c# - 允许在 C# 中使用 DateTime.Parse(date.text) 方法传递空值

Question

我有以下表格:

---

一旦我点击按钮，它的工作方式是这样的，所有上述参数都传递给 GetData 方法

protected void btnShow_Click(object Sender, EventArgs e)
{
     ShowReport();
}
private void ShowReport()
{
     //Reset
     ReportViewer1.Reset();

      //DataSource
      DataTable dt = GetData(type.Text, category.Text,subsidary.Text,country.Text, DateTime.Parse(date.Text));
            ............................
}

这是GetData方法

private DataTable GetData(string type, string category, string country, string subsidary, string dateHERE)
{
    // date = date.Value.ToOADate();

    DateTime? mydate = null;
    DateTime date2;
    bool check = DateTime.TryParse(dateHERE, out date2);
    if (check)
    {
        mydate = date2;
    }

    DataTable dt = new DataTable();
    string connStr = System.Configuration.ConfigurationManager.ConnectionStrings["AB_ReportEntities"].ConnectionString;
    using (SqlConnection cn = new SqlConnection(connStr))
    {

        SqlCommand cmd = new SqlCommand("FindIncomplete_Products", cn);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.Add("@type", SqlDbType.NVarChar).Value = type;
        cmd.Parameters.Add("@category", SqlDbType.NVarChar).Value = category;
        cmd.Parameters.Add("@country", SqlDbType.NVarChar).Value = country;
        cmd.Parameters.Add("@subsidary", SqlDbType.NVarChar).Value = subsidary;
        cmd.Parameters.Add("@date", SqlDbType.Date).Value = mydate;

        SqlDataAdapter adp = new SqlDataAdapter(cmd);

        adp.Fill(dt);
    }

    return dt;
}

当日期字段在上面的表单中有空值时，我无法得到结果，我收到以下错误:

System.FormatException: String was not recognized as a valid DateTime.

Answer 1

像这样改变你的方法:

private DataTable GetData(string type, string category, string country, string subsidary,string date)
{
     DateTime? mydate = null;
     DateTime date2;
     bool check = DateTime.TryParse(date, out date2);
     if (check)
     {
         mydate = date2;
     }
}

然后这样调用它:

DataTable dt = GetData(type.Text, category.Text,subsidary.Text,country.Text, date.Text);