Define and schedule jobs

Understanding IJob

In NCronJob, jobs are defined by implementing the IJob interface. This interface contains a single method, RunAsync, where you define the task’s execution logic.

NCronJob registers IJob implementations as scoped services within your application’s dependency injection container. This means that a new scope is created for each job execution, ensuring isolation and allowing for clean dependency management (particularly important when working with frameworks like Entity Framework Core).

Defining a Job

Follow these steps to create and schedule a job in NCronJob:

public class MyCronJob : IJob 
{
    private readonly ILogger<MyCronJob> _logger;

    public MyCronJob(ILogger<MyCronJob> logger)
    {
        // MyCronJob lives in the container so you can inject services here
        _logger = logger;
    }

    public Task RunAsync(IJobExecutionContext context, CancellationToken token)
    {
        _logger.LogInformation("MyCronJob is executing!");

        // Add your job logic here (e.g., database updates, sending emails, etc.)

        return Task.CompletedTask;
    }
}

Registering the Job

using NCronJob;

// Inside your service configuration
Services.AddNCronJob(options => 
{
    options.AddJob<MyCronJob>(j => 
    {
        j.WithCronExpression("*/5 * * * *"); //  Runs every 5 minutes
    });
});

Chaining Cron Expressions with And

Execute the same job on multiple schedules using the And command:

Services.AddNCronJob(options => 
{
    options.AddJob<MyCronJob>(j => 
    {
        j.WithCronExpression("0 8 * * *")  // Every day at 8:00 AM
         .And
         .WithCronExpression("0 20 * * *"); // Every day at 8:00 PM 
    });
});

Info

Defining multiple identifical schedules for the same job will not lead to multiple instances of the job running concurrently. NCronJob will ensure that only one instance of the job is running at any given time. One can define different custom names for each schedule to differentiate between them. See “Defining job names”.

The following example illustrates how to define multiple schedules that are identical and will only lead to one instance of the job running at any given time:

Services.AddNCronJob(options => 
{
    options.AddJob<MyCronJob>(j => 
    {
        j.WithCronExpression("0 20 * * *")
         .And
         .WithCronExpression("0 20 * * *");
    });
});

Scheduling Jobs With Time Zones

The library offers you the ability to schedule jobs using time zones.

Services.AddNCronJob(options => 
{
    var timeZone = TimeZoneInfo.FindSystemTimeZoneById("Pacific Standard Time"); 
    options.AddJob<MyCronJob>(j => 
    {
        j.WithCronExpression("0 15 * * *", timeZoneInfo: timeZone); // Every day at 3:00 PM PST
    });
});