Question

如何使用C＃和Asp.net中的Linq从下面的数组中获取学生firstName的所有模块。这可能很容易做但却未能成功。请帮忙。感谢。

ArrayList arrList = new ArrayList();  //new array list for students
        arrList.Add(
            new Student
            {
                FirstName = "Svetlana",
                LastName = "Omelchenko",
                Password = "hh",
                modules = new string[] { "001", "002", "003", "004" }
            });
        arrList.Add(
            new Student
            {
                FirstName = "Claire",
                LastName = "O’Donnell",
                modules = new string[] { "001", "002", "003", "004" }
            });
        arrList.Add(
            new Student
            {
                FirstName = "Sven",
                LastName = "Mortensen",
                modules = new string[] { "001", "002", "003", "004" }
            });
        arrList.Add(
            new Student
            {
                FirstName = "Cesar",
                LastName = "Garcia",
                modules = new string[] { "HH", "KK", "LL", "OO" }
            });





            var query = from Student student in arrList
                    where student.FirstName == "Cesar"
                    select  query;

           GridView1.DataSource = query;


           GridView1.DataBind();

我想将结果放在Asp.net的网格表中。请帮忙!!

Answer 1

您在查询结束时缺少ToList。

yourGridView.DataSource = (from Student s in arrList
                    where s.FirstName == "Cesar"
                    select s).ToList();

然后将其绑定到gridview。

Answer 2

您应该避免使用ArrayLists。改为使用List。

List<Student> StudentList = new List<Student>(); /* ... */

您的查询应该如下：

var query = from student in StudentList
            where student.FirstName == "Cesar"
            select  student;

然后绑定你的网格：

 GridView1.DataSource = query.ToList();
 GridView1.DataBind();

Answer 3

请考虑使用List<Student>：

List<Student> list = new List<Student>();  
    list.Add(
       // ... Just like in your OP
     });

然后得到结果：

var result = from student in list
             where student.FirstName == "Cesar"
             select  student;

然后，您应该可以使用返回的ToList()上的IEnumerable将结果添加到数据源：

 gridView.DataSource = result.ToList();

使用LINQ获取数据并在gridview中显示结果

3 个答案: