如何解决从CSV文件读取并“保存”其内容以列出对象并将其加载到Program.cs中
我的小型控制台应用程序的目标是从CSV文件中读取内容并将其内容保存在列表中（有效）。我有一个单独的类与此方法。请参阅UserList.cs中未注释的部分：
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Globalization;
using System.Linq;
using CsvHelper;
namespace GimpiesConsoleOOcsvListUI
{
public class UserList
{
// public static List<User> DefaultUsers()
// {
// // First line to skip a row and position all users correctly under the right headers
// User user0 = new User("","","");
// // Create user default instances
// User user1 = new User("Beheer","beheer@gimpies.nl","123","admin");
// User user2 = new User("Inkoop","inkoop@gimpies.nl","purchase");
// User user3 = new User("Verkoop","verkoop@gimpies.nl","sales");
// // 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);
// users.Add(user3);
// // Return all the users in the List to other classes
// return users;
// }
public void LoadUsersFromCSV(List<User> users)
{
// using (var mem = new MemoryStream())
// using (var writer = new StreamWriter(mem))
using (var reader = new StreamReader("users.csv"))
using (var csvReader = new CsvReader(reader,CultureInfo.InvariantCulture))
{
try
{
csvReader.Configuration.Delimiter = ";";
csvReader.Configuration.IgnoreBlankLines = true;
csvReader.Configuration.HasHeaderRecord = true;
csvReader.Configuration.PrepareHeaderForMatch = (string header,int index) => header.ToLower();
csvReader.Configuration.MissingFieldFound = null;
csvReader.Read();
csvReader.ReadHeader();
// Store all content inside a new List as objetcs
var usersfromcsv = csvReader.GetRecords<User>().ToList();
// return users;
}
catch (CsvHelper.HeaderValidationException exception)
{
Console.WriteLine(exception);
}
}
}
}
}
在我的Program.cs中，我想调用此方法，并使用创建的List的内容来使用登录代码。因此，要检查用户名和密码输入是否正确以及用户是否可以登录。
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Globalization;
using System.Linq;
using CsvHelper;
namespace GimpiesConsoleOOcsvListUI
{
class Program
{
static void Main(string[] args)
{
// List of default users
// List<User> users = UserList.DefaultUsers();
// Working on it... Try to read csv file first and try to read list from method in UserList.cs
// UserList ul = new UserList();
List<User> users = UserList.LoadUsersFromCSV();
// List<User> users =
// ul.LoadUsersFromCSV(users);
// Create login instance
LoginManager loginMgr = new LoginManager();
// Create stock instance
Stock stock = new Stock();
Start:
// Welcome message
Console.WriteLine("Welcome to the Gimpies Console Application! Choose 1 to login or 2 to exit this application:");
// Get input from user
string input = Console.ReadLine();
// Set to false to check if login fails or not
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 && user.userrole == "admin")
{
// Create Admin instance to be able to call methods in that class
Admin am = new Admin();
// Calling the method in Admin.cs to start Menu logic
am.AdminLoggedIn(users);
successfull = true;
break;
}
if (username == user.username && password == user.password && user.userrole == "purchase")
{
// Create Purchase instance to be able to call methods in that class
Purchase pc = new Purchase();
// Calling the method in Purchase.cs to start Menu logic
pc.PurchaseLoggedIn(users);
successfull = true;
break;
}
if (username == user.username && password == user.password && user.userrole == "sales")
{
// Create Sales instance to be able to call methods in that class
Sales sl = new Sales();
// Calling the method in Sales.cs to start Menu logic
sl.SalesLoggedIn(users);
successfull = true;
break;
}
}
if (!successfull)
{
Console.WriteLine("Your username or password is incorrect,try again !!!");
}
}
else if (input == "2")
{
Environment.Exit(-1);
}
else if (input == "3")
{
FileOperations fo = new FileOperations();
// Calling the method from FileOperations.cs to write the List here to a CSV file
fo.WriteUsersToCSV(users);
goto Start;
}
else if (input == "4")
{
FileOperations fo = new FileOperations();
// Calling the method from FileOperations.cs to write the List here to a CSV file
fo.ReadUsersFromCSV(users);
goto Start;
}
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
// }
// }
}
}
}
我收到此错误：
Program.cs(20,41): error CS7036: There is no argument given that corresponds to the required formal parameter 'users' of 'UserList.LoadUsersFromCSV(List<User>)' [/home/pascalmariany/Projects/Csharp/GimpiesConsoleOOcsvList/GimpiesConsoleOOcsvListUI/GimpiesConsoleOOcsvListUI.csproj]
这是我的User.cs及其构造函数：
namespace GimpiesConsoleOOcsvListUI
{
public class User
{
// Constructor
public User(string username,string email,string password,string userrole)
{
_UserName = username;
_Email = email;
_Password = password;
_UserRole = userrole;
}
private string _UserName;
private string _Email;
private string _Password;
private string _UserRole;
public string username
{
get { return _UserName; }
set { _UserName = value; }
}
public string email
{
get { return _Email; }
set { _Email = value; }
}
public string password
{
get { return _Password; }
set { _Password = value; }
}
public string userrole
{
get { return _UserRole; }
set { _UserRole = value; }
}
}
}
要实现我的目标需要做什么？
解决方法
您已将LoadUsersFromCsv方法声明为“获取列表”：
public void LoadUsersFromCSV(List<User> users)
但是您正在尝试像“什么都不做并返回列表”一样使用它
List<User> users = UserList.LoadUsersFromCSV();
编译器在抱怨，因为您没有在“用户”参数中提供列表
看着代码，它读入文件并将其转换为列表，但不返回它，也不填充给出的列表。
我建议您更改LoadUsers方法，使其返回读取的列表，将其从void更改为List<User>并删除users参数
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