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3

Am not doing anything fancy, just trying to update a field on Contact in JS of LWC but getting this exception.

Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'Name'
throws at mydomain/auraFW/javascript/mhontaYdOya4Y_lBu7v9yg/aura_prod.js:2:27687

HTML Code:

<template>



    <template if:true={wiredContact}>



        {wiredContact.Name}



        <lightning-input value={wiredContact.Name} onchange={updateName}></lightning-input>

    </template>



</template>

JS:

import { LightningElement ,wire,track,api } from 'lwc';

import myContact from "@salesforce/apex/ContactController.fetchContact";



export default class Myrefreshapextest extends LightningElement {





 @track wiredContact;



 @wire (myContact)

        fetchedContact({error, data}){

            if(data){

                console.log(JSON.stringify(data));

                this.wiredContact = data;

            }else if (error){

                console.log(error);

            }

    }



    updateName (event){

        console.log(JSON.stringify(event.detail.value));

        console.log(JSON.stringify(this.wiredContact));

        this.wiredContact.Name = event.detail.value;

    }



}

Apex:

public class ContactController {



    @AuraEnabled(cacheable=true)

    public static Contact fetchContact(){

        return [SELECT Id,Name FROM COntact LIMIT  1];

    }

}

On top of my head, am not doing anything wrong, anyone has idea what's wrong with my code?

When I print console.log(JSON.stringify(this.wiredContact)); I get old values so am pretty sure it exists.

I tried with @track and @api, but same response. Can anyone shed some light?

lightning-web-components

share|improve this question

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you get same issue when you use the individual field names viz., FirstName?
  
  – Jayant Das
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Same error Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'FirstName' throws at its same error doesnt matter if its normal contact or personAccountContact.
  
  – Pranay Jaiswal
  4 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I got the error (not exactly the same) but was able to replicate. Seems like you cannot set a value directly to the property instead recreate the JSON and then assign. E.g., this.wiredContact = ["Name:" + event.detail.value]; this worked. Still trying to figure out.
  
  – Jayant Das
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @JayantDas It's a design feature. One that I'm pretty sure isn't documented.
  
  – sfdcfox
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @sfdcfox I just saw the behavior you mentioned just by trying it out, and it worked, even though my format above is not JSON, but I was intending that.
  
  – Jayant Das
  4 hours ago
  

  
  
  
  

 | 
show 1 more comment

3

Am not doing anything fancy, just trying to update a field on Contact in JS of LWC but getting this exception.

Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'Name'
throws at mydomain/auraFW/javascript/mhontaYdOya4Y_lBu7v9yg/aura_prod.js:2:27687

HTML Code:

<template>



    <template if:true={wiredContact}>



        {wiredContact.Name}



        <lightning-input value={wiredContact.Name} onchange={updateName}></lightning-input>

    </template>



</template>

JS:

import { LightningElement ,wire,track,api } from 'lwc';

import myContact from "@salesforce/apex/ContactController.fetchContact";



export default class Myrefreshapextest extends LightningElement {





 @track wiredContact;



 @wire (myContact)

        fetchedContact({error, data}){

            if(data){

                console.log(JSON.stringify(data));

                this.wiredContact = data;

            }else if (error){

                console.log(error);

            }

    }



    updateName (event){

        console.log(JSON.stringify(event.detail.value));

        console.log(JSON.stringify(this.wiredContact));

        this.wiredContact.Name = event.detail.value;

    }



}

Apex:

public class ContactController {



    @AuraEnabled(cacheable=true)

    public static Contact fetchContact(){

        return [SELECT Id,Name FROM COntact LIMIT  1];

    }

}

On top of my head, am not doing anything wrong, anyone has idea what's wrong with my code?

When I print console.log(JSON.stringify(this.wiredContact)); I get old values so am pretty sure it exists.

I tried with @track and @api, but same response. Can anyone shed some light?

lightning-web-components

share|improve this question

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Do you get same issue when you use the individual field names viz., FirstName?
  
  – Jayant Das
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Same error Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'FirstName' throws at its same error doesnt matter if its normal contact or personAccountContact.
  
  – Pranay Jaiswal
  4 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I got the error (not exactly the same) but was able to replicate. Seems like you cannot set a value directly to the property instead recreate the JSON and then assign. E.g., this.wiredContact = ["Name:" + event.detail.value]; this worked. Still trying to figure out.
  
  – Jayant Das
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @JayantDas It's a design feature. One that I'm pretty sure isn't documented.
  
  – sfdcfox
  4 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @sfdcfox I just saw the behavior you mentioned just by trying it out, and it worked, even though my format above is not JSON, but I was intending that.
  
  – Jayant Das
  4 hours ago
  

  
  
  
  

 | 
show 1 more comment

Am not doing anything fancy, just trying to update a field on Contact in JS of LWC but getting this exception.

Uncaught TypeError: 'set' on proxy: trap returned falsish for property 'Name'
throws at mydomain/auraFW/javascript/mhontaYdOya4Y_lBu7v9yg/aura_prod.js:2:27687

HTML Code:

<template>



    <template if:true={wiredContact}>



        {wiredContact.Name}



        <lightning-input value={wiredContact.Name} onchange={updateName}></lightning-input>

    </template>



</template>

JS:

import { LightningElement ,wire,track,api } from 'lwc';

import myContact from "@salesforce/apex/ContactController.fetchContact";



export default class Myrefreshapextest extends LightningElement {





 @track wiredContact;



 @wire (myContact)

        fetchedContact({error, data}){

            if(data){

                console.log(JSON.stringify(data));

                this.wiredContact = data;

            }else if (error){

                console.log(error);

            }

    }



    updateName (event){

        console.log(JSON.stringify(event.detail.value));

        console.log(JSON.stringify(this.wiredContact));

        this.wiredContact.Name = event.detail.value;

    }



}

Apex:

public class ContactController {



    @AuraEnabled(cacheable=true)

    public static Contact fetchContact(){

        return [SELECT Id,Name FROM COntact LIMIT  1];

    }

}

On top of my head, am not doing anything wrong, anyone has idea what's wrong with my code?

When I print console.log(JSON.stringify(this.wiredContact)); I get old values so am pretty sure it exists.

I tried with @track and @api, but same response. Can anyone shed some light?

lightning-web-components

share|improve this question

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

<template>



    <template if:true={wiredContact}>



        {wiredContact.Name}



        <lightning-input value={wiredContact.Name} onchange={updateName}></lightning-input>

    </template>



</template>

import { LightningElement ,wire,track,api } from 'lwc';

import myContact from "@salesforce/apex/ContactController.fetchContact";



export default class Myrefreshapextest extends LightningElement {





 @track wiredContact;



 @wire (myContact)

        fetchedContact({error, data}){

            if(data){

                console.log(JSON.stringify(data));

                this.wiredContact = data;

            }else if (error){

                console.log(error);

            }

    }



    updateName (event){

        console.log(JSON.stringify(event.detail.value));

        console.log(JSON.stringify(this.wiredContact));

        this.wiredContact.Name = event.detail.value;

    }



}

public class ContactController {



    @AuraEnabled(cacheable=true)

    public static Contact fetchContact(){

        return [SELECT Id,Name FROM COntact LIMIT  1];

    }

}

share|improve this question

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

share|improve this question

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

asked 4 hours ago

Pranay JaiswalPranay Jaiswal

18.6k53158

2 Answers
2

active

oldest

votes

3

Cached items are set as read-only (because otherwise you could corrupt the cache). If you want a modifiable object, you need to clone it.

this.wiredContact = Object.assign({}, data);

share|improve this answer

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 for Object.assign(). Didn't know something like this existed.
  
  – Jayant Das
  3 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks sfdcfox. You are truly a Javascript wizard.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  

add a comment | 

1

This is what I could find from the documentation for wired service and that seems to be the case here (emphasis mine).

The wire service provisions an immutable stream of data to the component

So it most likely seems that when trying to set the values directly using this.wiredContact.Name, because of it's read only property, the values are not getting set.

However if you try to create a new data and then assign it to this.wiredContact, it works:

this.wiredContact = "{Name:" + event.detail.value + "}";

share|improve this answer

answered 4 hours ago

Jayant DasJayant Das

18k21330

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This solution presumes only one field. If you have multiple fields, you must remember to encode all of them or lose data. The solution I presented avoids this problem by copying everything on initialization, leaving the variable free to be modified in all other function calls.
  
  – sfdcfox
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yeah, this was a more direct answer to the problem that Pranay had mentioned. I am not really good at JS, so didn't even know how to do so unless you mentioned.
  
