如何使用CsvHelper软件包将C#List写入CSV

我有一个简单的控制台应用程序，它在Program.cs中包含3个用户的列表。在Program.cs中，我想调用

FileOperations.cs

中的一个方法

首先，我的

程序.cs

：

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using CsvHelper;

namespace GimpiesConsoleOOcsvListUI
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create user default instances
            User user0 = new User("Beheer", "beheer@gimpies.nl", "123");
            User user1 = new User("Inkoop", "inkoop@gimpies.nl", "123");
            User user2 = new User("Verkoop", "verkoop@gimpies.nl", "123");

            // List of users (with a list you can add, get and remove items in the list)
            List<User> users = new List<User>();
            users.Add(user0);
            users.Add(user1);
            users.Add(user2);

            // Create login instance
            LoginManager loginMgr = new LoginManager();

            Start:
            // Welcome message
            Console.WriteLine("Welcome to GimpiesTerminal! Choose 1 to login or 2 to register:");

            // Get input from user
            string input = Console.ReadLine();

            bool successfull = false;

            while (!successfull)
            {
                if(input == "1")
                {
                    Console.WriteLine("Enter your username:");
                    string username = Console.ReadLine();
                    Console.WriteLine("Enter your password:");
                    string password = Console.ReadLine();

                    foreach (User user in users)
                    {
                        if (username == user.UserName && password == user.PassWord)
                            {
                                Console.WriteLine("You have successfully logged in !!!");
                                Console.ReadLine();
                                successfull = true;
                            break;  
                            }
                    }
                        if (!successfull)
                            {
                                Console.WriteLine("Your username or password is incorrect, try again !!!");
                            }
                }
                else if (input == "2")
                {
                        // Get user input
                        Console.WriteLine("Enter your username:");
                        string username = Console.ReadLine();

                        Console.WriteLine("Enter your email:");
                        string email = Console.ReadLine();

                        Console.WriteLine("Enter your password:");
                        string password = Console.ReadLine();

                        // Create fresh instance to save input in memory
                        User user = new User(username, email, password);

                        // Adds the user to the excisting list
                        users.Add(user);
                        
                        successfull = true;
                        goto Start;
                }
                else if (input == "3")
                {
                    // Here I want to call the method from FileOperations.cs to write the List here to a CSV file.
                }
                else
                {
                    Console.WriteLine("Try again !!!");
                    break;
                }
            }
            
            // // Loop over stored users within instances inside the list where users are added
            // foreach (User user in users)
            // {
            
            //     if(loginMgr.Login(user))
            //     {
            //         // Login successfull
            //         Console.WriteLine("Login user " + user.UserName);

            //     }
            //     else
            //     {
            //         // Not successfull

            //     }
            // }  
            
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using CsvHelper;

namespace GimpiesConsoleOOcsvListUI
{
    public class FileOperations
    {
        // Handles CRUD within CSV files and able to save them
        public void SaveToCSV(User user)
        {
            using (var mem = new MemoryStream())
            using (var writer = new StreamWriter(mem))
            using (var csvWriter = new CsvWriter(writer))
            {
                csvWriter.Configuration.Delimiter = ";";
                csvWriter.Configuration.HasHeaderRecord = true;
                csvWriter.Configuration.AutoMap<User>();

                csvWriter.WriteHeader<User>();
                csvWriter.WriteRecords(user);

                writer.Flush();
                var result = Encoding.UTF8.GetString(mem.ToArray());
                Console.WriteLine(result);
            }
        }
    } 
}

我在

FileOperations.cs

的第16行遇到以下错误：

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using CsvHelper;

namespace GimpiesConsoleOOcsvListUI
{
    class Program
    {
        static void Main(string[] args)
        {
            // Create user default instances
            User user0 = new User("Beheer", "beheer@gimpies.nl", "123");
            User user1 = new User("Inkoop", "inkoop@gimpies.nl", "123");
            User user2 = new User("Verkoop", "verkoop@gimpies.nl", "123");

            // List of users (with a list you can add, get and remove items in the list)
            List<User> users = new List<User>();
            users.Add(user0);
            users.Add(user1);
            users.Add(user2);

            // Create login instance
            LoginManager loginMgr = new LoginManager();

            Start:
            // Welcome message
            Console.WriteLine("Welcome to GimpiesTerminal! Choose 1 to login or 2 to register:");

            // Get input from user
            string input = Console.ReadLine();

            bool successfull = false;

            while (!successfull)
            {
                if(input == "1")
                {
                    Console.WriteLine("Enter your username:");
                    string username = Console.ReadLine();
                    Console.WriteLine("Enter your password:");
                    string password = Console.ReadLine();

                    foreach (User user in users)
                    {
                        if (username == user.UserName && password == user.PassWord)
                            {
                                Console.WriteLine("You have successfully logged in !!!");
                                Console.ReadLine();
                                successfull = true;
                            break;  
                            }
                    }
                        if (!successfull)
                            {
                                Console.WriteLine("Your username or password is incorrect, try again !!!");
                            }
                }
                else if (input == "2")
                {
                        // Get user input
                        Console.WriteLine("Enter your username:");
                        string username = Console.ReadLine();

                        Console.WriteLine("Enter your email:");
                        string email = Console.ReadLine();

                        Console.WriteLine("Enter your password:");
                        string password = Console.ReadLine();

                        // Create fresh instance to save input in memory
                        User user = new User(username, email, password);

                        // Adds the user to the excisting list
                        users.Add(user);
                        
                        successfull = true;
                        goto Start;
                }
                else if (input == "3")
                {
                    // Here I want to call the method from FileOperations.cs to write the List here to a CSV file.
                }
                else
                {
                    Console.WriteLine("Try again !!!");
                    break;
                }
            }
            
