Question

这个想法是每个主题都有多个主题，当我调用函数 getTopicsForSubject() 以便将此数据获取到网站页面时，它仅返回表中的 1 个记录。我正在 JavaScript 文件中使用 console.log(response) 对此进行测试，以查看从存储过程/api 连接传入的内容。我想我需要读取存储过程传递的内容，就好像它是一个数组一样，尽管我不太确定这是如何完成的。

存储过程：

USE [Capstone]
GO
/****** Object:  StoredProcedure [dbo].[getTopicsForSubject]    Script Date: 2/21/2021 11:30:03 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE [dbo].[getTopicsForSubject]
    @SubjectID int
AS
BEGIN
    select  *
    from    Topic
    where   SubjectID = @SubjectID
    return; 
END

API 代码

private static string ExecuteSPGetSubjectsForTopic(string queryString, string subjectID)
{
    string json = "";
    string connectionString = ConfigurationManager.AppSettings["dbconn"].ToString();

    using (SqlConnection conn = new SqlConnection(connectionString))
    {
        conn.Open();

        // 1.  create a command object identifying the stored procedure
        SqlCommand cmd = new SqlCommand(queryString, conn);

        // 2. set the command object so it knows to execute a stored procedure
        cmd.CommandType = CommandType.StoredProcedure;

        // 3. add parameter to command, which will be passed to the stored procedure
        cmd.Parameters.Add(new SqlParameter("@SubjectID", subjectID));

        // execute the command
        using (SqlDataReader rdr = cmd.ExecuteReader())
        {
            // iterate through results, printing each to console
            while (rdr.Read())
            {                    
                json = (string)rdr[0].ToString() + "|" + (string)rdr[1].ToString()+ "|" + (string)rdr[2].ToString() + "|" + (string)rdr[3].ToString();
            }
        }
    }

    return json;
}

JavaScript 代码

function getTopicsForSubject()
{       
    var postObj = {
        subjectID: localStorage.getItem('myFutureCurrentSubject')
    };
    console.log(postObj);

    var req = new XMLHttpRequest();
    req.open('POST', 'https://localhost:44303/api/JSON/getTopicsForSubject', true);
    req.setRequestHeader('Content-Type', 'application/json');
    
    req.onreadystatechange = function() { // Call a function when the state changes.
        if (this.readyState === XMLHttpRequest.DONE && this.status === 200) {               
            console.log(req.response);                      
        }
    }
    
    req.send(JSON.stringify(postObj));
    
    return false;       
}

Answer 1

每次读取一行时，您都在重新初始化 JSON 变量。试试这个：

json += (string)rdr[0].ToString() + "|" + (string)rdr[1].ToString()+ "|" + (string)rdr[2].ToString() + "|" + (string)rdr[3].ToString();

这不是返回数据的正确方式。在 JS 中，你仍然会得到它作为一个字符串，然后像这样解析它以获得实际值：

var array = req.response.split('|');
for (var i = 0; i < array.length; i++) {
    console.log(array[i]);
}

我建议您通过从 API 返回 HTTP 响应而不是字符串来使用正确的方法来处理这些数据。例如。创建一个列表，然后在从阅读器读取时填充它并返回它。试试这个：

 List<object[]> topics = new List<object[]>();
 while (rdr.Read())
 {
    object[] row = new object[rdr.FieldCount];
    for (int i = 0; i < rdr.FieldCount; i++)
    {
        row[i] = rdr[i];
    }
    topics.Add(row);
 }
 return Ok(new { Data = topics });

从存储过程返回多个值

1 个答案: