LWC Wire Method Interview Questions
11. What is a Wire Adapter?
Lightning web components has an elegant way to provide a stream of data to a component. Define a data provider called a wire adapter in lwc. A wire adapter only provides a data.
12. How dynamically data gets updated in Wire methods?
Wire adapters are part of Lightning web component's reactivity system. An @wire adapters takes two parameters, one is the name of a wire adapter and second one is an optional configuration object. You can use a $ to mark the property of a configuration object as dynamic. When a dynamic property’s value changes, the wire method executes with the new value and provides an updated new data, the component get's rerenders to show the changes.
[import { LightningElement, api, wire } from 'lwc';
export default class WireExample extends {
@api accountId;
@wire(getAccount, { id: '$accountId'})
accountInfo;
}]
13. How manually call wire method to update data?
We know that wire provides data, if we are using wire function or wire parameter to display data in front end, that data will not be changed or updated unless input parameters changed which are used in wire. By using refreshApex in lwc we can call wire function or wire parameter data manually, so that wire data gets updated and component will be re-rendered.
[afterUpdate(){
getUpdatedAccounts()
.then(result => {
refreshApex(this.getWiredAccounts); // calling wire method
}).catch(error => {
this.error = error;
});
}]
14. Difference between calling methods via @wire or imperatively?
wire:
- To use apex methods via @wire, you must annotate it with cacheable=true.
- @wire is a reactive. When the wire service gets data, the component re-renders.
- Wire method gets called it self to update data, if the parameter value changes.
- Also call wire methods manually using refreshApex.
Imperative calling:
- To use apex methods via Imperative, no need to annotate it with cacheable=true.
[import { LightningElement, api, wire } from 'lwc';
import { getRecord } from 'lightning/uiRecordApi';
export default class oppRecord extends LightningElement {
@api recordId;
@wire(getRecord, { recordId: '$recordId', fields: ['Opportunity.Name'] })
record;
}]
for more details and example Click here.
16. What is a getPicklistValues wire method?
Use getPicklistValues wire method to get the picklist values for a specified field.
[import { LightningElement, api, wire } from 'lwc';
import { getPicklistValues } from 'lightning/uiRecordApi';
export default class accountRecord extends LightningElement {
@api recordId;
@wire(getPicklistValues , { recordId: '$recordId', fieldApiName: Account.Industry})
record;
}]
for more details and example Click here.
17. What is a getPicklistValuesByRecordType wire method?
Use getPicklistValuesByRecordType wire method to get the values for every picklist of a specified record type.
[import { LightningElement, api, wire } from 'lwc';
import { getPicklistValuesByRecordType} from 'lightning/uiRecordApi';
export default class accountRecord extends LightningElement {
@api recordId;
@wire( getPicklistValuesByRecordType, { objectApiName: 'Account', recordTypeId: '012345000000000AAA' })
record;
}]
18. What is a getObjectInfo wire method?
Use getObjectInfo wire adapter to get metadata of any object. It will return a metadata describing fields, child relationships, record type, themes and more.
[import { LightningElement, api, wire } from 'lwc';
import { getObjectInfo} from 'lightning/uiRecordApi';
export default class accountObj extends LightningElement {
@api recordId;
@wire( getObjectInfo, { objectApiName: 'Account'})
accountInfo;
}]
for more details and example Click here.
19. What is a getListUi wire method?
Use getListUi wire adapter returns the records and metadata for a list view .
[import { LightningElement, api, wire } from 'lwc';
import { getListUi } from 'lightning/uiRecordApi';
export default class accountObj extends LightningElement {
@api recordId;
@wire( getListUi , { objectApiName: 'Account', listViewApiName: 'Banking_Accounts' })
listviewInfo;
}]
20. What is a getRecordUi wire method?
Use getRecordUi wire adapter to get layout information, metadata, and data to build UI for one or more records.
[import { LightningElement, api, wire } from 'lwc';
import { getRecordUi } from 'lightning/uiRecordApi';
export default class accountObj extends LightningElement {
@wire( getRecordUi , { recordIds: ['006455780012345AYC'], layoutTypes: ['Full'], modes: ['View'] })
listviewInfo;
}]
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