如何使用 Foreach 遍历集合以构建 XDocument？

Posted 2023-02-22

【中文标题】如何使用 Foreach 遍历集合以构建 XDocument？

【英文标题】：How can I iterate through a collection with Foreach to build an XDocument?

【发布时间】：2011-03-18 08:10:34

【问题描述】：

以下代码给了我错误：

最好的重载方法匹配 'System.Xml.Linq.XElement.XElement(System.Xml.Linq.XName, object)' 有一些无效的参数。

我必须进行哪些更改才能使用 Foreach 构建 XDocument 来遍历我的 List<Customer> 集合？

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

namespace test_xml3

    class Program
    
        static void Main(string[] args)
        

            List<Customer> customers = new List<Customer> 
                new Customer FirstName="Jim", LastName="Smith", Age=27,
                new Customer FirstName="Hank", LastName="Moore", Age=28,
                new Customer FirstName="Jay", LastName="Smythe", Age=44
            ;

            Console.WriteLine(BuildXmlWithLINQ(customers));
            Console.ReadLine();
        

        private static string BuildXmlWithLINQ(List<Customer> customers)
        
            XDocument xdoc = new XDocument
            (
                new XDeclaration("1.0", "utf-8", "yes"),
                new XElement("customers",
                    customers.ForEach(c => new XElement("customer", 
                        new XElement("firstName", c.FirstName),
                        new XElement("lastName", c.LastName)
                    )
                )
            );
            return xdoc.Declaration.ToString() + Environment.NewLine + xdoc.ToString();
        

    

    public class Customer
    
        public string FirstName  get; set; 
        public string LastName  get; set; 
        public int Age  get; set; 
    

添加：

感谢您的所有回答，我也想出了这个可行的方法：

private static string BuildXmlWithLINQ2(List<Customer> customers)

    XDocument xdoc = new XDocument(
        new XDeclaration("1.0", "utf-8", "yes")
    );
    XElement xRoot = new XElement("customers");
    xdoc.Add(xRoot);

    foreach (var customer in customers)
    
        XElement xElement = new XElement("customer",
            new XElement("firstName", customer.FirstName),
            new XElement("lastName", customer.LastName),
            new XElement("age", customer.Age)
        );
        xRoot.Add(xElement);
    
    return xdoc.Declaration.ToString() + Environment.NewLine + xdoc.ToString();

【问题讨论】：

你在代码中缺少一个括号，在... c=> new XElement(...附近

【参考方案1】：

您必须将customers.ForEach 更改为customers.ConvertAll。

【参考方案2】：

ForEach 返回 void，而不是对新创建的集合的引用。

以下作品

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

namespace test_xml3

    class Program
    
        static void Main(string[] args)
        

            List customers = new List 
                new Customer FirstName="Jim", LastName="Smith", Age=27,
                new Customer FirstName="Hank", LastName="Moore", Age=28,
                new Customer FirstName="Jay", LastName="Smythe", Age=44
            ;

            Console.WriteLine(BuildXmlWithLINQ(customers));
            Console.ReadLine();
        

        private static string BuildXmlWithLINQ(List customers)
        
            XDocument xdoc = new XDocument
            (
                new XDeclaration("1.0", "utf-8", "yes"),
                new XElement("customers",
                    from c in customers select
                        new XElement("customer", 
                            new XElement("firstName", c.FirstName),
                            new XElement("lastName", c.LastName)
                        )
                )

            );
            return xdoc.Declaration.ToString() + Environment.NewLine + xdoc.ToString();
        

    

    public class Customer
    
        public string FirstName  get; set; 
        public string LastName  get; set; 
        public int Age  get; set;