A .NET library for fast and efficient validation and transformation of CSV files.

Structural CSV validation rules adhere to RFC 4180.

Additional content validation rules can be configured by supplying an optional JSON validation profile. A validation profile allows specifying column names, data types, column rules (e.g. if data for that column are required, what the min/max length should be, and so on).

1. Add a reference to FastCsv in your .csproj file:

<Project Sdk="Microsoft.NET.Sdk">

  <ItemGroup>
    <ProjectReference Include="..\..\src\FastCsv\FastCsv.csproj" />
  </ItemGroup>

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net8.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

</Project>

2. Add a using FastCsv; directive at the top of your class file.

3. Create a CsvValidator object and call its Validate method, passing both a stream and a ValidationOptions object into that method.

using FastCsv;

string csvContent = @"NAME,AGE,DOB
John,23,1/1/2012
Mary,34,1/1/1990
Jane,25,1/1/2010
Hana,55,1/1/1970";

CsvValidator validator = new CsvValidator();
var options = new ValidationOptions()
{
    Separator = ',',
    HasHeaderRow = true
};

Stream content = GenerateStreamFromString(csvContent);
ValidationResult result = validator.Validate(content: content, options: options);

Console.WriteLine($"Valid File = {result.IsValid}");

static Stream GenerateStreamFromString(string s)
{
    var stream = new MemoryStream();
    var writer = new StreamWriter(stream);
    writer.Write(s);
    writer.Flush();
    stream.Position = 0;
    return stream;
}

The examples folder contains example code that demonstrates how to use FastCsv.

Let's look at the FastCsv.ConsoleDemo project.

1. Navigate to examples/demo-console/ in a terminal of your choice.
2. Enter the following into the terminal:

dotnet run

3. Observe for the following output:

Valid File = True
 Data Rows         = 4
 Elapsed time (ms) = 3ms
 Columns           = 3
 Error count       = 0
 Warning count     = 0
 Headers = 
  Column 1 = NAME
  Column 2 = AGE
  Column 3 = DOB

That's all there is to it.

This console app includes a hard-coded CSV file in program.cs to make it as simple as possible to run the example. A CSV input file is therefore not required.