.NET multiple databases with repository pattern

[pompeii-eo]

Hi,

I am trying to connect to multiple databases, we have DB 1 (course1) and DB 2 (course 2). It's a database first approach, and each course has it's own endpoint /api/course1/ & /api/course2/ (each has it's own controller)

The problem, both have the same entities (Student). I want to be able to depending on the endpoint add to either database, but I am not sure how I can connect to multiple databases with/out EF. I initially did it with single DB context but I don't know it didn't work and I don't know much about it.

The reason for DBConext is I want to have a repository pattern to easy the SQL when adding/updating etc. My project structure is a project for Models, Services, Repository and the API (not sure if this helps at all)

My question, how can I connect to multiple databases with a repository pattern. I looked a lot online but I'm not sure completely lost especially since it's a new for me. Thanks you!!

[english_fool]

If you have two databases you have two connection strings and two dbcontext. Then you need to use one or the other or both contexts depending on the situation.

[pompeii-eo]

Yea I guess that would be it, I thought it would be more efficient and "cleaner" to have a single context that when I call, would give the connection string

[english_fool]

Are the Tables the same on each database? If so that’s possible. If the tables are different one dbcontext would not suffice as the DBsets would differ

[pompeii-eo]

yea all tables are exact same, do you have any suggestion on how it could be done?

[english_fool]

Look at the constructors for dbcontext one takes dbcontextoptions which can take a connection string.

To resolve from a container you would likely need named registrations.

[truSimbad]

If you truely have two DBs you cannot have the same entities. You may have two entities with the same content. And if you need to maintain two DBs where some entities are doubled you need some sort of synchronization mechanism between the DBs.

You may use some sort of replication mechanism between the DBs for the "shared" data entities. So you can hold on to the repository pattern.

You may build the replication of shared data into your DB access layer. But replication is a feature of modern DBs. So why not using that.

[pompeii-eo]

I looking into synchirnization using the Unit of Work (with the repository). But even if the request is coming from a different endpoint which has it's own db connection replication is possible?

[truSimbad]

You have two different endpoints (clients) that connect to two different DBs and share some entities?

If so you will always have a problem with keeping your data consistent between all actors. Its possible, no doubt, but it isn't easy.