createEntityAdapter

The problem

Users live in an array. Update one name and you map() the whole list. Lookup is find(). Two copies of the same id drift. Relational data (posts by authorId) becomes nested map soup.

The pattern that fixes it

Normalized shape: ids[] + entities{}. upsertOne / updateOne / removeOne / selectById. createEntityAdapter generates those reducers and selectors. Same idea as a database table.

Keep learning

• Previous: extraReducers + matchers
• Next: createSelector
• Related: configureStore
• Related: createAction
• Related: extraReducers + matchers
• Related: createSelector
• Related: createListenerMiddleware
• Related: combineSlices / inject

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