Difference between PreConfigureServices and ConfigureServices

Question

I'm using the ABP framework with multiple modules and need to run join queries on a single DbContext. When I attempted to replace the DbContext of all modules with a single one from the main app in ConfigureServices, it didn't work and showed the following error.

[ERR] Cannot use multiple context instances within a single query execution. Ensure the query uses a single context instance. However, when I added the code in PreConfigureServices, it worked. Why does configuring the DbContext in PreConfigureServices make a difference compared to ConfigureServices in the ABP framework?

    context.Services.AddAbpDbContext<MyDbContext>(options =>
    {
        options.AddDefaultRepositories(includeAllEntities: true);

    });

I want to know the actual reason, why didn't it work on ConfigureServices.

Answer 1

You can find the differences between ConfigureServices and PreConfigureServices methods in this documentation, but here are some important differences:

The ConfigureServices method is where you need to add your services into the DI container, configure options, and perform other service-related configurations.

On the other hand, the PreConfigureServices method is used to make your registrations just before the ConfigureServices method is run. This means it allows you to perform any necessary configuration or setup before the standard service configuration process begins. (Typically, you might use this method to configure certain services or settings that need to be in place before the rest of the application services are configured.)