带表达式值的ASP.NET自定义表达式 [英] ASP.NET Custom Expression with expression values

问题描述

如何动态地将值添加到$ expression？

例如，我想获取用户在两个不同文本框中输入的2个值，并将它们添加为RandomNumber的值（我自己创建的$ Expression） 

< asp：Literal ID =" Literal1" RUNAT = QUOT;服务器" Text ="<％$ RandomNumber：<％= Num1％>，<％= Num2％>％>" /> 

 public string Num1 
 {
 get 
 {
 return TextBox1.Text; 
} 
} 
 
公共字符串Num2 
 {
 get 
 {
 return TextBox2.Text; 
} 
} 

编辑：我也尝试将属性设置为int但仍然不会进行替换...

 public class RandomNumberExpressionBuilder：System.Web .Compilation.ExpressionBuilder 
 {
 public static string GetRandomNumber（int lowerLimit，int higherLimit）
 {
 Random random = new Random（）; 
 int no = random.Next（lowerLimit，higherLimit）; 
返回no.ToString（）; 
} 
公共覆盖CodeExpression GetCodeExpression（BoundPropertyEntry条目，对象parsedData，ExpressionBuilderContext上下文）
 {
 if（！entry.Expression.Contains（"，"））
抛出新的ArgumentException（"必须通过昏迷分隔"）; 
 else 
 {
 string [] entryData = entry.Expression.Split（'，'）; 
 if（entryData.Length！= 2）
 {
抛出新的ArgumentException（" mast provide 2 argument"）; 
} 
 else 
 {
 int lowerLimit，higherLimit; 
 if（Int32.TryParse（entryData [0]，out lowerLimit）&& Int32.TryParse（entryData [1]，out higherLimit））
 {
 CodeTypeReferenceExpression typeRef = new CodeTypeReferenceExpression（ this.GetType（））; 
 CodeExpression [] parameters = new CodeExpression [2]; 
 parameters [0] = new CodePrimitiveExpression（lowerLimit）; 
 parameters [1] = new CodePrimitiveExpression（higherLimit）; 
返回新的CodeMethodInvokeExpression（typeRef，" GetRandomNumber"，参数）; 
} 
 else 
 {
抛出新的ArgumentException（" use valid integers"）; 
} 
} 
} 
} 
} 

< form id =" form1" RUNAT = QUOT;服务器"> 
< div> 
 
< asp：Literal ID =" Literal1" RUNAT = QUOT;服务器" Text ="<％$ RandomNumber：<％= Num1％>，<％= Num2％>％>" /> 
< asp：Button ID =" Button1" RUNAT = QUOT;服务器"文本= QUOT;按钮和QUOT; /> 
 
< br /> 
来自< asp：TextBox ID =" TextBox1" RUNAT = QUOT;服务器"宽度= QUOT; 53px">< / ASP：文本框> 
到< asp：TextBox ID =" TextBox2" RUNAT = QUOT;服务器"宽度= QUOT; 70像素">< / ASP：文本框> 
 
< / div> 
< p> 
& nbsp;< / p> 
< / form> 

解决方案

< blockquote>如果要添加值，它们必须是数字，而不是字符串。您可以使用
int.Parse 或
int.TryParse 从字符串中获取数字。

How can I dynamically add values to a $ expression??

For example I want to take 2 values that a user entered in two different text boxes and add them as values for the RandomNumber (a $Expression that i have created myself) 

<asp:Literal ID="Literal1" runat="server" Text="<%$ RandomNumber: <%= Num1%>, <%= Num2%>%>" />

public string Num1
        {
            get 
            {
                return TextBox1.Text;
            }
        }

        public string Num2
        {
            get
            {
                return TextBox2.Text;
            }
        }

EDIT: I have also tried to set the property as int but still won't make the substitution...

public class RandomNumberExpressionBuilder : System.Web.Compilation.ExpressionBuilder
    {
        public static string GetRandomNumber(int lowerLimit, int higherLimit)
        {
            Random random = new Random();
            int no = random.Next(lowerLimit, higherLimit);
            return no.ToString();
        }
        public override CodeExpression GetCodeExpression(BoundPropertyEntry entry, object parsedData, ExpressionBuilderContext context)
        {
            if (!entry.Expression.Contains(","))
                throw new ArgumentException("must be separated through coma");
            else
            {
                string[] entryData = entry.Expression.Split(',');
                if (entryData.Length != 2)
                {
                    throw new ArgumentException("mast provide 2 argument");
                }
                else
                {
                    int lowerLimit, higherLimit;
                    if (Int32.TryParse(entryData[0], out lowerLimit) && Int32.TryParse(entryData[1], out higherLimit))
                    {
                        CodeTypeReferenceExpression typeRef = new CodeTypeReferenceExpression(this.GetType());
                        CodeExpression[] parameters = new CodeExpression[2];
                        parameters[0] = new CodePrimitiveExpression(lowerLimit);
                        parameters[1] = new CodePrimitiveExpression(higherLimit);
                        return new CodeMethodInvokeExpression(typeRef, "GetRandomNumber", parameters);
                    }
                    else
                    {
                        throw new ArgumentException("use valid integers");
                    }
                }
            }
        }
    }

<form id="form1" runat="server">
    <div>
    
        <asp:Literal ID="Literal1" runat="server" Text="<%$ RandomNumber: <%= Num1%>, <%= Num2%>%>" />
        <asp:Button ID="Button1" runat="server" Text="Button" />
    
        <br />
        from<asp:TextBox ID="TextBox1" runat="server" Width="53px"></asp:TextBox>
        to<asp:TextBox ID="TextBox2" runat="server" Width="70px"></asp:TextBox>
    
    </div>
        <p>
            &nbsp;</p>
    </form>

解决方案

If you want to add values, they must be numeric, not string. You can use int.Parse or int.TryParse to get a number from a string.

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