使用C＃给定条件从XML获取值

Question

I'm kinda new with using XML with C#.

XML CODE:

<LVL2>
  <Tables>
    <TBL_ID>1</TBL_ID>
    <TBL_Name>test1</TBL_Name>
    <MD_ID>1</MD_ID>
  <Tables>
  <Tables>
    <TBL_ID>2</TBL_ID>
    <TBL_Name>test2</TBL_Name>
    <MD_ID>1</MD_ID>
  </Tables>
  <Tables>
    <TBL_ID>3</TBL_ID>
    <TBL_Name>test3</TBL_Name>
    <MD_ID>1</MD_ID>
  </Tables>
</LVL2>

<LVL2>
  <Tables>
    <TBL_ID>1</TBL_ID>
    <TBL_Name>test4</TBL_Name>
    <MD_ID>2</MD_ID>
  </Tables>
  <Tables>
    <TBL_ID>2</TBL_ID>
    <TBL_Name>test5</TBL_Name>
    <MD_ID>2</MD_ID>
  </Tables>
  <Tables>
    <TBL_ID>3</TBL_ID>
    <TBL_Name>test6</TBL_Name>
    <MD_ID>2</MD_ID>
  </Tables>
</LVL2>

How do I insert to a checkedlistbox the text values from tbl_name that has an md_id = 1 only. Here is my current code.

while (xmlReader.Read())
{
    switch (xmlReader.NodeType)
    {

        case XmlNodeType.Element:
            elName = xmlReader.Name;
            break;
        case XmlNodeType.Text:

            if (elName == "TBL_Name" && MD_ID == "1")
            {
                checkedListBox2.Items.Add(xmlReader.Value);
            }

            break;     
    }
}

I can't seem to figure out on how to get the text that has MD_ID = "1" and output:

test4
test5
test6

Answer 1

First of all, the xml is not formatted properly. It should contain a root node and you missed the closing of a <Tables> tag. In the sample example, if you want to choose table names of elements having "MD_ID = 1" , the result will be:

test1
test2
test3

If you want o/p as you mentioned, then the condition will be not equal to 1. Here is the solution:

string xmlInput =  @"
    <root>
    <LVL2>
    <Tables>
     <TBL_ID>1</TBL_ID>
     <TBL_Name>test1</TBL_Name>
     <MD_ID>1</MD_ID>
   </Tables>
   <Tables>
    <TBL_ID>2</TBL_ID>
    <TBL_Name>test2</TBL_Name>
    <MD_ID>1</MD_ID>
   </Tables>
   <Tables>
    <TBL_ID>3</TBL_ID>
    <TBL_Name>test3</TBL_Name>
    <MD_ID>1</MD_ID>
   </Tables>
   </LVL2>
   <LVL2>
   <Tables>
    <TBL_ID>1</TBL_ID>
    <TBL_Name>test4</TBL_Name>
    <MD_ID>2</MD_ID>
   </Tables>
   <Tables>
    <TBL_ID>2</TBL_ID>
    <TBL_Name>test5</TBL_Name>
    <MD_ID>2</MD_ID>
   </Tables>
   <Tables>
    <TBL_ID>3</TBL_ID>
    <TBL_Name>test6</TBL_Name>
    <MD_ID>2</MD_ID>
   </Tables>
  </LVL2>
  </root>";

XDocument  xdoc = XDocument.Parse(xmlInput);

var filteredXML =
  xdoc.Descendants("root")
    .Elements("LVL2")
    .Elements("Tables")
    .Where(x => string.Compare(x.Element("MD_ID").Value, "1") == 0)
    .Select(x => x.Element("TBL_Name").Value)
    .ToList();

Console.WriteLine(filteredXML);

Refer following namespace:

using System.Xml.Linq;