我试图提供我正在处理的问题的简化版本。查询1被枚举并返回namespace Calculator
{
public partial class Form1 : Form
{
Double value = 0;
String operation = "";
bool operation_pressed = false;
public Form1()
{
InitializeComponent();
}
// Handler for buttons
private void button_Click(object sender, EventArgs e)
{
// I made this because it's simpler, than making 10 methods for each number
// When you click on button
// The label will check which button did you press
if ((result.Text == "0") || (operation_pressed)) // Clearing the zero on the beginning or when we used one operation
result.Clear();
operation_pressed = false;
Button b = (Button)sender; // Capturing which button was pressed
if (b.Text == ".")
{
if (!result.Text.Contains("."))
{
result.Text = result.Text + b.Text;
}
}
else
result.Text = result.Text + b.Text;
}
private void button18_Click(object sender, EventArgs e)
{
result.Text = "0"; // CE button reset the result back to 0
}
// Handler for operators
private void operator_click(object sender, EventArgs e)
{
Button b = (Button)sender; // Capturing which button was pressed
if (value != 0)
{
if (b.Text == "√")
//result.Text = Math.Sqrt(Double.Parse(result.Text)).ToString();
result.Text = Operators.sqrt(Double.Parse(result.Text)).ToString();
else
{
equal.PerformClick(); // Instead of pressing equals button everytime when we press our second + button it will be calculated
operation_pressed = true;
operation = b.Text;
equation.Text = value + " " + operation; // To see what you have typed in before
}
}
else if (b.Text == "√") // Checking if the square root button was pressed
{
//result.Text = Math.Sqrt(Double.Parse(result.Text)).ToString();
result.Text = Operators.sqrt(Double.Parse(result.Text)).ToString();
value = Math.Sqrt(Double.Parse(result.Text));
}
else
{
operation = b.Text;
value = Double.Parse(result.Text);
operation_pressed = true; // When we use the operator to reset the first number ,
//so we can use new number
equation.Text = value + " " + operation; // To see what you have typed in before
}
}
private void button16_Click(object sender, EventArgs e)
{
equation.Text = ""; // When we press the button equals, we only get the result.
switch (operation)
{
case "+":
//result.Text = (value + Double.Parse(result.Text)).ToString();
result.Text = Operators.Add(value, Double.Parse(result.Text)).ToString();
break;
case "-":
result.Text = Operators.Sub(value, Double.Parse(result.Text)).ToString();
break;
case "*":
result.Text = Operators.Mult(value, Double.Parse(result.Text)).ToString();
break;
case "/":
result.Text = Operators.Div(value, Double.Parse(result.Text)).ToString();
break;
default:
break;
} // end switch
value = Int32.Parse(result.Text); // Converting string to double
operation = ""; // Resetting the operators to empty string
}
private void button17_Click(object sender, EventArgs e)
{
result.Text = "0"; // When you click the button C the result will be set to 0
value = 0; // Everything stored in value will be reset.
equation.Text = ""; // Resetting the equation we did before
}
// Method from capturing numbers from your notebook/pc so you don't have to select them evertyime
// You can type them with your keyboard
private void Form1_KeyPress(object sender, KeyPressEventArgs e)
{
// MessageBox.Show(e.KeyChar.ToString()); // When we press the button it shows use the value of the button
switch (e.KeyChar.ToString())
{
case "0":
zero.PerformClick();
break;
case "1":
one.PerformClick();
break;
case "2":
two.PerformClick();
break;
case "3":
three.PerformClick();
break;
case "4":
four.PerformClick();
break;
case "5":
five.PerformClick();
break;
case "6":
six.PerformClick();
break;
case "7":
seven.PerformClick();
break;
case "8":
eight.PerformClick();
break;
case "9":
nine.PerformClick();
break;
default:
break;
}
}
}
}
List。
但是，当我更改查询并在select语句之前添加PersonViewModel时，查询将返回值.ToList()。
原因是因为我想首先枚举它，所以我可以处理内存中的值 - 以便使用无法转换为SQL的null等函数。
按预期退货
.toString返回var query = (from s in context.PersonDetails.GetQueryable(x => x.Id == Id)
select new PersonViewModel
{
Name = s.Person.Firstname,
Number = s.Person.Number
}).ToList();
null