how to determine current tenant in the distributedEventBus

[fenggaoyao]

1. IDistributedEventHandler is different from mvc, it does not go through middleware, such as .UseMiddleware<MultiTenancyMiddleware>. So the DbContext uses the current host ,
   , Such as BlogUserSynchronizer in the Volo.Blogging module, it can only handle the host,
   If you need to handle tenant,do we need to add _currentTenant.Change(**),like this

  public async Task HandleEventAsync(EntityUpdatedEto<UserEto> eventData)
        {
            using (_currentTenant.Change(eventData.Entity.TenantId))
            {
                var user = await UserRepository.FindAsync(eventData.Entity.Id);
                if (user == null)
                {
                    user = await UserLookupService.FindByIdAsync(eventData.Entity.Id);
                    if (user == null)
                    {
                        return;
                    }
                }
                if (user.Update(eventData.Entity))
                {
                    await UserRepository.UpdateAsync(user);
                }
            }          
        }

2. Volo.Abp.Domain.Entities.Events.Distributed.EntityEto, it does not include tenantId, do we noed to add tenantId?

[maliming]

The entity's TenantId may be different from the current TenantId.
We can consider providing TenantId in the event. Developers can also customize this TenantId.

@hikalkan What do you think?

[hikalkan]

1. You're definitely right. We should store TenantId in the event data and switch to the tenant in the event handler. We can consider to handle it in the framework side (like if the ETO implements IMultiTenant, we can switch to the tenant before calling the handleevent method).
2. I don't think so, because not all entities are multi-tenant. If your entity is multi-tenant, then implement IMultiTenant for the ETO.

[fenggaoyao]

thanks
1、EntityUpdatedEto<UserEto>, as the main synchronization example of distributedeventbus in the framework.but it is hard to use.UserEto should implements IMultiTenant.And when an update IdentityUser, more than 6 times events handle action will be triggered.and Each UserEto is different。I think it Caused by IdentityRoleStore's AutoSaveChanges。It should be as UnitofWork, can AutoSaveChanges be Changed to false and test this

2、Volo.Abp.Domain.Entities.Events.Distributed.EntityEto, as a general Eto, it has extensible Properties. If If your entity is multi-tenant. can add to this in the framework
EntityToEtoMapper.

public object Map(object entityObj)
        {
            ......
            var etoMappingItem = Options.EtoMappings.GetOrDefault(entityType);
            if (etoMappingItem == null)
            {
                var keys = entity.GetKeys().JoinAsString(",");
                var eto = new EntityEto(entityType.FullName, keys);
                 // add this
                if (entityObj is IMultiTenant multitenantEntity)
                {
                    eto.Properties.Add("tenantid",multitenantEntity.TenantId);
                }
                return eto;
            }  
          ....         
        }

[gdlcf88]

It will be a big change. I always inject the ICurrentTenant and change the current tenant to MyOwnEto.TenantId.

[hikalkan]

1 was done with #4433
I didn't like the solution 2. Simply implement IMultiTenant for the ETO. For generic ETOs (like EntityUpdatedEto<T>) the framework can also check the T.

[gdlcf88]

Simply implement IMultiTenant for the ETO

Does it mean that If MyEto class implements IMultiTenant, the IDistributedEventHandler<EntityUpdatedEto<MyEto>> will automatically change the current tenant Id to MyEto.TenantId?

[hikalkan]

Does it mean that If MyEto class implements IMultiTenant, the IDistributedEventHandler<EntityUpdatedEto> will automatically change the current tenant Id to MyEto.TenantId?

Yes, it means that.

[hikalkan]

@maliming can you work on that in this milestone

If the ETO implements IMultiTenant, we can switch to the tenant before calling the handleevent method.

Also consider this scenario:

Does it mean that If MyEto class implements IMultiTenant, the IDistributedEventHandler will automatically change the current tenant Id to MyEto.TenantId