objects being null even after calling SatisfyImportOnce - MEF

Question

In my program I am using the following statements in program.cs

    Application.EnableVisualStyles();
    Application.SetCompatibleTextRenderingDefault(false);
    var init = new Initializer();
    var container = new CompositionContainer(new DirectoryCatalog(Environment.CurrentDirectory));
    container.ComposeExportedValue(string.Empty);
    container.SatisfyImportsOnce(init);
if (init.PreleminaryCheck())
            {
                Form1 frm = new Form1();
                container.SatisfyImportsOnce(frm);
                Application.Run(frm);
            }

I am exporting class like below

[Export(typeof(DatabaseMaster))]
    public class DBManager : DatabaseMaster
[ImportingConstructor]
        public DBManager(string filepath = "")

        {
            DbPath = filepath;
        }

The problem is i am only getting the variable initialized in the Initializer class, In the form class the instance of DBManager is always null. I tried calling SatisfyImportOnce on Form1 variable but no luck.

Answer 1

我通过将成员函数调用从构造函数移到form load方法来解决了这个问题，