State Management for Multi-Page Apps | Dataford Interview Questions

How do you approach state management in a complex, multi-page application?

Implement reduce_app_state(initial_state, actions) as a pure reducer. Store shared records in normalized entities and order collections, while keeping each page's filter and selectedIds independent. Support navigate, set_filter, upsert_items, toggle_selected, and remove_item actions.

Input is a state dictionary and an action list. Return a new final state without mutating either input. Each record contains a unique string id.

Constraints

initial_state contains activePage, pages, entities, and order keys
Each page contains filter and selectedIds keys
Each entity has a unique string id
All action types are valid and reference existing pages and entity IDs when required
0 <= actions.length <= 1000
The input state and actions must not be mutated

Function Signature

def reduce_app_state(initial_state, actions):

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Problem

How do you approach state management in a complex, multi-page application?

Input is a state dictionary and an action list. Return a new final state without mutating either input. Each record contains a unique string id.

Constraints

initial_state contains activePage, pages, entities, and order keys
Each page contains filter and selectedIds keys
Each entity has a unique string id
All action types are valid and reference existing pages and entity IDs when required
0 <= actions.length <= 1000
The input state and actions must not be mutated

Function Signature

def reduce_app_state(initial_state, actions):

Your question is State Management for Multi-Page Apps. Start with the requirements in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.