Programmatically managing Microsoft Access Attachment-typed field with .NET

Question

Access added a new data type in the 2007 version--the Attachment type. We are currently working on a WinForms application with .NET 3.5 (C#) that uses an Access 2007 database. We want to be able to add new attachments through the WinForms interface. I can't seem to locate any information on how to insert or select attachment data with .NET. I did try using DAO (version 12) but it didn't seem to have the SaveToFile or LoadFromFile methods discussed here: http://msdn.microsoft.com/en-us/library/bb258184.aspx

So, how can I get at the attachments with .NET?

Answer 1

I finally got this working in C# using a reference to Microsoft.Office.Interop.Access.Dao.

DBEngine dbe = new DBEngine();
Database db = dbe.OpenDatabase("C:\\SomeDatabase.accdb", false, false, "");
Recordset rs = db.OpenRecordset("SELECT * FROM TableWithAttachmentField", RecordsetTypeEnum.dbOpenDynaset, 0, LockTypeEnum.dbOptimistic);
rs.MoveFirst();
rs.Edit();
Recordset2 rs2 = (Recordset2)rs.Fields["AttachmentFieldName"].Value;
rs2.AddNew();

Field2 f2 = (Field2)rs2.Fields["FileData"];

f2.LoadFromFile("C:\\test.docx");
rs2._30_Update();
rs2.Close();

rs._30_Update();
rs.Close();

This will add test.docx to the Attachment field "AttachmentFieldName" in table "TableWithAttachmentField". One thing to note is that attempting to add the same file twice will throw an error.