Automatically enable CAP transaction details in ASP. NET Core

Directory 1. Publisher Transaction 2. Consumer Transaction 1, Create 1 CAP Filter 2, Configure Filter

The purpose of this article is to describe how to use the ASP.NET Core Project and a simple way to enable CAP transactions, because in our examples are more intuitive way of direct demonstration, there is no encapsulation, some beginners students are not very good, find and ask me how to encapsulate, this article is mainly a simple demonstration.

In this example, we are primarily based on the Entity Framework To demonstrate, if you use other Orm principles similar, you can refer to it.

1. Publisher-side transactions

Because most people are in Web You can use it by using the ASP.NET Core Filter way, of course, can also be through middleware, the principle is 1 to.

1. Create a TypeFilter , named CapTransactionFilterAttribute

public class CapTransactionFilterAttribute : TypeFilterAttribute
{
    public CapTransactionFilterAttribute() : base(typeof(TransactionActionFilter))
    {

    }

    public class TransactionActionFilter : IActionFilter
    {
        private IDbContextTransaction _transaction;

        public void OnActionExecuting(ActionExecutingContext context)
        {
            var dbContext = context.HttpContext.RequestServices.GetRequiredService<AppDbContext>();
            var capPublisher = context.HttpContext.RequestServices.GetService<ICapPublisher>();
            _transaction = dbContext.Database.BeginTransaction(capPublisher);
        }

        public void OnActionExecuted(ActionExecutedContext context)
        {
            if (context.Exception == null)
            {
                _transaction.Commit();
            }
            else
            {
                _transaction.Rollback();
            }

            _transaction?.Dispose();
        }
    }
}

2. Usage mode, in the need for transaction control Action Add [ TypeFilter(typeof(CapTransactionFilterAttribute ))] takes effect.

[Route("~/ef/trans-filter")]
[TypeFilter(typeof(CapTransactionFilterAttribute))]
public IActionResult EntityFrameworkWithTransactionFilter(
    [FromServices] AppDbContext dbContext)
{
    dbContext.Persons.Add(new Person() { Name = "ef.transaction" });

    _capBus.Publish("sample.rabbitmq.mysql", DateTime.Now);

    dbContext.SaveChanges();

    return Ok();
}

2. Consumer transactions

Consumer automatic transactions mainly use CAP The provided filter is required to open CAP Version is greater than 5.1. 0.

1. Create an CAP filter

public class MyCapFilter : SubscribeFilter
{
    private readonly AppDbContext _dbContext;
    private IDbContextTransaction _transaction;

    public MyCapFilter(AppDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public override void OnSubscribeExecuting(ExecutingContext context)
    {
        _transaction = _dbContext.Database.BeginTransaction();
    }

    public override void OnSubscribeExecuted(ExecutedContext context)
    {
        _transaction.Commit();
    }

    public override void OnSubscribeException(DotNetCore.CAP.Filter.ExceptionContext context)
    {
       _transaction.Rollback();
    }
}

2. Configure the filter

services.AddCap(opt =>
{
    // ***
}.AddSubscribeFilter<MyCapFilter>();

The above is a simple example of the consumer side.