence, server hydration, and selective/lazy hydration patterns.
- Testing & migration: Strategies for unit testing stores, mocking APIs, and migrating from Vuex to Pinia.
- Use Case: Build a typed checkout flow that composes auth and cart stores, persists cart state, validates checkout steps, and provides test coverage for async order submission.
Quick Start
Set up Pinia in your Vue 3 project by creating a Pinia instance in main, applying it to the app, and defining a setup-style store with defineStore that returns refs, computed properties, and typed actions.