关于文件读取和比较的问题

Question

First Off I have a File That Looks Like This:

//Manager Ids

ManagerName: FirstName_LastName
ManagerLoginId: 12345

And a Text Box That has a five digit code(ex. 12345) That gets entered. When the Enter Key Is pressed it is assigned to a String called: "EnteredEmployeeId", Then What I need is to search the Entire file above for "EnteredEmployeeId" and if it matches then it will open another page, if it doesn't find that number then display a message(That tells you no employee Id found).

So essentially Im trying to open a file search the entire document for the Id then return true or false to allow it too either display an error or open a new page, and reset the EnteredEmployeeId to nothing.

My Code So Far:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Rent_a_Car
{
    public partial class Employee_Login_Page : Form
    {
        public Employee_Login_Page()
        {
            InitializeComponent();
        }
        string ManagersPath = @"C:\Users\Name\Visual Studios Project Custom Files\Rent A Car Employee Id's\Managers\Manager_Ids.txt"; //Path To Manager Logins
        string EnteredEmployeeId;


        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void Employee_Id_TextBox_KeyPress(object sender, KeyPressEventArgs e)
        {
            if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&           //Checks Characters entered are Numbers Only and allows them
                (e.KeyChar != '0'))
            {
                e.Handled = true;
            }
            else if (e.KeyChar == (char)13)                                         //Checks if The "Enter" Key is pressed
            {
                EnteredEmployeeId = Employee_Id_TextBox.Text;                         //Assigns EnteredEmployeeId To the Entered Numbes In Text Box          

                bool result = ***IsNumberInFile***(EnteredEmployeeId, "ManagerLoginId:", ManagersPath);
                if (result)
                {
                             //open new window
                }
                else
                {
                    MessageBox.Show("User Not Found");
                }
            }
        }
    }
}

Answer 1

This function will read through whole file and find if there is inserted code. It will work with strings (as it is output of your text box) and will return only true or false (employee is or is not in file) not his name, surname etc.

static bool IsNumberInFile(string numberAsString, string LineName, string FileName)
    {
        var lines = File.ReadAllLines(FileName);

        foreach(var line in lines)
        {
            var trimmedLine = line.Replace(" ", ""); //To remove all spaces in file. Not expecting any spaces in the middle of number
            if (!string.IsNullOrEmpty(trimmedLine) && trimmedLine.Split(':')[0].Equals(LineName) && trimmedLine.Split(':')[1].Equals(numberAsString))
                return true;

        }
        return false;
    } 

//Example of use

    String ManagersPath = @"C:\Users\Name\Visual Studios Project Custom Files\Employee Id's\Managers\Manager_Ids.txt"; //Path To Manager Logins

String EnteredEmployeeId;

private void textBox1_TextChanged(object sender, EventArgs e)
{

}

private void Employee_Id_TextBox_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) &&           //Checks Characters entered are Numbers Only and allows them
        (e.KeyChar != '0'))
            {
                e.Handled = true;
            }
    else if (e.KeyChar == (char)13)                                         //Checks if The "Enter" Key is pressed
    {
        EnteredEmployeeId = Employee_Id_TextBox.Text;                         //Assigns EnteredEmployeeId To the Entered Numbes In Text Box           


        bool result = IsNumberInFile(EnteredEmployeeId, "ManagerLoginId" , ManagersPath) 
        if(result)
           //User is in file
        else
          //User is not in file
    }
}

}

Answer 2

Short answer

Is your question about how to read your file?

private bool ManagerExists(int managerId)
{
    return this.ReadManagers().Where(manager => manager.Id == managerId).Any();
}

private IEnumerable<Manager> ReadManagers()
{
    using (var reader = System.IO.File.OpenText(managersFileName))
    {
        while (!reader.EndOfStream)
        {
            string lineManagerName = reader.ReadLine();
            string lineMangerId = reader.ReadLine();

            string managerName = ExtractValue(lineManagerName);
            int managerId = Int32.Parse(ExtractValue(lineManagerId));

            yield return new Manager
            {
                Id = managerId,
                Name = managerName,
            }
    }
}

private string ExtractValue(string text)
{
    // the value of the read text starts after the space:
    const char separator = ' ';
    int indexSeparator = text.IndexOf(separator);
    return text.SubString(indexSeparator + 1);
}

Long Answer

I see several problems in your design.

