Reading attribute values with XmlReader

2020-02-10 13:02发布

I have an XML file that I'm trying to read from here, and have the following code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.IO;

namespace XML
{
    class Program
    {
        static void Main(string[] args)
        {
            XmlTextReader textReader = new XmlTextReader("secLendingXML.cfm.xml");
            while (textReader.Read())
            {
                switch (textReader.NodeType)
                {
                    case XmlNodeType.Element:
                        Console.WriteLine(textReader.Name);
                        Console.WriteLine(textReader.Value);
                        break;
                    case XmlNodeType.Text:
                        Console.WriteLine(textReader.Value);
                        break;
                    case XmlNodeType.XmlDeclaration:
                    case XmlNodeType.ProcessingInstruction:
                        Console.WriteLine(textReader.Name + " " + textReader.Value);
                        break;
                    case XmlNodeType.Comment:
                        Console.WriteLine(textReader.Value);
                        break;
                    case XmlNodeType.EndElement:
                        break;
                }
            }
            Console.ReadLine();
        }
    }
}

The code is working properly in the sense that it's reading the nodes and returning the names. But, the issue is that I'm trying to also retrieve the data within the nodes. In other words, when it reads the first section after the test section, it will read:

slnc:DataSet
slnc:Group
slnc:Section
slnc:ActualAvailableToBorrow
*** here ***
slnc:oustandingLoans

This is where I want the textreader to read the following values within the node like confidentiality="F", currency="USD", etc., but it just skips right to the next section without reading these values!

<slnc:actualAvailableToBorrow xmlns:slnc="http://www.newyorkfed.org/xml/schemas/SecLending" 
      confidentiality="F" currency="USD" decimals="0" method="AA" 
      multiplier="5" securityLendingType="AA" status="A" value="1474"/>

How do I get the textreader to read the attribute values? It would be ideal for it to print the value "currency", and then its value: "F", and so on.

标签: c# xml xmlreader
2条回答
淡お忘
2楼-- · 2020-02-10 13:34

Get a Single, Named Attribute

Use XmlTextReader.GetAttribute (MSDN)

case XmlNodeType.Element:
  Console.WriteLine(textReader.Name);
  Console.WriteLine(textReader.Value);
  Console.WriteLine(textReader.GetAttribute("currency"));

One nice feature of this function: it will not cause an Exception if the attribute is not defined - it will simply return Null.

Get All the Attributes

Use XmlTextReader.MoveToAttribute (MSDN)

Use the AttributeCount property in combination with MoveToAttribute:

case XmlNodeType.Element:
  Console.WriteLine(textReader.Name);
  Console.WriteLine(textReader.Value);
  for (int attInd = 0; attInd < textReader.AttributeCount; attInd++){
      textReader.MoveToAttribute( attInd );
      Console.WriteLine(textReader.Name);
      Console.WriteLine(textReader.Value);
  }
  textReader.MoveToElement(); 
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来,给爷笑一个
3楼-- · 2020-02-10 13:50

You could change the loop condition a bit so that it also iterates through attributes:

while (textReader.MoveToNextAttribute() || textReader.Read())
{ 
     switch (textReader.NodeType)
     {
         case XmlNodeType.Element:
             Console.WriteLine(textReader.Name);
             Console.WriteLine(textReader.Value);
             break;
         //...
         case XmlNodeType.Attribute:
             //use textReader.Name and textReader.Value here for attribute name and value
             break;
    }
}

MoveToNextAttribute method advances reader to the next attribute in current element or returns false if it cannot do so.

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