11. Modify `getCars()` method to work with Filters

[rodriggj]

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[rodriggj]

We first need to create a wrapper or container Class to enable the current Filter selection properties coming from the carFilter class to be available for the CarController.cls class. Because the filter options are of different data types, we will create a wrapper or container class to pull in the filter properties. This wrapper Class in out CarController.cls file.

1. Open the CarController.cls file and enter the following code. This will create a Filter Object which we will later pass to the getCars() method.

public with sharing class CarController {
    //wrapper class
    public class Filters {
        @AuraEnabled
        public String searchKey {get;set;}
        @AuraEnabled
        public Decimal maxPrice {get;set;}
        @AuraEnabled
        public String[] categories {get;set;}
        @AuraEnabled
        public String[] makeType {get;set;}
    }
    @AuraEnabled(Cacheable=true)
    public static List<Car__c> getCars(Filters filters){

    }
}

[rodriggj]

2. Now that we have the Filter Object in the getCars() method which creates a SOQL Query, we can now use the attributes in the Filter Object and dynamically utilize the Filters that were selected in the UI to modify the response of the SOQL query.

public with sharing class CarController {
    //wrapper class
    public class Filters {
        @AuraEnabled
        public String searchKey {get;set;}
        @AuraEnabled
        public Decimal maxPrice {get;set;}
        @AuraEnabled
        public String[] categories {get;set;}
        @AuraEnabled
        public String[] makeType {get;set;}
    }
    @AuraEnabled(Cacheable=true)
    public static List<Car__c> getCars(Filters filters){
        String key, whereClause ='';
        Decimal maxPrice;
        String[] categories, makeType, criteria = new List<String>{};

        return [SELECT Id, Name, MSRP__c, Description__c, Category__c, Picture_URL__c FROM Car__c];
    }
}

[rodriggj]

3. Here we will execute some conditional logic to ensure that all the properties of the filter Object we intended to pass are captured. With all the properties accounted for, we will assemble a String that executes the SOQL query and return the response from the SOQL query.

public with sharing class CarController {
    //wrapper class
    public class Filters {
        @AuraEnabled
        public String searchKey {get;set;}
        @AuraEnabled
        public Decimal maxPrice {get;set;}
        @AuraEnabled
        public String[] categories {get;set;}
        @AuraEnabled
        public String[] makeType {get;set;}
    }
    @AuraEnabled(Cacheable=true)
    public static List<Car__c> getCars(Filters filters){
        String key, whereClause ='';
        Decimal maxPrice;
        String[] categories, makeType, criteria = new List<String>{};
        if(filters !=null){
            maxPrice = filters.maxPrice;
            categories = filters.categories;
            makeType = filters.makeType;
            if(!String.isEmpty(filters.searchKey)){
                key = '%'+filters.searchKey + '%';
                criteria.add('Name LIKE: key');
            }
            if(filters.maxPrice >= 0){
                criteria.add('MSRP__c <= :maxPrice');
            }
            if(filters.categories != null){
                criteria.add('Category__c IN :categories');
            }
            if(filters.makeType != null){
                criteria.add('Make__c IN :makeType');
            }
            if(criteria.size()>0){
                whereClause =  'WHERE ' + String.join(criteria, ' AND ');
            }
        }
        String query = 'SELECT Id, Name, MSRP__c, Description__c,Category__c, Picture_URL__c FROM Car__c' + whereClause + ' WITH SECURITY_ENFORCED' + ' ORDER BY Name';
        return Database.query(query);
    }
}

[rodriggj]

4. Now there should be an cars array returned from the SOQL query when the getCars(Filter filters) method executes. We can now pass those results back to our carTileList.js file just like we did previously. We already prepared the @wire adaptor, so now we just need to pass the results of the getCars(Filter filters) back to the adaptor by referencing the filters object.

carTileList.js file

import { LightningElement, wire } from 'lwc';
import getCars from '@salesforce/apex/CarController.getCars'

export default class CarTileList extends LightningElement {
    cars
    error
    filters = {}
    @wire(getCars, {filters: '$filters'})
    carsHandler({data, error}){
        if(data){
            console.log(data)
            this.cars = data
        }
        if(error){
            console.error(error)
            this.error = error
        }
    }
}