  – Jayant Das
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 thanks for linking documentation. This was freaking me out.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I started looking only when @sfdcfox mentioned it was possibly not :) But at least it is mentioned. Easy to miss!
  
  – Jayant Das
  3 hours ago
  

  
  
  
  

add a comment | 

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3

Cached items are set as read-only (because otherwise you could corrupt the cache). If you want a modifiable object, you need to clone it.

this.wiredContact = Object.assign({}, data);

share|improve this answer

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 for Object.assign(). Didn't know something like this existed.
  
  – Jayant Das
  3 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks sfdcfox. You are truly a Javascript wizard.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  

add a comment | 

3

Cached items are set as read-only (because otherwise you could corrupt the cache). If you want a modifiable object, you need to clone it.

this.wiredContact = Object.assign({}, data);

share|improve this answer

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 for Object.assign(). Didn't know something like this existed.
  
  – Jayant Das
  3 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks sfdcfox. You are truly a Javascript wizard.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  

add a comment | 

Cached items are set as read-only (because otherwise you could corrupt the cache). If you want a modifiable object, you need to clone it.

this.wiredContact = Object.assign({}, data);

share|improve this answer

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

this.wiredContact = Object.assign({}, data);

share|improve this answer

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

answered 4 hours ago

sfdcfoxsfdcfox

263k12209456

1

This is what I could find from the documentation for wired service and that seems to be the case here (emphasis mine).

The wire service provisions an immutable stream of data to the component

So it most likely seems that when trying to set the values directly using this.wiredContact.Name, because of it's read only property, the values are not getting set.

However if you try to create a new data and then assign it to this.wiredContact, it works:

this.wiredContact = "{Name:" + event.detail.value + "}";

share|improve this answer

answered 4 hours ago

Jayant DasJayant Das

18k21330

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This solution presumes only one field. If you have multiple fields, you must remember to encode all of them or lose data. The solution I presented avoids this problem by copying everything on initialization, leaving the variable free to be modified in all other function calls.
  
  – sfdcfox
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yeah, this was a more direct answer to the problem that Pranay had mentioned. I am not really good at JS, so didn't even know how to do so unless you mentioned.
  
  – Jayant Das
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 thanks for linking documentation. This was freaking me out.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I started looking only when @sfdcfox mentioned it was possibly not :) But at least it is mentioned. Easy to miss!
  
  – Jayant Das
  3 hours ago
  

  
  
  
  

add a comment | 

1

This is what I could find from the documentation for wired service and that seems to be the case here (emphasis mine).

The wire service provisions an immutable stream of data to the component

So it most likely seems that when trying to set the values directly using this.wiredContact.Name, because of it's read only property, the values are not getting set.

However if you try to create a new data and then assign it to this.wiredContact, it works:

this.wiredContact = "{Name:" + event.detail.value + "}";

share|improve this answer

answered 4 hours ago

Jayant DasJayant Das

18k21330

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  This solution presumes only one field. If you have multiple fields, you must remember to encode all of them or lose data. The solution I presented avoids this problem by copying everything on initialization, leaving the variable free to be modified in all other function calls.
  
  – sfdcfox
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Yeah, this was a more direct answer to the problem that Pranay had mentioned. I am not really good at JS, so didn't even know how to do so unless you mentioned.
  
  – Jayant Das
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  +1 thanks for linking documentation. This was freaking me out.
  
  – Pranay Jaiswal
  3 hours ago
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  
  I started looking only when @sfdcfox mentioned it was possibly not :) But at least it is mentioned. Easy to miss!
  
  – Jayant Das
  3 hours ago
  

  
  
  
  

add a comment | 

This is what I could find from the documentation for wired service and that seems to be the case here (emphasis mine).

The wire service provisions an immutable stream of data to the component

So it most likely seems that when trying to set the values directly using this.wiredContact.Name, because of it's read only property, the values are not getting set.

However if you try to create a new data and then assign it to this.wiredContact, it works:

this.wiredContact = "{Name:" + event.detail.value + "}";

share|improve this answer

answered 4 hours ago

Jayant DasJayant Das

18k21330

this.wiredContact = "{Name:" + event.detail.value + "}";

share|improve this answer

answered 4 hours ago

Jayant DasJayant Das

18k21330

answered 4 hours ago

Jayant DasJayant Das

18k21330

answered 4 hours ago

Jayant DasJayant Das

18k21330