是否可以对未知数据库表使用实体框架？

Question

User selects a database and its table, and will browse the table in a web application. Can I achieve that with Entity Framework? I know EF is ORM framework but in this case, I may not create edmx file for each selection. Even if I did it, how do I create, say, POCO objects dynamically according to the table? What should I do in this case? Do I have to go with low-level ADO.NET?

Answer 1

I think Entity Framework is unnecessary in this case. It might certainly be possible to use EF for something like this, but if it's a simple case of just getting a list of available table names from the database, and letting the user select a table to view, I would simply do the following:

Create drop down list on the site, and populate it using result from query:

SELECT table_name FROM INFORMATION_SCHEMA.TABLES t

Then after the user selects an item from the dropdown, you can bind your grid using Ado.net. Something like:

string tableName = "get value from dropdown";  
DataTable dt = new DataTable();

using (SqlConnection conn = new SqlConnection("connection string here"))
{
    string sql = string.Format("select * from {0}", tableName);
    SqlDataAdapter da = new SqlDataAdapter(sql, conn);
    da.Fill(dt);
}

// bind dt to your grid or gui component here.

Answer 2

Edit Well I know you can do this at least partially. You can definitely let the user select a database/table because you can provide your own connection string/EntityConnect object to the Contexts constructor. I'm not sure how you can go about creating entities dynamically though, I think you would have to have an edmx file that already has all the entities generated or write them yourself from before.

Answer 3

您必须首先将EF指向每个数据库，而不是期望EF动态地查看应用程序中的新数据库。