Issue with updating Parent value in Vue component when Child value changes

Question

Issue with updating Parent value in Vue component when Child value changes

I am working with an Array to fill a Dialog Vue Component. My setup looks like this:

           basicInfo: [{ firstName: "John" , lastName: "Doe" }],

          <basicInfoForm v-model="showBasicInfoForm" :basicInfo="newbasicInfo[0]"></basicInfoForm>

In the Parent component, I have

       {{basicInfo[0].firstName + ' ' + basicInfo[0].lastName}}

There is a button that triggers a Form Component within a Dialog popup for editing. The issue I am facing is that any changes made in the Dialog reflect immediately on the Parent as well. I want to include a cancel button in the Child Dialog so changes can be reverted. To achieve this, I cloned the array before passing it:

       this.newbasicInfo = this.basicInfo.slice();

And in the Child Dialog component,

      <v-text-field
      v-model="basicInfo.firstName"
      label="First Name"
      class="input-name styled-input"
       ></v-text-field> 

      props: {
      value: Boolean,
      basicInfo: Array
      },

The concern here is that every keystroke updates both the basicInfo array and the newbasicInfo array simultaneously, making it impossible to revert back to the original data if a cancel action is taken. As a beginner in Vue and Components, I might have misconfigured something. What could be causing changes to occur in both arrays at the same time?

javascript vue.js dialog

Answer 1

Answer №1

The situation here involves copying the array by reference, which results in both arrays being modified when one index is changed due to sharing the same reference. To resolve this issue, it's essential to copy the array by values instead.

An effective way to achieve this is by using the following code snippet:

this.copyOfBasicInfo = JSON.parse(JSON.stringify(this.basicInfo));

If you'd like more information related to this topic, feel free to refer to this question on Stack Overflow: How do you clone an Array of Objects in Javascript?

Answer 2

The situation here involves copying the array by reference, which results in both arrays being modified when one index is changed due to sharing the same reference. To resolve this issue, it's essential to copy the array by values instead.

An effective way to achieve this is by using the following code snippet:

this.copyOfBasicInfo = JSON.parse(JSON.stringify(this.basicInfo));

If you'd like more information related to this topic, feel free to refer to this question on Stack Overflow: How do you clone an Array of Objects in Javascript?

Answer 3

Answer №2

Your method for cloning objects within an array seems to have a limitation:

const basicInfo = [{ firstName: "John" , lastName: "Doe" }]
const newbasicInfo = basicInfo.slice()

While this method creates a "shallow copy", it only works effectively with simple data types like numbers and strings. When dealing with objects, the cloned objects still reference the original ones, making them essentially the same objects.

const basicInfo = [{ firstName: "John" , lastName: "Doe" }]
const newbasicInfo = JSON.parse(JSON.stringify(basicInfo))

Instead, using this approach to create a "deep copy" ensures that all nested elements are also cloned without maintaining references.

If your array consists of basic values, a shallow copy is faster. However, if objects are involved, opting for a deep copy is necessary.

Therefore, this issue is not specific to Vue but rather a fundamental JavaScript concept.

Here's a brief example to showcase the distinction:

const basicInfo1 = [{
  firstName: "John",
  lastName: "Doe"
}]
const newbasicInfo1 = basicInfo1.slice()

newbasicInfo1[0].firstName = "Johnnyboy"
console.log('basicInfo1: ', basicInfo1)
console.log('newbasicInfo1: ', newbasicInfo1)



const basicInfo2 = [{
  firstName: "John",
  lastName: "Doe"
}]
const newbasicInfo2 = JSON.parse(JSON.stringify(basicInfo2))

newbasicInfo2[0].firstName = "Johnnyboy"
console.log('basicInfo2: ', basicInfo2)
console.log('newbasicInfo2: ', newbasicInfo2)

Answer 4

Your method for cloning objects within an array seems to have a limitation:

const basicInfo = [{ firstName: "John" , lastName: "Doe" }]
const newbasicInfo = basicInfo.slice()

While this method creates a "shallow copy", it only works effectively with simple data types like numbers and strings. When dealing with objects, the cloned objects still reference the original ones, making them essentially the same objects.

const basicInfo = [{ firstName: "John" , lastName: "Doe" }]
const newbasicInfo = JSON.parse(JSON.stringify(basicInfo))

Instead, using this approach to create a "deep copy" ensures that all nested elements are also cloned without maintaining references.

If your array consists of basic values, a shallow copy is faster. However, if objects are involved, opting for a deep copy is necessary.

Therefore, this issue is not specific to Vue but rather a fundamental JavaScript concept.

Here's a brief example to showcase the distinction:

const basicInfo1 = [{
  firstName: "John",
  lastName: "Doe"
}]
const newbasicInfo1 = basicInfo1.slice()

newbasicInfo1[0].firstName = "Johnnyboy"
console.log('basicInfo1: ', basicInfo1)
console.log('newbasicInfo1: ', newbasicInfo1)



const basicInfo2 = [{
  firstName: "John",
  lastName: "Doe"
}]
const newbasicInfo2 = JSON.parse(JSON.stringify(basicInfo2))

newbasicInfo2[0].firstName = "Johnnyboy"
console.log('basicInfo2: ', basicInfo2)
console.log('newbasicInfo2: ', newbasicInfo2)

Issue with updating Parent value in Vue component when Child value changes

Answer №1

Answer №2

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