modifying prop values with Vue.js method

Question

modifying prop values with Vue.js method

I'm currently diving into Vue and tackling a project that heavily relies on vue.js. My goal is to display data in a component using a prop, and now I'm looking to implement a method to increment the quantity of a product.

Below is my code snippet:

<div v-for="(products, index) in products">
  <mdc-layout-cell span="2" align="middle">
    {{ products.product_barcode }}
  </mdc-layout-cell>
<mdc-layout-cell span="2" align="middle">
  {{ products.product_quantity}}
</mdc-layout-cell>
<i class="mdc-icon-toggle material-icons float-left"
   aria-pressed="false"
   v-on:click="incrementItem(index)">
  add
</div>

Here's the relevant JS:

export default {
    props: [
      'products',
    ],
    methods: {

      incrementItem(index) {
        let item = this.products[index];
        this.products[index].product_quantity =
          this.products[index].product_quantity + 1;
          console.log(this.products[index].product_quantity);
      },
    }

While I can see the incremented value in the console, it doesn't seem to update in the corresponding row. How can I successfully increase the product_quantity value? Any guidance would be greatly appreciated.

javascript vue.js vue-component

Answer 1

Answer №1

It is crucial to remember not to directly mutate props in the vue flow. Instead, make changes to the data in the parent component. One way to do this is by creating a copy of the props in the children's data. By doing so, when a button is clicked, the children's data will change, followed by a change in the parent's data, which in turn updates the children's props. There are multiple methods to achieve this. Below is a general code snippet to guide you:

Utilizing sync

In the parent component:

<parent :products.sync=products />

In the children component methods:

data() {
  return {
    productListInChildren: this.products; // passing props to children's inner data
  }
},
methods: {
    incrementItem(index) {
       // modify productListInChildren
       let item = this.productListInChildren[index];
        this.productListInChildren[index].product_quantity =
          this.productListInChildren[index].product_quantity + 1;
        // emit the updated data back to parents
        this.$emit('update:products', this.productListInChildren)
  }
}

<div v-for="(products, index) in productListInChildren"> // using productListInChildren instead
  <mdc-layout-cell span="2" align="middle">
    {{ products.product_barcode }}
  </mdc-layout-cell>
  <mdc-layout-cell span="2" align="middle">
    {{ products.product_quantity}}
  </mdc-layout-cell>
  <i class="mdc-icon-toggle material-icons float-left"
     aria-pressed="false"
     v-on:click="incrementItem(index)">
    add </i>
</div>

Another important point regarding code design is that in your case, the logic related to changing data should be handled by the parent component (smart component). The children components should primarily focus on displaying data or being "dumb components". If this is applicable to your situation, create a method in the parent component to handle the increment logic:

In the parent component:

<parent :products=products @increment="incrementInParent"/>

methods: {
incrementInParent() {// move the logic here}
}

In the children component:

methods: {
    incrementItem(index) {
       // call the method in the parent component
       this.$emit("increment");
  }
}

Answer 2

It is crucial to remember not to directly mutate props in the vue flow. Instead, make changes to the data in the parent component. One way to do this is by creating a copy of the props in the children's data. By doing so, when a button is clicked, the children's data will change, followed by a change in the parent's data, which in turn updates the children's props. There are multiple methods to achieve this. Below is a general code snippet to guide you:

Utilizing sync

In the parent component:

<parent :products.sync=products />

In the children component methods:

data() {
  return {
    productListInChildren: this.products; // passing props to children's inner data
  }
},
methods: {
    incrementItem(index) {
       // modify productListInChildren
       let item = this.productListInChildren[index];
        this.productListInChildren[index].product_quantity =
          this.productListInChildren[index].product_quantity + 1;
        // emit the updated data back to parents
        this.$emit('update:products', this.productListInChildren)
  }
}

<div v-for="(products, index) in productListInChildren"> // using productListInChildren instead
  <mdc-layout-cell span="2" align="middle">
    {{ products.product_barcode }}
  </mdc-layout-cell>
  <mdc-layout-cell span="2" align="middle">
    {{ products.product_quantity}}
  </mdc-layout-cell>
  <i class="mdc-icon-toggle material-icons float-left"
     aria-pressed="false"
     v-on:click="incrementItem(index)">
    add </i>
</div>

Another important point regarding code design is that in your case, the logic related to changing data should be handled by the parent component (smart component). The children components should primarily focus on displaying data or being "dumb components". If this is applicable to your situation, create a method in the parent component to handle the increment logic:

In the parent component:

<parent :products=products @increment="incrementInParent"/>

methods: {
incrementInParent() {// move the logic here}
}

In the children component:

methods: {
    incrementItem(index) {
       // call the method in the parent component
       this.$emit("increment");
  }
}

Answer 3

Answer №2

Capture the value of props and store it in a variable, then pass it to a child component.

export default {
    props: {
      items: Array,
    },
    data(){
     return {
       newItems: this.items,
     }
   }
}

In the child component, modify the structure of the props and use newItems. When updating data in the parent component, make sure to use emit for communication from the child to the parent.

To learn more about parent-child communication, check out this tutorial:

Answer 4

Capture the value of props and store it in a variable, then pass it to a child component.

export default {
    props: {
      items: Array,
    },
    data(){
     return {
       newItems: this.items,
     }
   }
}

In the child component, modify the structure of the props and use newItems. When updating data in the parent component, make sure to use emit for communication from the child to the parent.

To learn more about parent-child communication, check out this tutorial:

Answer 5

Answer №3

It is important to avoid mutating props directly in the child component and instead use event communication pattern for effective parent-child communication. When updating a specific value within an array or modifying a property in an object, Vue's reactivity might not work as expected due to Object and Array Caveats. For further information, you can visit this link:

https://v2.vuejs.org/v2/guide/reactivity.html

To ensure that changes in Objects and Arrays are reflected in the template, you can utilize $set. I have provided a sandbox URL that addresses your query here:

https://codesandbox.io/s/patient-brook-nf1w5?fontsize=14&hidenavigation=1&theme=dark

Answer 6

It is important to avoid mutating props directly in the child component and instead use event communication pattern for effective parent-child communication. When updating a specific value within an array or modifying a property in an object, Vue's reactivity might not work as expected due to Object and Array Caveats. For further information, you can visit this link:

https://v2.vuejs.org/v2/guide/reactivity.html

To ensure that changes in Objects and Arrays are reflected in the template, you can utilize $set. I have provided a sandbox URL that addresses your query here:

https://codesandbox.io/s/patient-brook-nf1w5?fontsize=14&hidenavigation=1&theme=dark

modifying prop values with Vue.js method

Answer №1

Answer №2

Answer №3

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