Autonumbering in Dynamics365

Autonumber.cs

namespace TransactionPlugin
{
    public class Autonumber : IPlugin
    {
        public void Execute(IServiceProvider serviceProvider)
        {
            var pluginContext = (IPluginExecutionContext)serviceProvider.GetService(typeof(IPluginExecutionContext));
            var factory = (IOrganizationServiceFactory)serviceProvider.GetService(typeof(IOrganizationServiceFactory));
            var service = factory.CreateOrganizationService(null);

            var target = pluginContext.InputParameters["Target"] as Entity;

            var qExpression = new QueryExpression("new_lock");
            qExpression.ColumnSet = new ColumnSet("new_name");
            qExpression.Criteria.AddCondition("new_name", ConditionOperator.Equal, "Counter");
            var results = service.RetrieveMultiple(qExpression);
            var counter = results.Entities.First();
            var blocker = new Entity("new_lock");
            blocker.Id = counter.Id;
            blocker["new_name"] = "Counter";
            service.Update(blocker); //NOW WE LOCK ALL TRANSACTIONS

            var lockedCounter = service.Retrieve("new_lock", blocker.Id, new ColumnSet("new_lastnumber"));

            var currentNumber = lockedCounter.GetAttributeValue<int>("new_lastnumber");

            target["accountnumber"] = $"{++currentNumber}";

            var counterUpdater = new Entity("new_lock");
            counterUpdater.Id = counter.Id;
            counterUpdater["new_lastnumber"] = currentNumber;
            service.Update(counterUpdater);
        }
    }
}