The most important thing is that you intertwine your manager handling with your form. You should separate your concerns .

Apparently you have the notion of a sequence of Managers, each Manager has a Name (first name, last name) and a ManagerId, and in future maybe other properties.

This sequence is persistable: it is saved somewhere, and if you load it again, you have the same sequence of Managers.

In this version you want to be able to see if a Manager with a given ManagerId exists. Maybe in future you might want more functionality, like fetching information of a Manager with a certain Id, or Fetch All managers, or let's go crazy: Add / Remove / Change managers!

You see in this description I didn't mention your Forms at all. Because I separated it from your Forms, you can use it in other forms, or even in a class that has nothing to do with a Form, for instance you can use it in a unit test.

I described what I needed in such a general from, that in future I might even change it. Users of my persistable manager collection wouldn't even notice it: I can put it in a JSON file, or XML; I can save the data in a Dictionary, a database, or maybe even fetch it from the inte.net.

All that users need to know, is that they have to create an instance of the class, using some parameters, and bingo, you can fetch Managers.

You also give users the freedom to decide how the data is to be saved: if they want to save it in a JSON file, changes in your form class will be minimal.

An object that stores sequences of objects is quite often called a Repository.

Let's create some classes:

interface IManager
{
    public int Id {get;}
    public string Name {get; set;}
}

interface IManagerRepository
{
    bool ManagerExists(int managerId);

    // possible future extensions: Add / Retrieve / Update / Delete (CRUD)
    IManager Add(IManager manager);
    IManager Find(int managerId);
    void Update(IManager manager);
    void Delete(int ManagerId);
}

class Manager : IManager
{
    public Id {get; set;}
    public string Name {get; set;}
}

class ManagerFileRepository : IManagerRepository,
{
    public ManagerFileRepository(string fileName)
    {
         // TODO implement
    }

    // TODO: implement.
}

The ManagerFileRepository saves the managers in a file. It hides for the outside world how the file is internally structured. It could be your file format, it could be a CSV-file, or JSON / XML.

I also separated an interface, so if you later decide to save the data somewhere else, for instance in a Dictionary (for unit tests), or in a database, users of your Repository class won't see the difference.

Let's first see if you can use this class.

class MyForm : Form
{
    const string managerFileName = ...
    private IManagerRepository ManagerRepository {get;}

    public MyForm()
    {
        InitializeComponent();

        this.ManagerRepository = new ManagerFileRepository(managerFileName);
    }

    public bool ManagerExists(int managerId)
    {
        return this.ManagerRepository.ManagerExists(managerId);
    }

Now let's handle your keyPress:

private void Employee_Id_TextBox_KeyPress(object sender, KeyPressEventArgs e)
{
    TextBox textBox = (TextBox)sender;
    ... // code about numbers and enter key

    int enteredManagerId = Int32.Parse(textBox.Text);
    bool managerExists = this.ManagerExists(enteredManagerId);

    if (managerExists) { ... }

}

This code seems to do what you want in an easy way. It looks transparent. The managerRepository is testable, reusable, simple to extend or change, because users won't notice this. So the class looks good. Let's implement

Implement ManagerFileRepository

There are several ways to implement reading the file:

(1) Read everything at construction time
and keep the read data in memory. If you add Managers they are not saved until you say so. Advantages: after initial startup it is fast. You can make changes and later decide not to save them anyway, so it is just like editing any other file. Disadvantage: if your program crashes, you have lost your changes.

(2) Read the file every time you need information
Advantage: data is always up-to-date, even if others edited the file while your program runs. If you change the manager collection it is immediately saved, so other can use it.

