创建SqlDataReader的JSON字符串 [英] create JSON string from SqlDataReader

问题描述

我想通了。 <一href=\"http://stackoverflow.com/questions/5554472/create-json-string-from-sqldatareader/5597472#5597472\">Check如下我的答案。

I figured it out. Check out my answer below.

我试图创建一个JSON字符串重新$ P $从数据库表psenting一个行中的HTTP响应返回。这似乎是 Json.NET 将利用一个很好的工具。但是，我不知道该怎么办建立JSON字符串的，而的我是从数据库中读取的

I'm trying to create a JSON string representing a row from a database table to return in an HTTP response. It seems like Json.NET would be a good tool to utilize. However, I'm not sure how to do build the JSON string while I'm reading from the database.

问题是由厌恶的此番言论 / ******** ******** /

The problem is marked by the obnoxious comments /******** ********/

// connect to DB
theSqlConnection.Open(); // open the connection

SqlDataReader reader = sqlCommand.ExecuteReader();
if (reader.HasRows) {

    while(reader.Read()) {

        StringBuilder sb = new StringBuilder();
        StringWriter sw = new StringWriter(sb);

        using (JsonWriter jsonWriter = new JsonTextWriter(sw)) {

            // read columns from the current row and build this JsonWriter
            jsonWriter.WriteStartObject();
            jsonWriter.WritePropertyName("FirstName");

            // I need to read the value from the database
/******** I can't just say reader[i] to get the ith column. How would I loop here to get all columns? ********/
            jsonWriter.WriteValue(... ? ...);
            jsonWriter.WritePropertyName("LastName");
            jsonWriter.WriteValue(... ? ...);
            jsonWriter.WritePropertyName("Email");
            jsonWriter.WriteValue(... ? ...);

            // etc...
            jsonWriter.WriteEndObject();
        }
    }
}

问题是，我不知道如何从该行从 SQLReader的阅读等每一列，我可以打电话 WriteValue ，并给它正确的信息并将其连接到正确的列名。所以，如果行看起来像这样...

The problem is that I don't know how to read each column from the row from the SqlReader such that I can call WriteValue and give it the correct information and attach it to the correct column name. So if a row looks like this...

| FirstName | LastName | Email |

...我将如何创建一个 JsonWriter 每个这样的行，使其包含行的所有列名，并在每列中的相应值，然后使用 JsonWriter 来构建一个JSON字符串，它是准备通过HTTP响应返回？

... how would I create a JsonWriter for each such row such that it contains all column names of the row and the corresponding values in each column and then use that JsonWriter to build a JSON string that is ready for returning through an HTTP Response?

让我知道如果我需要澄清什么。

Let me know if I need to clarify anything.

推荐答案

明白了！下面是C＃...

Got it! Here's the C#...

// ... SQL connection and command set up, only querying 1 row from the table
StringBuilder sb = new StringBuilder();
StringWriter sw = new StringWriter(sb);
JsonWriter jsonWriter = new JsonTextWriter(sw);

try {

    theSqlConnection.Open(); // open the connection

    // read the row from the table
    SqlDataReader reader = sqlCommand.ExecuteReader();
    reader.Read();

    int fieldcount = reader.FieldCount; // count how many columns are in the row
    object[] values = new object[fieldcount]; // storage for column values
    reader.GetValues(values); // extract the values in each column

    jsonWriter.WriteStartObject();
    for (int index = 0; index < fieldcount; index++) { // iterate through all columns

        jsonWriter.WritePropertyName(reader.GetName(index)); // column name
        jsonWriter.WriteValue(values[index]); // value in column

    }
    jsonWriter.WriteEndObject();

    reader.Close();

} catch (SqlException sqlException) { // exception
    context.Response.ContentType = "text/plain";
    context.Response.Write("Connection Exception: ");
    context.Response.Write(sqlException.ToString() + "\n");
} finally {
    theSqlConnection.Close(); // close the connection
}
// END of method
// the above method returns sb and another uses it to return as HTTP Response...
StringBuilder theTicket = getInfo(context, ticketID);
context.Response.ContentType = "application/json";
context.Response.Write(theTicket);

...这样的 StringBuilder的SB 变量是JSON对象重新presents我想查询的行。这里是JavaScript ...

... so the StringBuilder sb variable is the JSON object that represents the row I wanted to query. Here is the JavaScript...

$.ajax({
    type: 'GET',
    url: 'Preview.ashx',
    data: 'ticketID=' + ticketID,
    dataType: "json",
    success: function (data) {

        // data is the JSON object the server spits out
        // do stuff with the data
    }
});

由于<一个href=\"http://stackoverflow.com/questions/5554472/create-json-string-from-sqldatareader/5554885#5554885\">Scott他的回答启发我去我的解决方案。

Thanks to Scott for his answer which inspired me to come to my solution.

斯托伊奇

这篇关于创建SqlDataReader的JSON字符串的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！