Store-to-store interaction in Vue - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import a Vue Composition API function often used with Pinia stores.

Vue

import { defineStore } from 'pinia';
import { [1] } from 'vue';

Drag options to blanks, or click blank then click option'

Aref

Breactive

Ccomputed

Dwatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'computed' instead of 'ref' when importing from 'vue'.

Forgetting to import 'ref' when working with reactive data.

We use ref to create reactive references in Vue 3, which is often imported alongside stores.

2fill in blank

medium

Complete the code to define a Pinia store named 'userStore'.

Vue

export const useUserStore = defineStore('[1]', {
  state: () => ({
    name: '',
    age: 0
  })
});

Drag options to blanks, or click blank then click option'

Aprofile

BuserStore

Cuser

Daccount

Attempts:

3 left

💡 Hint

Common Mistakes

Using the variable name 'useUserStore' as the store id string.

Using uppercase letters in the store id.

The store id should be a unique string. Here, 'user' is used as the store id.

3fill in blank

hard

Fix the error in accessing another store inside a Pinia store action.

Vue

import { defineStore } from 'pinia';
import { useCartStore } from './cartStore';

export const useUserStore = defineStore('user', {
  actions: {
    addToCart(product) {
      const cart = [1]();
      cart.add(product);
    }
  }
});

Drag options to blanks, or click blank then click option'

AuseStore

BuseCartStore

CuseProductStore

DuseUserStore

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the wrong store function like 'useUserStore' inside the user store.

Trying to access the store without calling the function.

To access another store inside a store, you call its use function, here useCartStore().

4fill in blank

hard

Fill both blanks to correctly update state from another store inside an action.

Vue

export const useOrderStore = defineStore('order', {
  actions: {
    placeOrder() {
      const cart = [1]();
      this.items = cart.[2];
    }
  },
  state: () => ({
    items: []
  })
});

Drag options to blanks, or click blank then click option'

AuseCartStore

Bproducts

Citems

DuseProductStore

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'products' instead of 'items' for the cart state property.

Calling the wrong store function like 'useProductStore'.

We get the cart store instance with useCartStore() and access its items state to update the order store.

5fill in blank

hard

Fill all three blanks to create a store that reacts to another store's state using a getter.

Vue

export const useDiscountStore = defineStore('discount', {
  getters: {
    totalDiscount(state) {
      const cart = [1]();
      return cart.[2] * state.[3];
    }
  },
  state: () => ({
    discountRate: 0.1
  })
});

Drag options to blanks, or click blank then click option'

AuseCartStore

BtotalPrice

CdiscountRate

DuseUserStore

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'useUserStore' instead of 'useCartStore'.

Accessing wrong state properties like 'items' instead of 'totalPrice'.

The discount store gets the cart store instance with useCartStore(), accesses totalPrice from cart, and multiplies by its own discountRate.

Practice

1. What is the main purpose of store-to-store interaction in Vue's Pinia stores?

easy

A. To create multiple independent stores without any connection

B. To allow one store to access or call actions from another store

C. To replace Vue components with stores

D. To automatically sync stores with a backend database

Solution

1. Step 1: Understand store-to-store interaction

   Store-to-store interaction means one store can use another store's state or actions to share data or trigger updates.

2. Step 2: Identify the purpose

   This interaction helps keep data consistent by letting stores communicate, not by replacing components or syncing automatically.

3. Final Answer:

   To allow one store to access or call actions from another store -> Option B

4. Quick Check:

   Store-to-store interaction = Access other store's actions/state [OK]

Hint: Remember: stores talk by calling each other's actions [OK]

Common Mistakes:

• Thinking stores replace components
• Assuming stores sync automatically with backend
• Believing stores are always independent

2. Which of the following is the correct way to use one Pinia store inside another in Vue 3?

easy

A. const storeA = useStoreA(); const storeB = useStoreB(); import { useStoreA } from './storeA';

B. import useStoreA from './storeA'; const storeB = useStoreB();

C. const storeA = useStoreB(); const storeB = useStoreA();

D. import { useStoreA } from './storeA'; const storeB = useStoreB(); const storeA = useStoreA();

Solution

1. Step 1: Import the store function before usage

   You must import the store function (e.g., useStoreA) before calling it to get the store instance.

