I want to import some data from a csv file, but I've encountered a small problem I can't really figure out.
The person who gave me this file, added comma seperated values in cells, so when I split them they will be added to the list. Instead, I would like to get all values per column as a string, I just can't really figure out how.
For example, the column I'm talking about, is about the days a restaurant is open. This can be Mo, Tu, We, Su, but it can also be Mo, Tu.
Is there a way I can just loop over de values per column, instead of by the comma seperated values?
I'm currently using it like this, but this just adds each day to the total list of values:
using (var fs = File.OpenRead(csvUrl))
using (var reader = new StreamReader(fs, Encoding.UTF8))
{
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
if (i > 0)
{
var values = line.Split(',');
}
}
}
Use TextFieldParser to parse CSV files:
TextFieldParser parser = new TextFieldParser(new StringReader(lineContent));
parser.SetDelimiters(",");
string[] rawFields = parser.ReadFields();
lineContent is a string with the content of the current line in your file.
TextFieldParser is available in the namespace:
Microsoft.VisualBasic.FileIO
Don't mind abaout the Visual Basic part it works fine in C#
EDIT
In your code you could implement it like this:
using (var fs = File.OpenRead(csvUrl))
using (var reader = new StreamReader(fs, Encoding.UTF8))
{
while (!reader.EndOfStream)
{
var line = reader.ReadLine();
if (i > 0)
{
TextFieldParser parser = new TextFieldParser(new StringReader(lineContent));
parser.SetDelimiters(",");
string[] rawFields = parser.ReadFields();
}
}
}
Best solution so far to deal with CSV values is using the .NET built in libraries:
Its explained here in my StackOverflow answer here:
Reading CSV file and storing values into an array
For easy reference, I am including the code here as well.
using Microsoft.VisualBasic.FileIO;
var path = #"C:\Person.csv"; // Habeeb, "Dubai Media City, Dubai"
using (TextFieldParser csvParser = new TextFieldParser(path))
{
csvParser.CommentTokens = new string[] { "#" };
csvParser.SetDelimiters(new string[] { "," });
csvParser.HasFieldsEnclosedInQuotes = true;
// Skip the row with the column names
csvParser.ReadLine();
while (!csvParser.EndOfData)
{
// Read current line fields, pointer moves to the next line.
string[] fields = csvParser.ReadFields();
string Name = fields[0];
string Address = fields[1];
}
}
More details about the parser is given here: http://codeskaters.blogspot.ae/2015/11/c-easiest-csv-parser-built-in-net.html
I have several anchor/link tags on my page that all of them has runat="server" and a specific ID on it, is there a way to get them to an Array and then loop through them?
There may be a better way, but here's how I would do this:
Let's say tags in your page look like this:
<a id="id12345">Some Content </a>
Load the HTML file into memory with FileStream, the read the file line by line looking for tags with the id property. When found, perform some string split operations and replacements.
I would use a List, but can use an array if you want.
List<string> ids = new List<string>();
string line;
using (FileStream fs = new FileStream(#"\\path\\to\\file", FileMode.Open))
using (StreamReader reader = new StreamReader(fs))
{
while ((line = reader.ReadLine()) != null)
{
if (line.Contains("<div id="))
{
string[] split1 = line.Split('=');
string[] split2 = split1[1].Split('>');
//remove quotes
ids.Add(split2[0].Replace('"', ' '));
}
}
}
//now look through the list
foreach(string s in ids)
{
//do stuff
}
I am using the CSVHelper library, which can extract a list of objects from a CSV file with just three lines of code:
var streamReader = // Create a reader to your CSV file.
var csvReader = new CsvReader( streamReader );
List<MyCustomType> myData = csvReader.GetRecords<MyCustomType>();
However, by file has nonsense lines and I need to skip the first ten lines in the file. I thought it would be nice to use LINQ to ensure 'clean' data, and then pass that data to CsvFReader, like so:
public TextReader GetTextReader(IEnumerable<string> lines)
{
// Some magic here. Don't want to return null;
return TextReader.Null;
}
public IEnumerable<T> ExtractObjectList<T>(string filePath) where T : class
{
var csvLines = File.ReadLines(filePath)
.Skip(10)
.Where(l => !l.StartsWith(",,,"));
var textReader = GetTextReader(csvLines);
var csvReader = new CsvReader(textReader);
csvReader.Configuration.ClassMapping<EventMap, Event>();
return csvReader.GetRecords<T>();
}
But I'm really stuck into pushing a 'static' collection of strings through a stream like a TextReaer.
My alternative here is to process the CSV file line by line through CsvReader and examine each line before extracting an object, but I find that somewhat clumsy.
The StringReader Class provides a TextReader that wraps a String. You could simply join the lines and wrap them in a StringReader:
public TextReader GetTextReader(IEnumerable<string> lines)
{
return new StringReader(string.Join("\r\n", lines));
}
An easier way would be to use CsvHelper to skip the lines.