            // // Loop over stored users within instances inside the list where users are added
            // foreach (User user in users)
            // {
            
            //     if(loginMgr.Login(user))
            //     {
            //         // Login successfull
            //         Console.WriteLine("Login user " + user.UserName);

            //     }
            //     else
            //     {
            //         // Not successfull

            //     }
            // }  
            
        }
    }
}

using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using CsvHelper;

namespace GimpiesConsoleOOcsvListUI
{
    public class FileOperations
    {
        // Handles CRUD within CSV files and able to save them
        public void SaveToCSV(User user)
        {
            using (var mem = new MemoryStream())
            using (var writer = new StreamWriter(mem))
            using (var csvWriter = new CsvWriter(writer))
            {
                csvWriter.Configuration.Delimiter = ";";
                csvWriter.Configuration.HasHeaderRecord = true;
                csvWriter.Configuration.AutoMap<User>();

                csvWriter.WriteHeader<User>();
                csvWriter.WriteRecords(user);

                writer.Flush();
                var result = Encoding.UTF8.GetString(mem.ToArray());
                Console.WriteLine(result);
            }
        }
    } 
}

流作者 参数1：无法从

System.IO.StreamWriter

转换为

CsvHelper.ISerializer

第23行：

用户用户 参数1:无法从

GimpiesConsolleoCsvListui.User

转换为

System.Collections.IEnumerable

---

我是C的新手，所以我希望你不要介意这是一个简单的问题

由于在这两种情况下都传递了错误的参数类型，因此会出现错误。

CsvWriter

没有只接受一个参数为

TextWriter

的构造函数。我对这个图书馆不是很熟悉，但我相信它可能在过去就已经做过了。我怀疑您从internet上以前的示例中复制了代码，这些示例已经过时

解决此问题的简单方法是再添加两个参数，因此：

using (var csvWriter = new CsvWriter(writer, CultureInfo.CurrentCulture, false))

第二个错误是因为

CsvWriter.WriteRecords

需要一个

IEnumerable

参数，而不是一个实例。要解决此问题，您需要将您的

列表

传递给它，这样整个代码就变成：

public void SaveToCSV(List<User> users)
{
    using (var mem = new MemoryStream())
    using (var writer = new StreamWriter(mem))
    using (var csvWriter = new CsvWriter(writer, CultureInfo.CurrentCulture, false))
    {
        csvWriter.Configuration.Delimiter = ";";
                
        csvWriter.Configuration.HasHeaderRecord = true;
        csvWriter.Configuration.AutoMap<User>();

        csvWriter.WriteHeader<User>();
        csvWriter.WriteRecords(users);

        writer.Flush();
        var result = Encoding.UTF8.GetString(mem.ToArray());
        Console.WriteLine(result);
    }
}

public void SaveToCSV（列出用户）
{
使用（var mem=new MemoryStream（））
使用（var编写器=新StreamWriter（mem））
使用（var csvWriter=new csvWriter（writer，CultureInfo.CurrentCulture，false））
{
csvWriter.Configuration.Delimiter=“；”；
csvWriter.Configuration.HasHeaderRecord=true；
csvWriter.Configuration.AutoMap（）；
csvWriter.WriteHeader（）；
csvWriter.WriterRecords（用户）；
writer.Flush（）；
var result=Encoding.UTF8.GetString（mem.ToArray（））；
控制台写入线（结果）；
}
}

如果要序列化单个用户对象并显示其序列化的标题和值，可以尝试以下代码：

public void SaveToCSV(User user)
{
    using (var writer = new StringWriter())
    using (var csvWriter = new CsvWriter(writer, CultureInfo.InvariantCulture, leaveOpen: true))
    {
        csvWriter.Configuration.Delimiter = ";";
        csvWriter.Configuration.HasHeaderRecord = true;
        csvWriter.Configuration.AutoMap<User>();

        csvWriter.WriteHeader<User>();
        csvWriter.WriteRecord(user);
        csvWriter.Flush();

        var result = writer.ToString();
        Console.WriteLine(result);
    }
}

---

在第二个示例中，您不需要调用

Flush

，因为

using

block的末尾为您调用了它，并且您对其范围内的CSV内容不感兴趣。

我不了解您的代码流；您有一个要保存的用户列表，您有一个类，该类的方法只将单个用户保存到内存流中（因此不保存到磁盘），然后立即丢弃内存流，这样就不会在任何地方保存任何内容。可能值得仔细阅读您的代码并对算法进行注释，这样您就有了实现目标所需的母语步骤集，然后您就可以评估注释下的c#是否真的符合注释所述；“先用英语（/你的母语）写，然后翻译成c#”不要使用

goto

谢谢你的例子和解释。乔纳森：多亏了你的榜样，我才迈出了几步。还有msmolcic谢谢！你的反馈和例子都让它很有效。现在只剩下一些微调了！：-谢谢你的努力。我也要试一试。我的下一步确实是写入CSV文件。当我尝试了你的所有技巧后，我会回来的。我尝试了写csv文件，它成功了！我现在唯一的问题是列表的第一个条目写在标题项旁边。所以它变成了这样：名字；电子邮件；密码；管理admin@admin.com ; 123销售；sales@admin.com ; 123购买；purchase@admin.com ; 123也许你知道如何解决这个问题？我用一个空的第一个用户做了一个临时解决方案：

//创建用户默认实例user user0=new user（“，”，”）；用户user1=新用户（“Beheer”beheer@gimpies.nl", "123");             用户user2=新用户（“Inkoop”inkoop@gimpies.nl", "123");             用户user3=新用户（“Verkoop”verkoop@gimpies.nl", "123");