Question

我希望SQL数据库表在GridView.Bere中绑定，我使用Ajax来调用名为＆＃39; GetProducts＆＃39;的Web方法。通过＆＃39; url＆＃39;，使用HTTP POST动词。它执行选择查询并返回数据。这是代码，但是显示和错误在'p.ToArray（）＆＃39;。它说无法隐式转换。请帮我使这段代码运行。如果代码的其他部分有任何错误，也建议我：这是.aspx.cs页面中的代码：

namespace AvailableProductsWithAjax
{
    public partial class AvailableProductsWebForm : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                this.BindDummyRow();
            }

          //  GridView1.Columns[0].Visible = false;


        }
        private void BindDummyRow()
        {
            DataTable dummy = new DataTable();
            //dummy.Columns.Add("Product_Id");
            dummy.Columns.Add("Product_Name");
            dummy.Columns.Add("Product_Description");
            dummy.Columns.Add("Product_Category");
            dummy.Columns.Add("Product_Price");
            dummy.Columns.Add("Product_Quantity");
            dummy.Rows.Add();
            GridView1.DataSource = dummy;
            GridView1.DataBind();


        }

        protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }
        [WebMethod]
        public static Products GetProducts()
        {
            List<Products> p = new List<Products>();
            string query = "Select Product_Name, Product_Description, Product_Category, Product_Price, Product_Quantity from Items";


            String cs = ConfigurationManager.ConnectionStrings["WebShopDB"].ConnectionString;
            using (SqlConnection con = new SqlConnection(cs))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter())
                {
                    SqlCommand cmd = new SqlCommand();
                    sda.SelectCommand = cmd;
                    cmd.Connection = con;
                    cmd.CommandText = query;

                    DataTable dt = new DataTable();
                    sda.Fill(dt);

                    foreach (DataRow dtRow in dt.Rows)
                    {
                        Products ps = new Products();

                        ps.Products_Name = dtRow["Product_Name"].ToString();
                        ps.Products_Category = dtRow["Product_Category"].ToString();
                        ps.Products_Description = dtRow["Product_Description"].ToString();
                        ps.Products_Price = dtRow["Product_Price"].ToString();
                        ps.Products_Quantity = dtRow["Product_Quantity"].ToString();


                    }

                }

            }
            return p.ToArray();  
            // Here is the error, cannot be converted implicitly
        }

            public class Products

            public int Products_Id { get; set; }
            public string Products_Name { get; set; }
            public string Products_Description { get; set; }

            public string Products_Category { get; set; }
            public string Products_Price { get; set; }
            public string Products_Quantity { get; set; }
        }
    }
  }

这是JQuery Ajax函数：

<script type="text/javascript" src="http://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.1.1.js"></script>
        <script type="text/javascript">
            $(document).ready(function () {
                $.ajax({
                    type: "POST",
                    url: "AvailableProductsWebForm.aspx/GetProducts",
                    contentType: "application/json; charset=utf-8",
                    data: {},
                    dataType: "json",
                    success: OnSuccess,
                    failure: function (data) {
                        alert(data.d +" Its a failure");
                    },
                    error: function (data) {
                        alert(data.d +" It's an error");
                    }
                });
            });
            function OnSuccess() {
                $("#GridView1").empty();
                if(data.d.length>0)
                {
                    $("#GridView1").append("<tr><th>Product_Name</th> <th>Product_Category</th> <th>Product_Description </th> <th>Product_Price</th> <th> Product_Quantity</th></tr>");
                    for(var i=0; i<data.d.length; i++)
                    {
                        $("#GridView1").append("<tr><td>" + data.d[i].Product_Name +"</td> <td>"
                            + data.d[i].Product_Category + "</td> <td>"
                            + data.d[i].Product_Description +
                            data.d[i].Product_Price + "</td> <td>" +
                            data.d[i].Product_Quantity + "</td> <td>" 
                          );
                    }
                }
            }
        </script>

这是我的数据库查询：

USE [WebShop]
GO
CREATE TABLE [dbo].[Items](
    [Product_Id] [int] IDENTITY(1,1) NOT NULL,
    [Product_Name] [varchar](50) NULL,
    [Product_Description] [varchar](50) NULL,
    [Product_Category] [varchar](50) NULL,
    [Product_Price] [varchar](50) NULL,
    [Product_Quantity] [varchar](50) NULL,
GO

请帮我运行此代码。

Answer 1

您的返回类型为Products，但您尝试返回List<Products> 将方法签名更改为

public static List<Products> GetProducts()

其次，您没有填写返回值。变量p仍为空所以你应该在foreach循环中将ps添加到p

p.Add(ps);

Answer 2

您应该在Products[]而不是Products

中返回

所以你的代码应该是

[WebMethod]
    public static Products[] GetProducts()
    {
        List<Products> p = new List<Products>();
        string query = "Select Product_Name, Product_Description, Product_Category, Product_Price, Product_Quantity from Items";

如果需要更多帮助，请告诉我。

将List复制到新阵列时出错

2 个答案: