Question

I’m using Visual Studio 2008, SQL Server 2008, asp.net mvc 2.

Now, I have to change my database to postgresql. I tried many ways. But I did something different.

1. I created the data model based on SQL Server 2008 database.
2. I have the same structured database in postgresql.
3. So I just changed the connection string of the entity data model and I got the following error

The ‘System.Data.SqlClient’ provider from the specified SSDL
artifact(s) does not match the expected ‘Npgsql’ provider from the
connection string.

How do I solve this error.

Please let me know if this is correct way to implement.

Answer 1

Well, the physical layer of your model (the “SSDL” file in your metadata) will of course contain the physical aspects of your database model – including the database provider that this model is based on. You cannot just simply change the database connection string and be done with that…..

I see two options:

1. my preferred solution: just re-create the EF model based on your Postgres database – that’s the cleanest way to go. If you’re doing it right, this is contained in a single assembly in your project anyway, so you could more or less swap in a new assembly to go against Postgres instead of SQL Server

2. a hack in my opinion: you could have the metadata files (the *.ssdl, *.msl, *.csdl) for your model written out to disk, and then manually edit the SSDL file to switch to the Postgres provider. I have no idea if that will even work and what side-effects it might have! Do at your own risk, and do it on a backup copy of your project first!