EF6 - No connection string named 'Data Source=…' could be found in the application config file

Question

I'm trying to set a connection string dynamically to the MyDataContext inheriting DbContext and I got this error:

No connection string named 'Data Source=myserver\\mine;Initial Catalog=MyDb;User ID=user1;Password=mypassword;Connect Timeout=300' could be found in the application config file.

Here's what my code look like:

public class DataContext : DbContext, IDataContext, IDataContextAsync
    {
    private readonly Guid _instanceId;

    public DataContext(string nameOrConnectionString)
        : base(nameOrConnectionString)
    {
        _instanceId = Guid.NewGuid();
        Configuration.LazyLoadingEnabled = false;
        Configuration.ProxyCreationEnabled = false;
    }

//and so on...
}

public class MyDataContext : DataContext
{
        public MyDataContext (string nameOrConnectionString)
            :base(nameOrConnectionString)
        {
        }
}

I'm wondering why this is happening. As what I've understand, the constructor can accept either connection string name and connection string. In this case Entity Framework seem to expect a name.

Please help.

Thanks :)

Answer 1

You probably want DbContext(String) and not DataContext(String) given the EF tag (and you referencing nameOrConnectionString argument).

public class MyDataContext : DbContext
{
    public MyDataContext(String nameOrConnectionString)
        : base(nameOrConnectionString)
    {
    }
}

Otherwise the DataContext is looking for a file source, which could be the problem you're seeing.

Answer 2

尝试将连接字符串复制到MVC项目（即主项目）中的.config文件，并确保该MVC项目作为启动。