How to call the imperative apex method from connectedCallback() in LWC?
I want to call an imperative method in connectedCallback() because at the time of lwc loading I want to prepopulate some data into lwc.
I am returning wrapper class data from the apex. Trying the below snippet of code to get that in js but in error also not able to get anything.it's not going to result at all. Can anyone help me through this?
APEX :
@AuraEnabled public static personDataWrapper getPersonTimeZone(Id loanReqId) { Loan_Request__c lr = [ select Id, Name, Leads__c, Account__c, Account__r.Name, Leads__r.Timezone__c, Leads__r.FirstName, Leads__r.LastName, Status__c from Loan_Request__c where Id =:loanReqId ]; personDataWrapper pdw = new personDataWrapper(); if(lr.Leads__c != NULL){ pdw.personName = lr.Leads__r.FirstName + ' ' + lr.Leads__r.LastName; }else{ pdw.personName = lr.Account__r.Name; } pdw.timezoneValue = lr.Leads__r.Timezone__c; pdw.loanRequestName = lr.Name; pdw.currentDt = system.now().adddays(1); if (lr.Status__c.contains('Closed')) { pdw.isLRClosed = true; } else { pdw.isLRClosed = false; } return pdw; } public class personDataWrapper { @AuraEnabled public String personName { get; set; } @AuraEnabled public String timezoneValue { get; set; } @AuraEnabled public String loanRequestName { get; set; } @AuraEnabled public Boolean isLRClosed { get; set; } @AuraEnabled public DateTime currentDt { get; set; } }
LWC :
connectedCallback() { console.log('In connected call back function....'); getPersonZone({loanReqId: this.recordId}) .then(result => { console.log(result.records[0].personName); /* console.log('In connected call back result....'); this.loanrequestdata = result; console.log('The loanrequestdata ' + this.loanrequestdata); console.log( '==result.Leads__r.FirstName===' + loanrequestdata.personName); this.timeZone = this.loanrequestdata.timezoneValue; if (this.loanrequestdata.personName != null && this.loanrequestdata.personName != '') { this.title = 'Callback for Loan Inquiry ' + this.loanrequestdata.personName; } this.dateTimeFieldValue = this.loanrequestdata.currentDt;*/ }) .catch(error => { console.log('In connected call back error....'); this.error = error; console.log('Error is ' + this.error); }); }
Template :
To call imperative apex method from connectedCallback() in LWC -
Here's the culprit: console.log(result.records[0].personName);getPersonTimeZone returns a single instance of personDataWrapper class, which doesn't have a records property, so doing result.records[0] you're trying to access an undefined parameter, thus the exception.
By the way, console.log() takes a list of objects to output, so there is no need to concatenate them as string, you could and should pass them as different parameters so you'll never see again [object Object]. The same goes for console.info(), console.warn(), console.error() and so on.
connectedCallback() { console.log('In connected call back function....'); getPersonZone({loanReqId: this.recordId}) .then((result) => { console.log(result.personName); /* console.log('In connected call back result....'); this.loanrequestdata = result; console.log('The loanrequestdata ' + this.loanrequestdata); console.log('==result.Leads__r.FirstName===' + loanrequestdata.personName); this.timeZone = this.loanrequestdata.timezoneValue; if (this.loanrequestdata.personName && this.loanrequestdata.personName.length > 0) { this.title = 'Callback for Loan Inquiry ' + this.loanrequestdata.personName; } this.dateTimeFieldValue = this.loanrequestdata.currentDt;*/ }) .catch((error) => { console.log('In connected call back error....'); this.error = error; // This way you are not to going to see [object Object] console.log('Error is', this.error); }); }
Answer (1)
To call an imperative Apex method from the connectedCallback() in Lightning Web Component (LWC), follow these steps:1. Import the Apex Method
First, you need to import the Apex method in your LWC JavaScript file. Use the @salesforce/apex module to do this.
import { LightningElement, track } from 'lwc';
import getApexData from '@salesforce/apex/YourApexController.getApexData';
2. Implement connectedCallback()
In your LWC JavaScript file, define the connectedCallback() lifecycle hook. Inside this method, call the imported Apex method imperatively using JavaScript then and catch promises.
connectedCallback() {
this.fetchData();
}
fetchData() {
getApexData()
.then(result => {
// Handle the result
console.log('Data received:', result);
})
.catch(error => {
// Handle the error
console.error('Error:', error);
});
}3. Handle Data and Errors
In the .then block, you process the data returned from the Apex method. In the .catch block, handle any errors that occur during the call.
Example Implementation
Here is a complete example:
JavaScript (yourComponent.js)import { LightningElement, track } from 'lwc';
import getApexData from '@salesforce/apex/YourApexController.getApexData';
export default class YourComponent extends LightningElement {
@track data;
@track error;
connectedCallback() {
this.fetchData();
}
fetchData() {
getApexData()
.then(result => {
this.data = result;
console.log('Data received:', result);
})
.catch(error => {
this.error = error;
console.error('Error:', error);
});
}
}HTML (yourComponent.html)
HTML (yourComponent.html)
Notes
Ensure that your Apex method is annotated with @AuraEnabled(cacheable=true) if you intend to cache the result.
Handle both the data and potential errors appropriately to ensure a good user experience.
By following these steps, you can successfully call an imperative Apex method from the connectedCallback() in your LWC.