我有我的模块中的两个dropdownlists。
在一个下拉列表，我已经硬编码的所有运营商如<,>,<=,>=,==
在第二个下拉列表，我已经硬编码了员工的工资像1000,2000,3000,4000....50000
现在，如果我选择<从一个列表和2000从第二个列表，点击提交按钮，我应该得到谁拥有工资不到2000名员工的名单。
我想这样做在asp.net MVC3
我怎样才能完成这个任务？ 我需要为此编写存储过程？
我创建下拉列表，如：
viewModel.OperatorsList = new[]
{
new SelectListItem { Value = "<", Text = "<" },
new SelectListItem { Value = ">", Text = ">" },
new SelectListItem { Value = "<=", Text = "<=" },
new SelectListItem { Value = ">=", Text = ">=" },
new SelectListItem { Value = "==", Text = "==" }
};
viewModel.SalaryList = new[]
{
new SelectListItem { Value = "1000", Text = "1000" },
new SelectListItem { Value = "2000", Text = "2000" },
new SelectListItem { Value = "3000", Text = "3000" },
// and so on
};
我已经使用它来显示下拉列表中的观点：
<%: Html.DropDownListFor(x => x.Operators, Model.OperatorsList)%>
好了，你可以做这样的事情
假设viewModel是...您的viewModel ，你已经有了一个实体Employee与属性Salary （ int在此示例中，它可能是一个decimal在现实世界）
创建一个静态辅助类
public static class MyHelper
{
// a dictionary for your operators and corresponding ExpressionType
public static Dictionary<string, ExpressionType> ExpressionTypeDictionary = new Dictionary<string, ExpressionType>
{
{"<", ExpressionType.LessThan},
{">", ExpressionType.GreaterThan},
{">=", ExpressionType.GreaterThanOrEqual}
//etc
};
//a method to filter your queryable
public static IQueryable<Employee> FilterSalary(this IQueryable<Employee> queryable, int salary, string operatorType)
{
//left part of the expression : m
var parameter = Expression.Parameter(typeof(Employee), "m");
//body is the right part of the expression : m
Expression body = parameter;
//m.Salary
body = Expression.Property(body, "Salary");
//m.Salary <= 1000 (for example)
body = Expression.MakeBinary(ExpressionTypeDictionary[operatorType], body, Expression.Constant(salary));
//m => m.Salary <=1000
var lambda = Expression.Lambda<Func<Employee, bool>>(body, new[] { parameter });
//so it will be queryable.Where(m => m.Salary <= 1000)
return queryable.Where(lambda);
}
}
用法
var queryable = context.All<Employee>();//or something like that, returning an IQueryable<Employee>
queryable = queryable.FilterSalary(viewModel.Salary, viewModel.Operators);