// Skip rows.
csvReader.Configuration.IgnoreBlankLines = false;
csvReader.Configuration.IgnoreQuotes = true;
for (var i = 0; i < 10; i++)
{
csvReader.Read();
}
csvReader.Configuration.IgnoreBlankLines = false;
csvReader.Configuration.IgnoreQuotes = false;
// Carry on as normal.
var myData = csvReader.GetRecords<MyCustomType>;
IgnoreBlankLines is turned off in case any of those first 10 rows are blank. IgnoreQuotes is turned off so you don't get any BadDataExceptions if those rows contain a ". You can turn them back on after for normal functionality again.
If you don't know the amount of rows and need to test based on row data, you can just test csvReader.Context.Record and see if you need to stop. In this case, you would probably need to manually call csvReader.ReadHeader() before calling csvReader.GetRecords<MyCustomType>().
I have logs stored in a txt file in the following format.
======8/4/2010 10:20:45 AM=========================================
Processing Donation
======8/4/2010 10:21:42A M=========================================
Sending information to server
======8/4/2010 10:21:43 AM=========================================
I need to parse these lines into a list where the information betweeen "====" lines is counted as one record to display on web page using paging in ASP.NET MVC.
Example: The first record entry would be
======8/4/2010 10:20:45 AM=================================================
Processing Donation
I had no luck so far. How can I do it?
Whilst reading in the file could you do a check to see if the line ends with =====
var sBuilder = new StringBuilder()
bool lineEnd = false;
var items = new List<string>();
string currentLine = String.Empty
using(var file = new StringReader("log.txt"))
{
while( (currentLine = file.ReadLine()) != null)
{
if(currentLine.EndsWith("===="))
{
items.Add(sBuilder.ToString());
sBuilder.Clear();
}
else
sBuilder.Append(currentLine);
}
}
It's a bit verbose but might give you some ideas
So... Ignore the verbose code in my other answer. Instead use this two line wonder:
string texty = "=====........"; //File data
var matches = Regex.Matches(texty, #"={6}(?<Date>.+)={41}\s*(?<Message>.+)");
var results = matches.Cast<Match>().Select(m => new {Date = m.Groups["Date"], Message = m.Groups["Message"]});
I always forget about regular expressions.
How do I read a CSV file using C#?
A choice, without using third-party components, is to use the class Microsoft.VisualBasic.FileIO.TextFieldParser (http://msdn.microsoft.com/en-us/library/microsoft.visualbasic.fileio.textfieldparser.aspx) . It provides all the functions for parsing CSV. It is sufficient to import the Microsoft.VisualBasic assembly.
var parser = new Microsoft.VisualBasic.FileIO.TextFieldParser(file);
parser.TextFieldType = Microsoft.VisualBasic.FileIO.FieldType.Delimited;
parser.SetDelimiters(new string[] { ";" });
while (!parser.EndOfData)
{
string[] row = parser.ReadFields();
/* do something */
}
You can use the Microsoft.VisualBasic.FileIO.TextFieldParser class in C#:
using System;
using System.Data;
using Microsoft.VisualBasic.FileIO;
static void Main()
{
string csv_file_path = #"C:\Users\Administrator\Desktop\test.csv";
DataTable csvData = GetDataTableFromCSVFile(csv_file_path);
Console.WriteLine("Rows count:" + csvData.Rows.Count);
Console.ReadLine();
}
private static DataTable GetDataTableFromCSVFile(string csv_file_path)
{
DataTable csvData = new DataTable();
try
{
using(TextFieldParser csvReader = new TextFieldParser(csv_file_path))
{
csvReader.SetDelimiters(new string[] { "," });
csvReader.HasFieldsEnclosedInQuotes = true;
string[] colFields = csvReader.ReadFields();
foreach (string column in colFields)
{
DataColumn datacolumn = new DataColumn(column);
datacolumn.AllowDBNull = true;
csvData.Columns.Add(datacolumn);
}
while (!csvReader.EndOfData)
{
string[] fieldData = csvReader.ReadFields();
//Making empty value as null
for (int i = 0; i < fieldData.Length; i++)
{
if (fieldData[i] == "")
{
fieldData[i] = null;
}
}
csvData.Rows.Add(fieldData);
}
}
}
catch (Exception ex)
{
}
return csvData;
}
You could try CsvHelper, which is a project I work on. Its goal is to make reading and writing CSV files as easy as possible, while being very fast.
Here are a few ways you can read from a CSV file.
// By type
var records = csv.GetRecords<MyClass>();
var records = csv.GetRecords( typeof( MyClass ) );
// Dynamic
var records = csv.GetRecords<dynamic>();
// Using anonymous type for the class definition
var anonymousTypeDefinition =
{
Id = default( int ),
Name = string.Empty,
MyClass = new MyClass()
};
var records = csv.GetRecords( anonymousTypeDefinition );
I usually use a simplistic approach like this one:
var path = Server.MapPath("~/App_Data/Data.csv");
var csvRows = System.IO.File.ReadAllLines(path, Encoding.Default).ToList();
foreach (var row in csvRows.Skip(1))
{
var columns = row.Split(';');
var field1 = columns[0];
var field2 = columns[1];
var field3 = columns[2];
}
I just used this library in my application. http://www.codeproject.com/KB/database/CsvReader.aspx. Everything went smoothly using this library, so I'm recommending it. It is free under the MIT License, so just include the notice with your source files.
I didn't display the CSV in a browser, but the author has some samples for Repeaters or DataGrids. I did run one of his test projects to test a Sort operation I have added and it looked pretty good.
You can try Cinchoo ETL - an open source lib for reading and writing CSV files.
Couple of ways you can read CSV files
Id, Name
1, Tom
2, Mark
This is how you can use this library to read it
using (var reader = new ChoCSVReader("emp.csv").WithFirstLineHeader())
{
foreach (dynamic item in reader)
{
Console.WriteLine(item.Id);
Console.WriteLine(item.Name);
}
}
If you have POCO object defined to match up with CSV file like below
public class Employee
{
public int Id { get; set; }
public string Name { get; set; }
}
You can parse the same file using this POCO class as below
using (var reader = new ChoCSVReader<Employee>("emp.csv").WithFirstLineHeader())
{
foreach (var item in reader)
{
Console.WriteLine(item.Id);
Console.WriteLine(item.Name);
}
}
Please check out articles at CodeProject on how to use it.
Disclaimer: I'm the author of this library
I recommend Angara.Table, about save/load: http://predictionmachines.github.io/Angara.Table/saveload.html.
It makes column types inference, can save CSV files and is much faster than TextFieldParser. It follows RFC4180 for CSV format and supports multiline strings, NaNs, and escaped strings containing the delimiter character.
The library is under MIT license. Source code is https://github.com/Microsoft/Angara.Table.
Though its API is focused on F#, it can be used in any .NET language but not so succinct as in F#.
Example:
using Angara.Data;
using System.Collections.Immutable;
...
var table = Table.Load("data.csv");
// Print schema:
foreach(Column c in table)
{
string colType;
if (c.Rows.IsRealColumn) colType = "double";
else if (c.Rows.IsStringColumn) colType = "string";
else if (c.Rows.IsDateColumn) colType = "date";
else if (c.Rows.IsIntColumn) colType = "int";
else colType = "bool";
Console.WriteLine("{0} of type {1}", c.Name, colType);
}
// Get column data:
ImmutableArray<double> a = table["a"].Rows.AsReal;
ImmutableArray<string> b = table["b"].Rows.AsString;
Table.Save(table, "data2.csv");
You might be interested in Linq2Csv library at CodeProject. One thing you would need to check is that if it's reading the data when it needs only, so you won't need a lot of memory when working with bigger files.
As for displaying the data on the browser, you could do many things to accomplish it, if you would be more specific on what are your requirements, answer could be more specific, but things you could do:
1. Use HttpListener class to write simple web server (you can find many samples on net to host mini-http server).
2. Use Asp.Net or Asp.Net Mvc, create a page, host it using IIS.
Seems like there are quite a few projects on CodeProject or CodePlex for CSV Parsing.
Here is another CSV Parser on CodePlex
http://commonlibrarynet.codeplex.com/
This library has components for CSV parsing, INI file parsing, Command-Line parsing as well. It's working well for me so far. Only thing is it doesn't have a CSV Writer.
This is just for parsing the CSV. For displaying it in a web page, it is simply a matter of taking the list and rendering it however you want.
Note: This code example does not handle the situation where the input string line contains newlines.
public List<string> SplitCSV(string line)
{
if (string.IsNullOrEmpty(line))
throw new ArgumentException();
List<string> result = new List<string>();
int index = 0;
int start = 0;
bool inQuote = false;
StringBuilder val = new StringBuilder();
// parse line
foreach (char c in line)
{
switch (c)
{
case '"':
inQuote = !inQuote;
break;
case ',':
if (!inQuote)
{
result.Add(line.Substring(start, index - start)
.Replace("\"",""));
start = index + 1;
}
break;
}
index++;
}
if (start < index)
{
result.Add(line.Substring(start, index - start).Replace("\"",""));
}
return result;
}
}
I have been maintaining an open source project called FlatFiles for several years now. It's available for .NET Core and .NET 4.5.1.
Unlike most of the alternatives, it allows you to define a schema (similar to the way EF code-first works) with an extreme level of precision, so you aren't fight conversion issues all the time. You can map directly to your data classes, and there is also support for interfacing with older ADO.NET classes.
Performance-wise, it's been tuned to be one of the fastest parsers for .NET, with a plethora of options for quirky format differences. There's also support for fixed-length files, if you need it.
you can use this library: Sky.Data.Csv
https://www.nuget.org/packages/Sky.Data.Csv/
this is a really fast CSV reader library and it's really easy to use:
using Sky.Data.Csv;
var readerSettings = new CsvReaderSettings{Encoding = Encoding.UTF8};
using(var reader = CsvReader.Create("path-to-file", readerSettings)){
foreach(var row in reader){
//do something with the data
}
}
it also supports reading typed objects with CsvReader<T> class which has a same interface.