Using LINQ with Multiple DbContexts in ABP Framework #7833

IbrahimSarigoz created 6 months ago

Hello;

I have two projects: ModuleA and DemoCenterApp. DemoCenterApp can use ModuleA.

ModuleA contains an entity named Iletisim. DemoCenterApp contains an entity named Musteri.

The databases of both projects are different.

In DemoCenterAppDbContext, I used [ReplaceDbContext(typeof(IModuleADbContext))] and added:

public DbSet&lt;Iletisim&gt; Iletisims { get; set; }

My problem is that I want to perform a single LINQ query in EfCoreMusteriRepository that includes Iletisim.

However, I am getting the following error:

Cannot use multiple context instances within a single query execution. Ensure the query uses a single context instance. System.InvalidOperationException: Cannot use multiple context instances within a single query execution. Ensure the query uses a single context instance.

I followed the method described in this YouTube video. As mentioned there, isn't using ReplaceDbContext sufficient?

ABP Framework version: v8.2.2
UI Type: Angular / MVC
Database System: EF Core (Oracle)
Tiered (for MVC) or Auth Server Separated (for Angular): yes

maliming created 6 months ago

Support Team Fullstack Developer

The databases of both projects are different.

What does that mean?

ModuleA is a module, why is has use a database?

IbrahimSarigoz created 6 months ago

https://blog.antosubash.com/posts/abp-add-new-module-with-seperate-db

Our requirement is this: we have a large project with separate CRM and ERP modules, each with its own database. I want to use these modules' DbContexts in my central application, but we couldn't connect two different DbContexts in the same LINQ query. However, a YouTube video suggests it's possible. How can this be achieved?

maliming created 6 months ago

Support Team Fullstack Developer

but we couldn't connect two different DbContexts in the same LINQ query.

I don't think this can be done.

https://github.com/dotnet/efcore/issues/32872#issuecomment-1910570373

IbrahimSarigoz created 6 months ago

[ReplaceDbContext(typeof(IIdentityProDbContext))] [ReplaceDbContext(typeof(ISaasDbContext))]

As you can see in the image, the first method results in an error because the audit tables use a different DbContext. However, the second method works successfully. So, why are we using ReplaceDbContext ?

alper created 6 months ago

ABP Core Team

Hi @IbrahimSarigoz,

Did you use the same interface in your EfCoreIletisimRepository? It should like;

public class EfCoreIletisimRepository : EfCoreRepository<IModuleADbContext, Iletisim, Guid>, IIletisimRepository
{
    public EfCoreIletisimRepository(
        IDbContextProvider<IModuleADbContext> dbContextProvider) 
        : base(dbContextProvider)
    {
    }
}

Lastly don't forget the add repository to your ModuleNameEntityFrameworkCoreModule class.

public class ModuleAEntityFrameworkCoreModule : AbpModule 
{
    public override void ConfigureServices(ServiceConfigurationContext context)
    {
        context.Services.AddAbpDbContext<ModuleADbContext>(options =>
        {
            options.AddRepository<Iletisim, EfCoreIletisimRepository>();
        });
    }
}

IbrahimSarigoz created 6 months ago

I completed all of these. If you want, I can share the github repo with you.

alper created 6 months ago

ABP Core Team

No need, I created a sample application that you can check out in abp-samples. Before testing it, make sure to build the entire solution using the dotnet build command. Afterward, you can debug the SampleRepositoryTests in the EntityFrameworkCore.Tests project.

IbrahimSarigoz created 6 months ago

Hello, thank you for your response

Currently, when the 'Contact' entity is in the same database and tablespace, everything works fine. However, we need to use a separate tablespace for this entity (module). When I create a different tablespace and attempt to use this entity in linq, I encounter the following error:

'Cannot use multiple context instances within a single query execution. Ensure the query uses a single context instance.' System.InvalidOperationException: 'Cannot use multiple context instances within a single query execution. Ensure the query uses a single context instance.

I did some research, and they say it doesn't work with different tablespaces or databases in one linq. I want to make sure that it also doesn't work in the ABP framework.