如何从存储过程返回XML？

Question

我创建了一个返回XML的存储过程,我想在我创建的方法中返回该XML.

我有两个问题.首先,在进行一些搜索之后,建议不要使用.ExecuteScalar();它,因为它会截断超过2033个字符的字符串.

所以,我发现了一个名为的函数ExecuteXMlReader(),但是在.NET 4.0(C#)上运行的Visual Web Developer 2010 Express中,它抛出了错误 "System.Data.SqlClient.SqlCommand' does not contain a definition for 'ExecuteXMlReader' and no extension method 'ExecuteXMlReader' accepting a first argument of type 'System.Data.SqlClient.SqlCommand' could be found"

这是我的存储过程:

CREATE PROCEDURE dbo.GETReport
    (@ReportDate date)
AS
SELECT * FROM ReportTbl
WHERE ReportDate = @ReportDate
for xml auto, elements

set nocount on;

RETURN

这是我的方法:

using System.Data;
using System.Data.SqlClient;

...

        //connect        
        SqlConnection conn = new SqlConnection("Data Source=localhost; User Id=foo; Password=foo; Initial Catalog=Database1");
        conn.Open();

        //create command
        SqlCommand cmd = new SqlCommand("dbo.GETReport", conn);
        cmd.Parameters.AddWithValue("@ReportDate", "3/24/2011"); 
        cmd.CommandType = CommandType.StoredProcedure;

        DataReader rd = cmd.ExecuteXMlReader(); //this is where error is occuring
        //also, it is throwing an error for DataReader as well saying there is no
        //type of namespace with that name
        rd.Read();

        string s = rd.ReadOuterXml(); //also dont know if this is how i should return the XML

第二,除了这个ExecuteXMLReader()问题,我不知道返回一个字符串是否是首先返回XML的正确方法...是否有另一个对象类型我应该将其转换为?? 或者我应该使用的另一个功能？

先感谢您!!

Answer 1

首先,SqlCommand有一个ExecuteXmlReader方法,而不是ExecuteXMlReader你写的(这是拼写错误).其次,SqlCommand.ExecuteXmlReader方法返回类型的值XmlReader,而不是DataReader示例中的值.所以将代码更改为:

using (XmlReader reader = cmd.ExecuteXmlReader())
{
    while(reader.Read())
    {
        string s = reader.ReadOuterXml();
        // do something with s
    }
}

应该解决这个问题.

Answer 2

我在@Alex 的简单方法上遇到了麻烦，并且用这种方法好运了：

// Execute a SqlCommand that you've created earlier.
// (Don't forget your 'using' statements around SqlConnection, SqlCommand and XmlReader!)
// This is where our XML will end up 
var xmlDocument = new XmlDocument();

using (XmlReader xmlReader = cmd.ExecuteXmlReader())
{
    // Now xmlReader has the XML but no root element so we can't
    // load it straight into XmlDocument :( But we can use XPathDocument
    // to add a node for us first.
    var xp = new XPathDocument(xmlReader);
    var xn = xp.CreateNavigator();
    XmlNode root = xmlDocument.CreateElement("YourFavouriteRootElementName");
    root.InnerXml = xn.OuterXml;
    xmlDocument.AppendChild(root);
}

// Now xmlDocument has all the XML you have dreamed of

使用reader.Read() ... var s = reader.ReadOuterXml()某种方式错过了我较长的更复杂的XML中的某些元素。我没有去研究为什么，而是转而XPathDocument为我工作。