C#C
C#•2y ago
M B V R K

Why Events Inserted Twice by EF Core?

Hi guys hope you're doing well,
I'm working on the following project : https://github.com/MbarkT3STO/ExpenovaApp
This project implemented using 
Microservices Architecture

I have a service called 
Event-Sourcerer Service
, this service is responsible about applying 
event-sourcing
 for others services databases records, of course this services communicate with others using 
RabbitMQ
 and 
MassTransit
.
You can take a look on that service here : https://github.com/MbarkT3STO/ExpenovaApp/tree/main/Source/EventSourcererService

This service contains some 
Message Consumers
 ( classes where each one responsible to consume/handle a specific 
Queue
's messages ).
This service uses 
EF Core
 with 
PostgreSQL
 as data persistence.
After a 
Servie X
 published an 
Event
 that happened in it, and the 
Event Handler
 from that 
Service X
 will publish a copy of that event as a 
Message
 to 
RabbitMQ
 then the 
Consumers
 from the 
Event-Sourcerer Service
 will do their job by adding the message they are responsible for into the 
Event-Sources
 database.


The issue: Is my consumers adding the event to database twice
To fix this issue I have created a service to handle the 
Deduplication mechanism
 as separated class called 
DatabaseMessageDeduplicationService
 you could take a look at it here : https://github.com/MbarkT3STO/ExpenovaApp/blob/main/Source/EventSourcererService/Services/DatabaseMessageDeduplicationService.cs

That class 
DatabaseMessageDeduplicationService
 is responsible about processing messages too.
So, for proccessing messages this class contains a method called 
ProccessMessage
 as following:
    public async Task ProcessMessage(Expression<Func<Task>> processMessageFunc)
    {
        await processMessageFunc.Compile().Invoke();
    }

This method take a 
func
/method from a 
consumer
, that method consumer will contains the code to process the message and this 
DatabaseMessageDeduplicationService
 only invoking it.
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