How to Create Record from LWC using External Id in lookup fields

Question

I'm trying to create an object in LWC, without using Apex. So I found out that we can do that with CreateRecord from uiRecordApi :

But I'm trying to create a Custom Object (ClientMember__c in our example) that have a lookup on Account

I tried this (CLIENTUID_FIELD or CLIENTUID_FIELD2):

import { LightningElement } from 'lwc';
import { createRecord } from 'lightning/uiRecordApi';
import { ShowToastEvent } from 'lightning/platformShowToastEvent';

import CLM_OBJECT from '@salesforce/schema/ClientMember__c';

import CLIENTUID_FIELD from '@salesforce/schema/ClientMember__c.Client__r.Client_UID__c';
import CLIENTUID_FIELD2 from '@salesforce/schema/Account.Client_UID__c';

export default class testCreateRecordLWC extends LightningElement {
    handleCreateCM(){
        let clientUIDInput = this.template.querySelector('lightning-input');

        const fields = {};
        fields[CLIENTUID_FIELD.fieldApiName] = clientUIDInput.value;
        
        const recordInput = { apiName: CLM_OBJECT.objectApiName, fields };
        
        createRecord(recordInput)
            .then(cm =>{
                this.dispatchEvent(
                    new ShowToastEvent({
                        title: 'Success',
                        message: 'New ClientMember__c has been created',
                        variant: 'success',
                    }),
                );
            })
            .catch(error => {
                console.log(error);
                this.dispatchEvent(
                    new ShowToastEvent({
                        title: 'Error while creating ClientMember__c',
                        message: error.body.message,
                        variant: 'error',
                    }),
                );
            });
    }
}

I get : POST_BODY_PARSE_ERROR

I also tried this:

const fields = {
    Client__c : clientUIDInput.value
};    

Malformed ID

or this:

const fields = {
      Client__r : {
          Client_UID__c : clientUIDInput.value
      }
};   

Field Client__r has value of unsupported data type:

What do I have to do to achieve this?

Answer 1

If you look at the UI-API, you'll see there's no mechanism for you to do this.

For your attempt, you'll see that createRecord specified what data types the fields parameter supports. For your use case, the only relevant one would be Reference - which would be the lookup field on ClientMember

Format data types according to these rules:

• ...
• Reference—JSON String
• ...

However, Reference expects a record Id. You can quickly test this by importing the lookup field to Account on ClientMember__c and trying to pass the external Id.

"Account ID: id value of incorrect type: 123"

If you try to import the Account's external Id field through the relationship of ClientMember, your request body won't be valid as it expects fields to be a Map<String,Object> where String matches a field name on the object itself (ClientMember)

"errorCode":"POST_BODY_PARSE_ERROR"

Likewise, trying to get the real Account Id by leveraging the external Id won't work as getRecord expects the record Id of a record

"message":"Illegal value for parameter: 'recordId':

"statusCode":400,"errorCode":"INVALID_ID_FIELD"

As such, you can't do what you're trying to do with UI-API - you'll have to call an apex method from your LWC

The good news is that, if you're going to use apex, you can leverage the external Id (no need for Account Id) as shown by Relating Records By Using an External Id

//Pass all your necessary info
Account accountReference = new Account(Client_UID__c = 'yourexternalId');
//create new clientmember record
ClientMember__c newClientMember = new ClientMember(...);
//field name on ClientMember with __r
newClientMember.Client__r = accountReference; 

insert newClientMember;