我正在尝试使用Visual Studio .Net 2013社区版的Entity Framework 6.1.3。问题是没有创建数据库,DBSet类型的属性总是设置为Nothing。
这是我的班级
Public Class ExpenseType
Public Property ExpensTypeId As Integer
Public Property ExpenseName As String
Public Property IsOutgoing As Boolean
End Class
这是我的上下文类
Imports System.Data.Entity
Public Class ExpensesContext
Inherits DbContext
Public Property ExpenseTypes As DbSet(Of ExpenseType)
End Class
这是我的表单代码
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Using db As New ExpensesContext
Dim expensetype As New ExpenseType With
{
.ExpensTypeId = 0,
.ExpenseName = "ADDITIONAL FUND",
.IsOutgoing = False
}
**** value of ExpensesTypes is Nothing and generates NullReferenceException
db.ExpenseTypes.Add(expensetype)
db.SaveChanges()
End Using
End Sub
我的连接字符串(在App.Config中)
<connectionStrings>
<add name="ExpensesContext"
connectionString="Server=localhost;Integrated Security=SSPI;Database=ExpensesTracking"
providerName="System.Data.SqlClient"/>
</connectionStrings>
请帮忙。
提前致谢。
答案 0 :(得分:0)
解决。我忘了将PROPERTY放在DBSet变量中。