Introduction to the ADO.NET Entity Framework using ASP.NET - CRUD operations using ADO.NET Entity Framework: Source Code
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This section is a continuation from the previous section. Modify the code behind so that it looks like this:
Public Partial Class CRUD
Inherits System.Web.UI.Page
Protected Sub btnSearch_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnSearch.Click
Dim ctxt As New NorthwindEntities
Dim oEmp As Emp = (From o In ctxt.Emp.Include("Dept") _
Where o.Empno = Me.txtEmpno.Text _
Select o).FirstOrDefault
If oEmp Is Nothing Then
btnClear_Click(Nothing, Nothing)
Me.lblMsg.Text = "Employee not found."
Exit Sub
End If
Me.txtEname.Text = oEmp.Ename
Me.txtSal.Text = oEmp.Sal
Me.txtDeptno.Text = oEmp.Dept.Deptno
End Sub
Protected Sub btnClear_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnClear.Click
Me.txtEmpno.Text = ""
Me.txtEname.Text = ""
Me.txtSal.Text = ""
Me.txtDeptno.Text = ""
Me.lblMsg.Text = ""
End Sub
Protected Sub btnAdd_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnAdd.Click
Try
Dim oEmp As New Emp With {.Empno = Me.txtEmpno.Text, .Ename = Me.txtEname.Text, .Sal = Me.txtSal.Text}
Dim oDeptKey As New EntityKey("NorthwindEntities.Dept", "Deptno", Integer.Parse(Me.txtDeptno.Text))
oEmp.DeptReference.EntityKey = oDeptKey
Dim ctxt As New NorthwindEntities
ctxt.AddToEmp(oEmp)
ctxt.AcceptAllChanges()
ctxt.SaveChanges()
Me.lblMsg.Text = "Added Successfully!"
Catch ex As Exception
If ex.Message.ToLower.Contains("innerexception") Then
Me.lblMsg.Text = ex.InnerException.Message
Else
Me.lblMsg.Text = ex.Message
End If
End Try
End Sub
Protected Sub btnUpdate_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnUpdate.Click
Dim ctxt As New NorthwindEntities
Dim oEmp As Emp = ctxt.Emp.Where(Function(p) p.Empno = Me.txtEmpno.Text).FirstOrDefault
If oEmp Is Nothing Then
Me.lblMsg.Text = "Employee not found to update"
Exit Sub
End If
Dim oDept As Dept = ctxt.Dept.Where(Function(p) p.Deptno = Me.txtDeptno.Text).FirstOrDefault
If oDept Is Nothing Then
Me.lblMsg.Text = "Invalid Deptno"
Exit Sub
End If
oEmp.Ename = Me.txtEname.Text
oEmp.Sal = Me.txtSal.Text
oEmp.Dept = oDept
ctxt.SaveChanges()
Me.lblMsg.Text = "Updated Successfully!"
End Sub
Protected Sub btnDelete_Click(ByVal sender As Object, ByVal e As EventArgs) Handles btnDelete.Click
Dim ctxt As New NorthwindEntities
Dim oEmp As Emp = ctxt.Emp.Where(Function(p) p.Empno = Me.txtEmpno.Text).FirstOrDefault
If oEmp Is Nothing Then
Me.lblMsg.Text = "Employee not found to delete"
Exit Sub
End If
ctxt.DeleteObject(oEmp)
ctxt.SaveChanges()
btnClear_Click(Nothing, Nothing)
Me.lblMsg.Text = "Deleted Successfully!"
End Sub
End Class
Next: Digging a bit more into the ADO.NET Entity Framework >>
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