LINQ 로 XDocument 클래스 사용해 보기

 

 

http://www.peter-urda.com/2010/08/using-linq-to-extract-information-from-xml-in-csharp

 

 

<?xml version="1.0" encoding="utf-8" ?>

<People>

  <Person>

    <FirstName>Peter</FirstName>

    <LastName>Urda</LastName>

    <Age>21</Age>

    <Gender>M</Gender>

  </Person>

  <Person>

    <FirstName>Joe</FirstName>

    <LastName>White</LastName>

    <Age>30</Age>

    <Gender>M</Gender>

  </Person>

  <Person>

    <FirstName>Katie</FirstName>

    <LastName>Smith</LastName>

    <Age>25</Age>

    <Gender>F</Gender>

  </Person>

</People>

 

xml 이 호출되는 웹서비스 경로를 호출할때는 XDocument.Load() 함수를 통해 가져올 수 있고, xml 문자 글자를 파싱할때는 XDocument.Parse() 함수 사용하면 된다. Descendants 함수를 통해 하위 노드들을 가져올 수 있다.

 

여기서 linq 를 통해 구현이 가능하며 xml 관련 부분은 XDcoument 클래스를 사용해야 한다.

 

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Xml.Linq;

 

namespace UsingXML

{

    // We establish a generic Person Class, and define necessary methods

    class PersonObject

    {

        public string fname { get; set; }

        public string lname { get; set; }

        public int age { get; set; }

        public char gender { get; set; }

 

        public PersonObject()

        {

            this.fname = null;

            this.lname = null;

            this.age = 0;

            this.gender = '0';

        }

        public PersonObject(string f, string l, int a, char g)

        {

            this.fname = f;

            this.lname = l;

            this.age = a;

            this.gender = g;

        }

    }

 

    class ReadAndLoad

    {

        // Declare a public XDocument for use

        public static XDocument XDoc;

 

        static void Main(string[] args)

        {

            // Prompt the user for file path, provide the current local

            // directory if the user wants to use a relative path.

            Console.Write("Current Local Path: ");

            Console.WriteLine(Environment.CurrentDirectory);

            Console.Write("Path to file? > ");

            string UserPath = Console.ReadLine();

  

            // Try to open the XML file

            try

            {

                Console.WriteLine("\nNow Loading: {0}\n", UserPath);

                XDoc = XDocument.Load(@UserPath);

            }

            // Catch "File Not Found" errors

            catch (System.IO.FileNotFoundException)

            {

                Console.WriteLine("No file found!");

                Environment.Exit(1);

            }

            // Catch Argument Exceptions

            catch (System.ArgumentException)

            {

                Console.WriteLine("Invalid path detected!");

                Environment.Exit(1);

            }

            // Catach all other errors, and print them to console.

            catch (Exception err)

            {

                Console.WriteLine("An Exception has been caught:");

                Console.WriteLine(err);

                Environment.Exit(1);

            }

 

            // Define a new List, to store the objects we pull out of the XML

            List<PersonObject> PersonList = new List<PersonObject>();

 

            // Build a LINQ query, and run through the XML building

            // the PersonObjects

            var query = from xml in XDoc.Descendants("Person")

                        select new PersonObject

                        {

                            fname = (string)xml.Element("FirstName"),

                            lname = (string)xml.Element("LastName"),

                            age = (int)xml.Element("Age"),

                            gender = ((string)xml.Element("Gender") == "M" ?

                                'M' :

                                'F')

                        };

            PersonList = query.ToList();

 

            // How many PersonObjects did we find in the XML?

            int ListSize = PersonList.Count;

 

            // Handle statements for 0, 1, or many PersonObjects

            if (ListSize == 0)

            {

                Console.WriteLine("File contains no PersonObjects.\n");

                Environment.Exit(0);

            }

            else if (ListSize == 1)

                Console.WriteLine("Contains 1 PersonObject:\n");

            else

                Console.WriteLine("Contains {0} PersonObjects:\n", ListSize);

 

            // Loop through the list, and print all the PersonObjects to screen

            for (int i = 0; i < ListSize; i++)

            {

                Console.WriteLine(" PersonObject {0}", i);

                Console.WriteLine("------------------------------------------");

                Console.WriteLine(" First Name : {0}", PersonList[i].fname);

                Console.WriteLine(" Last Name  : {0}", PersonList[i].lname);

                Console.WriteLine(" Age ...... : {0}", PersonList[i].age);

                Console.WriteLine(" Gender ... : {0}", PersonList[i].gender);

                Console.Write("\n");

            }

 

            // ...and we are done!

            Environment.Exit(0);

        }

    }

}

 

 

 

약간 추가로 말을 하자면..

 

아래처럼 returnCode, returnMsg 같은 별도로 하나의 값만 가지고 있을 경우엔, SingleOrDefault() 로 하나의 노드를 선택하고 Value 함수를 통해 값을 가져올 수 있다. 해당 노드가 없으면 null 로 반환이 된다.

 

var returnCode = (from e in XDoc.Descendants("returnCode") select e).SingleOrDefault().Value;
var returnMsg = (from e in XDoc.Descendants("returnMsg") select e).SingleOrDefault().Value;