C＃中带有dll文件的实体框架

Question

I am new to entity framework. I am creating a module that have to interact with database. The module will be general so it can be referenced in different projects. As those projects will have different databases so the confusion is that how I will get reference to that database in my library as it is going to be different each time?

For explaining purpose, if I shall be using sqlConnection then it will like

class myClass
{
   SqlConnection con;
   public myClass(SqlConnection con)
   {
       this.con=con;
   }

   public DataTable DoSomething()
   {
       try
       {
           connection.open();
           using (SqlDataAdapter com= new SqlDataAdapter("Select * from table1",con))
           {
               DataTable temp = new DataTable();
               com.SelectCommand.ExecuteNonQuery();
               com.Fill(temp);
               return temp;
           }
        }
        catch (Exception ex) {}
    }
}

Answer 1

如果使用EF，则数据库结构（数据上下文）应该（在共享项目之间）相同（除非为每个项目定义单独的数据上下文），否则连接字符串可以保存在配置文件中（对于每个单独的项目）。

Answer 2

You can implement EF Code First in a Class Library Project. Each other project that uses the model will have a reference to that project. Since each project will have its own database then each project has to have its own connection string, you can place this in the app.config file. Entity framework will add something like the following to your app.config in your class library project:

<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework">
  <parameters>
    <parameter value="Your Connection string" />
  </parameters>
</defaultConnectionFactory>
<providers>
  <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>

The only thing you have to do or at least what I did and worked for me is to add entity to your other projects and change your connection string for each one of those.

Hope this helps