Hi everyone!

Need help.

I'm need create trigger who will work at @future and callout API from external services.

Here example what I'm write, have custom Object with field "Cover Letter' . Can I update this field in @future after get request from external service:

here is callout with example URL 

public class JobApplicationHttpCalloutForFuture {

    public static HttpResponse calloutCoverLetter(){
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        String apiUrl = 'https://th-apex-http-callout.herokuapp.com/animals';

        request.setEndpoint(apiUrl);
        request.setMethod('GET');

        HttpResponse response = http.send(request);

        return response;
    }

}

Here is trigger helpers methods

 public static void updateCoverLetter(List<Job_Application__c> listJobApplications) {
        Set<Id> jobApplicationsIds = new Set<Id>();

        for (Job_Application__c jobApplication : listJobApplications) {
            if (jobApplication.Cover_Letter__c == null) {
                jobApplicationsIds.add(jobApplication.Id);
            }
        }

        assyncUpdateCoverLetter(new List<Id>(jobApplicationsIds));
    }

    @Future(Callout=true)
    public static void assyncUpdateCoverLetter(List<Id> jobApplicationIds) {
        List<Job_Application__c> jobApplications = [SELECT Id, Cover_Letter__c FROM Job_Application__c WHERE Id IN :jobApplicationIds];
        HttpResponse response = JobApplicationHttpCalloutForFuture.calloutCoverLetter();

        if (response.getStatusCode() == 200) {
            String responseBody = response.getBody();
            List<Job_Application__c> jobApplicationsToUpdate = new List<Job_Application__c>();

            for (Job_Application__c jobApplication : jobApplications) {
                jobApplication.Cover_Letter__c = responseBody;
                jobApplicationsToUpdate.add(jobApplication);
            }

            if (!jobApplicationsToUpdate.isEmpty()) {
                update jobApplicationsToUpdate;
            }
        } else {
            System.debug('Error getting response code ' + response.getStatusCode());
        }
    }

Can Im update field after update ?