Helpwiz.FastCsvReader 1.0.1

Helpwiz.FastCsvReader

A fast compiled expression based csv reader.

Capabilities

Allows custom delimiter characters. Allows quoted values with commas inside e.g. "My value, my second value and my third value"

Limitations

Does not allow multi-line values Does not allow values containing quotes (i.e. no escaped quotes). Requires a header row for the csv file.

Performance

Because the property access expressions are compiled, the library will load csv files at the maximum speed possible.

Getting started

Basic Usage

If you want the csv data to populate a class, make settable properties of all the header fields in the class, and the reader will read into that class

private string[] testData = new []
{ 
  "A, B, C, D", 
  "1,Two,3.0,"
};

private class TargetType 
{
  public int A { get; set; }
  
  public string B { get; set; }
  
  public double C { get; set; }
  
  public int? D { get; set; }
}

//...

public IEnumerable<TargetType> ReadElements() => FastCsvReader.ReadAs<TargetType>(testData);

Named properties

If you want the properties of the target type to differ in name from the header fields, you can use a [CsvProperty] attribute. Note header names are trimmed when matching to properties.

private string[] testData = new[]
{
  "A property, B property, C property, D property",
  "1,Two,3.0,"
};

private class TargetType 
{
  [CsvProperty("A property")]
  public int A { get; set; }
  
  [CsvProperty("B property")]
  public string B { get; set; }
  
  [CsvProperty("C property")]
  public double C { get; set; }
  
  [CsvProperty("D property")]
  public int? D { get; set; }
}

Data conversion and Custom Delimiters

Sensible defaults for string, int, double, DateTime, int?, double? and DateTime? are provided by default. You can override the default behaviour of this and extend to other datatypes as follows:

  var converter = new DefaultConverterSpec();
  converter.SetConverter<int?>(s =>
  {
    if (string.IsNullOrWhiteSpace(s)) return null;
    if (!int.TryParse(s, out int value)) return null;
    return value;
  });
  
  //Read the file with ¬ as the delimiter character and with custom handling for nullable integers.
  var result = FastCsvReader.ReadAs<DefaultData2>(testData3, '¬', converter).ToArray();

Helpwiz

Helpwiz is an online marketplace for independent domestic cleaners. We allow clients to find a cleaner and book a clean in a simple, one-pass process. We have cleaners in many locations throughout the UK.

We provide this code for free, without any license contraints, but we do hope that, if you make use of the code, you will link back to us or otherwise give us a shout out.