為什么出現ConnectionString未初始化錯誤

Question

內容頁：

protected void Page_Load(object sender, EventArgs e)
{
    string gs = ConfigurationManager.ConnectionStrings["ging"].ConnectionString;
    if (Master.showCheck(s))
    {
        //do something...
    }
}

母版頁：

string gs = "";
protected void Page_Load(object sender, EventArgs e)
{
    gs = ConfigurationManager.ConnectionStrings["ging"].ConnectionString;
}
public bool showCheck(string strID)
{
    string strCheckIfParentExist = @"";

    using (SqlConnection scConn = new SqlConnection(gs))
    {
        scConn.Open(); //throws an error: 'The ConnectionString property has not been initialized'
    }
}

為什么會出現以下錯誤： The ConnectionString property has not been initialized

Answer 1

更改

protected void Page_Load(object sender, EventArgs e)
{
    string gs = ConfigurationManager.ConnectionStrings["ging"].ConnectionString;
}
public bool showCheck(string strID)
{
    string strCheckIfParentExist = @"";

    using (SqlConnection scConn = new SqlConnection(gs))
    {
        scConn.Open(); //throws an error: 'The ConnectionString property has not been initialized'
    }
}

至

private string gs = "";
protected void Page_Load(object sender, EventArgs e)
{
    gs = ConfigurationManager.ConnectionStrings["ging"].ConnectionString;
}
public bool showCheck(string strID)
{
    string strCheckIfParentExist = @"";

    using (SqlConnection scConn = new SqlConnection(gs))
    {
        scConn.Open(); //throws an error: 'The ConnectionString property has not been initialized'
    }
}

基本上，變量是通過與調用它的位置不同的方法聲明的，因此您只需將其范圍擴大到該類。

Answer 2

如果您將“ gs”作為班級成員，請將內容頁面更改為

protected void Page_Load(object sender, EventArgs e)
{
    gs = ConfigurationManager.ConnectionStrings["ging"].ConnectionString;
    if (Master.showCheck(s))
    {
        //do something...
    }
}

您所擁有的字符串def隱藏了類成員。