实体框架DbContext与不同的数据库兼容

Question

Using Entity Framework, I have created an application which is able to read data from the database it was modeled against. I now have another database, with the same tables, hosted on another server.

The problem is that the tables on the second database belong to a schema with a different name to the original, so simply changing the connection string for my context in the app.config file doesn't work. (I get the error "table or view does not exist"). There must be some mapping somewhere in the auto generated code stating the original schema name.

What is the correct way to handle this kind of situation? I don't really want to have to re-model the second database as it is identical to the first. I can't change the databases as other applications would stop working.

Any nudge in the right direction would be greatly appreciated.

Answer 1

OK, so here's what I've done to solve this.

As @Kelmen mentioned in the comments, opening the EDMX file in a text editor revealed that this is where the schema information is stored. So I think I could have simply cleared out the value of the schema attribute and used the connection string to drive the schema.

This didn't feel right for a couple of reasons:

1. If the model was refreshed at any point, it might have repopulated the schema names, which would be REALLY annoying. I didn't have time to test if this would actually happen.

2. This method wouldn't let me control the schema name if I did need to change it at runtime.

The solution was to use Code First and the Fluent API to edit the model configuration in the OnModelCreating event within my derived DbContext class.

I'm now considering modifying my context class so that I can pass in the name of the schema or possibly drive it from my app.config.

I found the links tutorials to be quite useful:

Change Schema of Entity Framework

Entity Framework Change Schema Name Per Connection