Question

客户端应用程序将json数组发送到我的.net应用程序。我正在使用名称值集合接收它。现在我想读取它的值并将其分配给SQL查询的IN子句。

HttpContext context = HttpContext.Current;
NameValueCollection nvc = context.Request.Form;

string co_json = nvc["co_json"];
// jsArray : [{"roll_number":"11","mark":"68"},{"roll_number":"22","mark":"70"}]";

// I want to get the two roll numbers from above json and need to pass it to SQL 
SqlDataAdapter da = new SqlDataAdapter("select * from  student_details where roll_number IN ( ???) ", con);

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

Answer 1

您可以使用Newtonsoft JSON.NET将json转换为自定义c＃对象你可以创建一个这样的类：

public class RollMark 
{
    public string roll_number {get;set;}
    public string mark {get;set;}
}

现在你可以这样做：

HttpContext context = HttpContext.Current;
NameValueCollection nvc = context.Request.Form;
string co_json = nvc["co_json"];// jsArray : [{"roll_number":"11","mark":"68"},{"roll_number":"22","mark":"70"}]";

//collect all rollMarks in json to c# list
var rollMarks = Newtonsoft.Json.JsonConvert.DeserializeObject<List<RollMark>>(co_json );

您现在可以在查询中添加参数，如下所示：

//format your IN query
string[] paramArray = rollMarks.Select(x, i) => "@settings" + i).ToArray();
string query = string.Format("select * from  student_details where roll_number IN ({0})", string.Join(",", paramArray));
SqlDataAdapter da = new SqlDataAdapter(query, con);

DataTable dt = new DataTable();
for (int i = 0; i < rollMarks.Count(); ++i)
{
    da.SelectCommand.Parameters.AddWithValue("@settings", rollMarks[i].roll_number)
}
da.Fill(dt);

Answer 2

首先，拆分你的json数组以找到每个数组项。接下来，创建一个具有项目的每个属性的类。最后将你的每个json项目反序列化到类中。

如何从json数组中读取每个数据并将其分配给SQL Server IN子句

2 个答案: