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using System;
using System.Web.UI;
using System.Web.Compilation;
using System.CodeDom;
using System.ComponentModel;
public class RandomNumberExpressionBuilder : ExpressionBuilder
{
public static string GetRandomNumber(int lowerLimit, int upperLimit)
{
Random rand = new Random();
int randValue = rand.Next(lowerLimit, upperLimit + 1);
return randValue.ToString();
}
public override CodeExpression GetCodeExpression(BoundPropertyEntry entry, object parsedData,ExpressionBuilderContext context){
if (!entry.Expression.Contains(","))
{
throw new ArgumentException("Must include two numbers separated by a comma.");
}
else
{
string[] numbers = entry.Expression.Split(',');
if (numbers.Length != 2)
{
throw new ArgumentException("Only include two numbers.");
}
else
{
int lowerLimit, upperLimit;
if (Int32.TryParse(numbers[0], out lowerLimit) && Int32.TryParse(numbers[1], out upperLimit)){
Type type = entry.DeclaringType;
PropertyDescriptor descriptor = TypeDescriptor.GetProperties(type)[entry.PropertyInfo.Name];
CodeExpression[] expressionArray = new CodeExpression[2];
expressionArray[0] = new CodePrimitiveExpression(lowerLimit);
expressionArray[1] = new CodePrimitiveExpression(upperLimit);
return new CodeCastExpression(descriptor.PropertyType, new CodeMethodInvokeExpression(new CodeTypeReferenceExpression(base.GetType()), "GetRandomNumber", expressionArray));
}
else
{
throw new ArgumentException("Use valid integers.");
}
}
}
}
}
File: Web.config
<?xml version="1.0"?>
<configuration xmlns="http://schemas.microsoft.com/.NetConfiguration/v2.0">
<appSettings/>
<connectionStrings>
<add name="Northwind" connectionString="Data Source=localhost;Initial Catalog=Northwind;Integrated Security=SSPI"/>
</connectionStrings>
<system.web>
<compilation debug="true">
<expressionBuilders>
<add expressionPrefix="RandomNumber" type="RandomNumberExpressionBuilder"/>
</expressionBuilders>
</compilation>
<authentication mode="Windows"/>
</system.web>
</configuration>
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