getNextFireTime of my existing job - quartz-scheduler

Question

I tried Quartz.com documentation & googled for couple for hours...but could not find single good article on how to get Next Job (which is supposr to fire in future).
I am using CronTrigger Expression to Schedule jobs, using VB.net (winforms). jobs works fine...however I would like my users to see when will it FIRE next. I am storing CronExpression in my database, Can I use that Expression to show next Fire Date/Time to my end users? or if there is any other way possible please advise (with a simple samply).
Thanks
Edit
Following Code Returns next job will fire after 12 minutes instead of 20 minute
Dim exp As CronExpression = New CronExpression("0 0/20 * * * ?")
Dim nextFire As String = exp.GetNextValidTimeAfter(DateTime.Now)
MsgBox(nextFire)

Answer 1

You can create a new JobKey
JobKey jobKey = new JobKey(jobName, groupName);
and use the key to fetch the job detail:
var detail = scheduler.GetJobDetail(jobKey);
this is a simple function which does what you're looking for:
private DateTime getNextFireTimeForJob(IScheduler scheduler, string jobName, string groupName = "")
{
JobKey jobKey = new JobKey(jobName, groupName);
DateTime nextFireTime = DateTime.MinValue;
bool isJobExisting = Scheduler.CheckExists(jobKey);
if (isJobExisting)
{
var detail = scheduler.GetJobDetail(jobKey);
var triggers = scheduler.GetTriggersOfJob(jobKey);
if (triggers.Count > 0)
{
var nextFireTimeUtc = triggers[0].GetNextFireTimeUtc();
nextFireTime = TimeZone.CurrentTimeZone.ToLocalTime(nextFireTimeUtc.Value.DateTime);
}
}
return (nextFireTime);
}
It works only if you have one trigger per job.
If there's more than one trigger in your job you can loop through them:
foreach (ITrigger trigger in triggers)
{
Console.WriteLine(jobKey.Name);
Console.WriteLine(detail.Description);
Console.WriteLine(trigger.Key.Name);
Console.WriteLine(trigger.Key.Group);
Console.WriteLine(trigger.GetType().Name);
Console.WriteLine(scheduler.GetTriggerState(trigger.Key));
DateTimeOffset? nextFireTime = trigger.GetNextFireTimeUtc();
if (nextFireTime.HasValue)
{
Console.WriteLine(TimeZone.CurrentTimeZone.ToLocalTime(nextFireTime.Value.DateTime).ToString());
}
}
or using Linq (System.Linq) :
var myTrigger = triggers.Where(f => f.Key.Name == "[trigger name]").SingleOrDefault();

Answer 2

If you already know the cronExpression then you can call GetNextValidTimeAfter , eg
CronExpression exp = new CronExpression("0 0 0/1 1/1 * ? *");
var nextFire = exp.GetNextValidTimeAfter(DateTime.Now);
Console.WriteLine(nextFire);
and if you want more fire times, then
for(int i=0 ; i< 9; i++)
{
if (nextFire.HasValue)
{
nextFire = exp.GetNextValidTimeAfter(nextFire.Value);
Console.WriteLine(nextFire);
}
}
If you are looking for a more general way of showing next fire times for existing jobs, then check out the answer to this question which works even if you aren't using cron expressions. This is for Quartz Version 2
The Quartz Version 1 way of getting job and trigger information is something like the method below.
public void GetListOfJobs(IScheduler scheduler)
{
var query =
(from groupName in scheduler.JobGroupNames
from jobName in scheduler.GetJobNames(groupName)
let triggers = scheduler.GetTriggersOfJob(jobName, groupName)
select new
{
groupName,
jobName,
triggerInfo = (from trigger in triggers select trigger)
}
);
foreach (var r in query)
{
if (r.triggerInfo.Count() == 0)
{
var details = String.Format("No triggers found for : Group {0} Job {1}", r.groupName, r.jobName);
Console.WriteLine(details);
}
foreach (var t in r.triggerInfo)
{
var details = String.Format("{0,-50} {9} Next Due {1,30:r} Last Run {2,30:r} Group {3,-30}, Trigger {4,-50} {5,-50} Scheduled from {6:r} Until {7,30:r} {8,30:r} ",
t.JobName,
t.GetNextFireTimeUtc().ToLocalTime(),
t.GetPreviousFireTimeUtc().ToLocalTime(),
t.JobGroup,
t.Name,
t.Description,
t.StartTimeUtc.ToLocalTime(),
t.EndTimeUtc.ToLocalTime(),
t.FinalFireTimeUtc.ToLocalTime(),
((t.GetNextFireTimeUtc() > DateTime.UtcNow) ? "Active " : "InActive")
);
Console.WriteLine(details);
}
}
}

Answer 3

I had problem where i am getting next execution time even for the date which are past the end time.
Following is my implementation which eventually returning the correct result in Quartz 3.0.4
internal static DateTime? GetNextFireTimeForJob(IJobExecutionContext context)
{
JobKey jobKey = context.JobDetail.Key;
DateTime? nextFireTime = null;
var isJobExisting = MyQuartzScheduler.CheckExists(jobKey);
if (isJobExisting.Result)
{
var triggers = MyQuartzScheduler.GetTriggersOfJob(jobKey);
if (triggers.Result.Count > 0)
{
var nextFireTimeUtc = triggers.Result.First().GetNextFireTimeUtc();
if (nextFireTimeUtc.HasValue)
{
nextFireTime = TimeZone.CurrentTimeZone.ToLocalTime(nextFireTimeUtc.Value.DateTime);
}
}
}
return nextFireTime;
}