2. Step 2: Call the store functions to get instances

   Call useStoreA() and useStoreB() to get their store instances for interaction.

3. Final Answer:

   import { useStoreA } from './storeA'; const storeB = useStoreB(); const storeA = useStoreA(); -> Option D

4. Quick Check:

   Import then call stores = correct syntax [OK]

Hint: Always import store before calling useStore() [OK]

Common Mistakes:

• Calling useStore before importing
• Mixing store names when calling
• Incorrect import syntax without braces

3. Given these two Pinia stores, what will be the console output after calling storeB.incrementA()?

const useStoreA = defineStore('A', {
  state: () => ({ count: 0 }),
  actions: { increment() { this.count++ } }
});

const useStoreB = defineStore('B', {
  actions: {
    incrementA() {
      const storeA = useStoreA();
      storeA.increment();
      console.log(storeA.count);
    }
  }
});

const storeB = useStoreB();
storeB.incrementA();

medium

A. 1

B. 0

C. undefined

D. Error: useStoreA is not defined

Solution

1. Step 1: Understand storeA initial state and increment

   storeA starts with count = 0. Calling increment() increases count by 1.

2. Step 2: Trace incrementA action in storeB

   incrementA calls storeA.increment(), then logs storeA.count which is now 1.

3. Final Answer:

   1 -> Option A

4. Quick Check:

   Increment count from 0 to 1, then log 1 [OK]

Hint: Calling other store's action updates its state immediately [OK]

Common Mistakes:

• Assuming count stays 0 after increment
• Thinking console logs undefined
• Forgetting to call useStoreA inside action

4. What is wrong with this code snippet trying to use storeA inside storeB?

const useStoreA = defineStore('A', {
  state: () => ({ value: 10 })
});

const useStoreB = defineStore('B', {
  actions: {
    updateValue() {
      const storeA = useStoreA;
      storeA.value = 20;
    }
  }
});

medium

A. defineStore cannot be used inside actions

B. Cannot assign value directly to storeA.value

C. useStoreA is not called as a function, so storeA is not a store instance

D. State must be a function returning an object

Solution

1. Step 1: Check how useStoreA is used inside updateValue

   useStoreA is referenced without parentheses, so storeA is a function reference, not a store instance.

2. Step 2: Understand consequences of missing parentheses

   Without calling useStoreA(), you cannot access or modify state like storeA.value.

3. Final Answer:

   useStoreA is not called as a function, so storeA is not a store instance -> Option C

4. Quick Check:

   Call useStoreA() to get store instance [OK]

Hint: Always call useStore() with () to get the store [OK]

Common Mistakes:

• Forgetting parentheses when calling useStore
• Trying to assign state directly without actions
• Misunderstanding defineStore usage

5. You have two stores: useCartStore managing cart items and useUserStore managing user info. You want to clear the cart when the user logs out. How should you implement this store-to-store interaction inside useUserStore?

hard

A. Inside the logout action, call const cart = useCartStore(); cart.clearItems();

B. Emit an event from useUserStore and listen in useCartStore to clear items

C. Directly modify useCartStore state without calling its actions

D. Reset useUserStore state and expect useCartStore to reset automatically

Solution

1. Step 1: Identify the correct way to trigger cart clearing

   Calling useCartStore() inside useUserStore's logout action gets the cart store instance.

2. Step 2: Use cart store's action to clear items

   Calling cart.clearItems() properly updates the cart state in a controlled way.

3. Final Answer:

   Inside the logout action, call const cart = useCartStore(); cart.clearItems(); -> Option A

4. Quick Check:

   Call other store's action inside logout to clear cart [OK]

Hint: Call other store's action inside your store's action [OK]

Common Mistakes:

• Trying to modify other store's state directly
• Using events instead of direct store calls
• Expecting automatic reset without explicit calls