Develop Reference

What is the best way to check if a file contains a key before adding a new line?

I have a CSV file containing the following columns -
Key,Value
First,Line
Second,Line
Third,Line
I want to add a new Key-Value to this file given the key is not already present in the file using C#? What would be the best way to do this? Would I have to traverse line by line and check for the Keys or is there any other better way?
I am not using the CSVHelper package or any other CSV writer.

You could do this:
string path = #"PathToFile.csv";
string Content = string.Empty;
using (StreamReader reader = new StreamReader(path))
{
Content = reader.ReadToEnd();
reader.Close();
}
if (!Content.Contains("YourKey"))
{
using (StreamWriter sw = new StreamWriter(path))
{
sw.WriteLine(Content + "\nYourkey,YourValue");
sw.Close();
}
}
Read the file and write all text to a string variable, check the variable if the key exists, if it doesn't then write content back to the file along with your new key. as the file grows it will take longer and longer to search the whole file but it'll work well for a couple thousand lines.

Read CSV file and insert to LocalDB (asp.net MVC)

I'm trying out a project with ASP.Net MVC and have a large CSV file that I want to save to the LocalDB.
I have been following this tutorial (and the ones before that are about MVC): https://learn.microsoft.com/en-us/aspnet/mvc/overview/getting-started/introduction/creating-a-connection-string
Now I want to add data to this database that I have set up and I would like to read this data from a csv file and then save it to my database.
I have tried this: https://www.aspsnippets.com/Articles/Upload-Read-and-Display-CSV-file-Text-File-data-in-ASPNet-MVC.aspx
but when I try to upload my file I get an error that my file is too large?
I would love it if it could be automated so that when I start my application the database will be populated with the data from my csv file (and if it already is populated it will not do it again) or just some way of coding so that I can add the data from my csv file to the database (LocalDB).
protected override void Seed(ProductsDBContext context)
{
Assembly assembly = Assembly.GetExecutingAssembly();
string resourceName = "WebbApplication.App_Data.SeedData.price_detail.csv";
using (Stream stream = assembly.GetManifestResourceStream(resourceName))
{
using (StreamReader reader = new StreamReader(stream, Encoding.UTF8))
{
CsvReader csvReader = new CsvReader(reader);
var products = csvReader.GetRecords<PriceDetail>().ToArray();
context.PriceDetails.AddOrUpdate(c => c.PriceValueId, products);
}
}
}

Your second link includes the following line:
string csvData = System.IO.File.ReadAllText(filePath);
If you are getting an Out of Memory Exception, then you should not load the entire file into memory at once - i.e. do not read all of the text.
The StreamReader has a built-in function to handle this.
System.IO.StreamReader file = new System.IO.StreamReader("WebbApplication.App_Data.SeedData.price_detail.csv");
while((line = file.ReadLine()) != null)
{
System.Console.WriteLine(line);
//Replace with your operation below
}
Potentially the same problem solved at this question.

With Cinchoo ETL - an open source library, you can bulk load CSV file into sqlserver with few lines of code.
using (var p = new ChoCSVReader(** YOUR CSV FILE **)
.WithFirstLineHeader()
)
{
p.Bcp("** ConnectionString **", "** tablename **");
}
For more information, please visit codeproject article.
Hope it helps.

Record count for Excel file with extension CSV

I am trying to count the record of excel file with extension csv with the following code but I am not getting exact number of rows.
int lineCount = 0;
using (var reader = File.OpenText(#fileFullPath))
{
while (reader.ReadLine()!= null)
{
lineCount++;
}
}
Can anyone please advise me on this.

You can do:
var lineCount = File.ReadAllLines(#fileFullPath).Length

First try to open the mentioned .csv file using notepad. If the file opens and readable, It means that your file is human readable and it can be read by File reader line by line without further processing.
If it is so you can use var lineCount = File.ReadAllLines(#fileFullPath).Length. Otherwise you need to have library for reading Excel file

Using FileHelpers to import Excel data using MVC 5

I'm trying to write an application in MVC 5 that will accept a file specified by a user and upload that file information into the database. The file itself has multiple worksheets, which I think FileHelpers handles gracefully, but I can't find any good documentation about working with a byte array. I can get the file just fine, and get to my controller, but don't know where to go from there. I am currently doing this in the controller:
public ActionResult UploadFile(string filepath)
{
//we want to check here that the first file in the request is not null
if (Request.Files[0] != null)
{
var file = Request.Files[0];
byte[] data = new byte[file.ContentLength];
ParseInputFile(data);
//file.InputStream.Read(data, 0, data.Length);
}
ViewBag.Message = "Success!";
return View("Index");
}
private void ParseInputFile(byte[] data)
{
ExcelStorage provider = new ExcelStorage(typeof(OccupationalGroup));
provider.StartRow = 3;
provider.StartColumn = 2;
provider.FileName = "test.xlsx";
}
Am I able to use the Request like that in conjunction with FileHelpers? I just need to read the Excel file into the database. If not, should I be looking into a different way to handle the upload?

So, I decided instead to use ExcelDataReader to do my reading from Excel. It puts the stream (in the below code, test) into a DataSet that I can just manipulate manually. I'm sure it might not be the cleanest way to do it, but it made sense for me, and allows me to work with multiple worksheets fairly easily as well. Here is the snippet of regular code that I ended up using:
//test is a stream here that I get using reflection
IExcelDataReader excelReader = ExcelReaderFactory.CreateOpenXmlReader(test);
DataSet result = excelReader.AsDataSet();
while(excelReader.Read())
{
//process the file
}
excelReader.Close();

How to read from excel in a specific encoding?

I copied from an excel file to a txt file the column names. I read from the txt file the following way:
CultureInfo cultureHU;
Encoding encodingHU;
cultureHU = CultureInfo.GetCultureInfo("hu-HU");
encodingHU = Encoding.GetEncoding(cultureHU.TextInfo.ANSICodePage);
using (StreamReader sr = new StreamReader("settings.txt", encodingHU, true))
{
...
}
How do I read from an Excel file with the same encoding? If I do it the default way (xlRange.Cells[1, i].Value.ToString()), then I get wrong values:
in the excel and txt file I have: "Szerzõdõ"
reading from the text file in encodingHU encoding I get: "Szerződő" (this is the correct format)
reading from excel in C# i get: "Szerzõdõ"

You can convert the bad string to the correct encoding like this:
Console.WriteLine(encodingHU.GetString(Encoding.Default.GetBytes(str)));

I used ExcelDataReader. I needed coding 1250
ExcelReaderConfiguration conf = new ExcelReaderConfiguration();
conf.FallbackEncoding = Encoding.GetEncoding(1250);
using (IExcelDataReader reader = ExcelReaderFactory.CreateReader(stream, conf))
{
...
}