Which solution you choose depends on the size of the file and the importance of never losing data. If you file contains millions of records, then maybe it wasn't very wise to save the data in a file. Consider SQLite to save it in a small fairly fast database.

class ManagerFileRepository : IManagerRepository, IEnumerable<IManager>
{
    private readonly IDictionary<int, IManager> managers;

    public ManagerFileRepository(string FileName)
    {
        this.managers = ReadManagers(fileName);
    }

    public bool ManagerExists(int managerId)
    {
        return this.Managers.HasKey(managerId);
    }

    private static IEnumerable<IManager> ReadManagers(string fileName)
    {
         // See the short answer above
    }
}

Room for improvement

If you will be using your manager repository for more things, consider to let the repository implement ICollection<IManager> and IReadOnlyCollection<IManager> . This is quite simple:

public IEnumerable<IManager> GetEnumerator()
{
    return this.managers.Values.GetEnumerator();
}
public void Add(IManager manager)
{
    this.managers.Add(manager.Id, manager);
}
// etc.

If you add functions to change the manager collection you'll also need a Save method:

public void Save()
{
    using (var writer = File.CreateText(FullFileName))
    {
        const string namePrefix = "ManagerName: ";
        const string idPrefix = "ManagerLoginId: ";
        foreach (var manager in managers.Values)
        {
            string managerLine = namePrefix + manager.Name;
            writer.WriteLine(managerLine);

            string idLine = idPrefix + manager.Id.ToString();
            writer.WriteLine(idLine);
        }
    }
}

Another method of improvement: your file structure . Consider using a more standard file structure: CSV, JSON, XML. There are numerous NUGET packages (CSVHelper, NewtonSoft.Json) that makes reading and writing Managers much more robust.

Summary

Because you separated the concerns of persisting your managers from your form, you can reuse the manager repository, especially if you need functionality to Add / Retrieve / Update / Delete managers.

Because of the separation it is much easier to unit test your functions. And future changes won't hinder users of the repository, because they won't notice that the data has changed.

Answer 3

If your Manager_Ids.txt is in the following format, you can use File.ReadLine() method to traverse the text and query it.

ManagerName: FirstName_LastName1
ManagerLoginId: 12345
ManagerName: FirstName_LastName2
ManagerLoginId: 23456
...

Here is the demo that traverse the.txt.

string ManagersPath = @"D:\Manager_Ids.txt";
string EnteredEmployeeId;

private void textBox_id_KeyDown(object sender, KeyEventArgs e)
{
    int counter = 0;
    bool exist = false;
    string line;
    string str = "";

    if (e.KeyCode == Keys.Enter)
    {
        EnteredEmployeeId = textBox_id.Text;

        System.IO.StreamReader file =
            new System.IO.StreamReader(ManagersPath);
        while ((line = file.ReadLine()) != null)
        {
            str += line + "|";

            if (counter % 2 != 0)
            {
                if (str.Split('|')[1].Split(':')[1].Trim() == EnteredEmployeeId)
                {
                    str = str.Replace("|", "\n");
                    MessageBox.Show(str);
                    exist = true;
                    break;
                }
                str = "";
            }
            counter++;
        }

        if (!exist)
        {
            MessageBox.Show("No such id");
        }

        file.Close();
    }
}

Besides, I recommend to use "xml", "json" or other formats to serialize the data. About storing the data in "xml", you can refer to the following simple demo.

<?xml version="1.0"?>  
<Managers>  
  <Manager>  
    <ManagerName>FirstName_LastName1</ManagerName>  
    <ManagerLoginId>12345</ManagerLoginId>  
  </Manager>  
  <Manager>  
    <ManagerName>FirstName_LastName2</ManagerName>  
    <ManagerLoginId>23456</ManagerLoginId>  
  </Manager>  
</Managers> 

And then use LINQ to XML to query the id.

string ManagersPath = @"D:\Manager_Ids.xml";
string EnteredEmployeeId;

private void textBox_id_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyCode == Keys.Enter)
    {
        EnteredEmployeeId = textBox_id.Text;

        XElement root = XElement.Load(ManagersPath);
        IEnumerable<XElement> manager =
            from el in root.Elements("Manager")
            where (string)el.Element("ManagerLoginId") == EnteredEmployeeId
            select el;
        if(manager.Count() == 0)
        {
            MessageBox.Show("No such id");
        }
        foreach (XElement el in manager)
            MessageBox.Show("ManagerName: " + (string)el.Element("ManagerName") + "\n"
                + "ManagerLoginId: " + (string)el.Element("ManagerLoginId"));
    }
}