Write into the CSV

Question

at first I am a novice, I am learning is that only two months. (Sorry for my english, I hope u will understand.) Problem is: I am trying to create a small database with console application. I have student.csv where are all information about students. When I start application, all informations from this .csv will save into Lists. Like this:

 List<Student> zoznam = new List<Student>(); List<string> inicZac = new List<string>(); List<string> ID = new List<string>(); List<string> Meno = new List<string>(); List<string> Priezvisko = new List<string>(); List<string> Adresa = new List<string>(); List<string> DatumNarodenia = new List<string>(); List<string> Heslo = new List<string>(); List<string> Login = new List<string>(); List<string> inicKon = new List<string>(); private int id; StreamReader reader = new StreamReader(File.OpenRead("student.csv")); public databazaStudentov() { while (!reader.EndOfStream) { var line = reader.ReadLine(); var values = line.Split(';'); inicZac.Add(values[0]); ID.Add(values[1]); Meno.Add(values[2]); Priezvisko.Add(values[3]); Adresa.Add(values[4]); DatumNarodenia.Add(values[5]); Heslo.Add(values[6]); Login.Add(values[7]); inicKon.Add(values[8]); zoznam.Add(new Student(values[1], values[2], values[3], values[4], values[5], values[6], values[7])); } }

It works good. But now I want secure an easy write into this .csv when I create a new student in a running application.This function is creating a new student:

 public void addStudent(string meno, string priezvisko, string adresa, string datum) { string tempID = generujID(); //random gener ID string tempLogin = generujLogin(meno, priezvisko); //random gener Login string tempHeslo = generujHeslo(); //random gener password zoznam.Add(new Student(tempID, meno, priezvisko, adresa, datum, tempLogin, tempHeslo)); ID.Add(tempID); Meno.Add(meno); Priezvisko.Add(priezvisko); Adresa.Add(adresa); DatumNarodenia.Add(datum); Login.Add(tempLogin); Heslo.Add(tempHeslo); // I created a new student and now I want save him into the csv }

and here is my .csv: https://i.sstatic.net/iyGCy.jpg

There are probably more ways how to fix it. I will be gratefull if someone show me How to save a new student on a new row or How to overwrite with Lists everything in my student.csv . Thanks for tips and sorry for my english.

just curious why csv as storage format? I'd go with something like JSON that can easily be serialized and deserialized into C# object and has better support for hierarchical data structure just in case. And since you are using file system anyhow, you can just persist and read it as a whole. Flow is something like: load json from storage, deserialize into C# object, make changes in C# object like remove from list or add to list, etc., serialize back to json and write to storage. — Jimmy Chandra
– Jimmy Chandra, Commented Apr 11, 2015 at 14:09

Shyju · Accepted Answer · 2015-04-11 14:30:47Z

I would create a new class to create csv file from your student.

public class CsvGen { private _fileName=string.Empty; private StringBuilder csvRows; public CsvGen(string fileName) { _fileName=fileName; csvRows=new StringBuilder(); } public void Add(Student student) { var row=String.Format("{0},{1},{2},{3}",student.Id,student.Name,student.City, Environment.NewLine); csvRows.Append(row); } public void SaveFile() { System.IO.File.WriteAllText(_fileName,csvRows.ToString()); } }

Now from your other class, you can create a new instance of this class and call the AddStudent method everytime you add an item to the list and call SaveFile after your loop.

CsvGen csvGen=new CsvGen(@"C:\\temp\myFile.csv"); // ^ any location with proper permission for .net to write files. public void AddStudent(int id, string name, string city) { Student stud=new Student(); stud.Id=id; stud.Name=name; stud.City=city; csvGen.Add(stud); }

So once you create all students, You may call the SaveFile method to save the csv file

while (!someCondition) { AddStudent(2,"scott","detroit"); } csvGen.SaveFile();

samuel · Accepted Answer · 2015-04-11 14:39:01Z

A quick solution for your question.

public void addStudent(string meno, string priezvisko, string adresa, string datum) { //your code //......... // I created a new student and now I want save him into the csv using(StreamWriter sw = new StreamWriter("student.csv", true))//true to append after the file { sw.WriteLine("{0};{1};{2};{3};{4};{5};{6};", tempID, meno, priezvisko, adresa, datum, tempLogin, tempHeslo); sw.Close(); } }

christophano · Accepted Answer · 2015-04-11 14:06:59Z

If you want to read and write csv, then I'd recommend you try the CsvHelper library, as it would be much simpler than the way you're doing it currently.

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