Signum Documentation
The documentation comes from the Markdown files in the source code, so is always up-to-date but available only in English. Enjoy!
CSV is a very simple file format for tabular data. Popular applications like Microsoft Excel can easily open and save files in this format.
CSV files really shine as a way to generate tabular logs and integrate data from other sources on your Loading Application, so we decided to make a very lightweight CSV library in Signum.Utilities.
This library has two main functionalities, writing and reading CSV files.
ToCSV method, as other utility methods here, uses public properties and fields to define the columns.
//General overload that takes an stream.
public static void ToCsv<T>(this IEnumerable<T> collection, Stream stream, Encoding encoding = null, CultureInfo culture = null, bool writeHeaders = true, bool autoFlush = false,
Func<CsvColumnInfo<T>, CultureInfo, Func<object, string>> toStringFactory = null)
//Overloads that returns a byte[], using a MemoryStream. Useful for storing in the database or sending to server/client.
public static byte[] ToCsvBytes<T>(this IEnumerable<T> collection, Encoding encoding = null, CultureInfo culture = null, bool writeHeaders = true, bool autoFlush = false,
Func<CsvColumnInfo<T>, CultureInfo, Func<object, string>> toStringFactory = null)
//Overloads that takes a filename, using a FileStream to write the CSV.
//Result: the fileName (to allow chaining)
public static string ToCsvFile<T>(this IEnumerable<T> collection, string fileName, Encoding encoding = null, CultureInfo culture = null, bool writeHeaders = true, bool autoFlush = false, bool append = false,
Func<CsvColumnInfo<T>, CultureInfo, Func<object, string>> toStringFactory = null)Arguments:
- encoding: Used for writing the file. The default one is Windows-1252. You can see what is the current Encoding opening the Csv file in Visual Studio and using Advanced Save Options.
- culture: Used for ToString (DateTime, Numbers...). CultureInfo.CurrentCulture is the default.
- writeHeaders: True to write the property names as column headers.
- toStringFactory: Using this factory of functions, you can return a custom formatter for any specific column.
Using a code very similar to the last example, but using ToCsv with a filename instead:
new DirectoryInfo(@"C:\Users\Public\Pictures\Sample Pictures").GetFiles()
.Select(a=>new
{
a.Name,
Size = a.Length.ToComputerSize(),
a.LastWriteTime,
a.CreationTime
})
.ToCSV("myFile.csv"); Reading CSV files is a bit different. In order to get a IEnumerable<T>
that is filled with your CSV data you need a datasource (the file), and
the type (T in this case) that is used as a template to fill the data.
So the first thing is to define a type that allows us to read the file:
public class CSVFileLine
{
public string Name;
public long Size;
public DateTime LastWriteTime;
public DateTime CreationTime;
}Then we just read the file like this:
var lines = Csv.ReadFile<CSVFileLine>("myFile.csv")Note: Take into account that the order eachf ield/property is declared, not the name, is used to parse each line of the CSV file.
There are many other overloads to use when you don't know the type
//General method that Parses a CSV file from a string IEnumerable
//skipFirstLine: True to avoid reading the first line (headers)
//IMPORTANT: Returns an IEnumerable and uses deferred execution, it's your responsability to keep the Stream open.
public static IEnumerable<T> ReadCVS<T>(this Stream stream, Encoding encoding, CultureInfo culture, bool skipFirst) where T : new()
//Simpler overload taking the fileName
public static List<T> ReadFile<T>(string fileName, Encoding encoding = null, CultureInfo culture = null, int skipLines = 1, bool trim = false,
Func<CsvColumnInfo<T>, CultureInfo, Func<string, object>> parserFactory = null) where T : new()
//Overload taking byte[], useful for reading CSV in entities or received from Client/Server
public static List<T> ReadBytes<T>(byte[] data, Encoding encoding = null, CultureInfo culture = null, int skipLines = 1, bool trim = true,
Func<CsvColumnInfo<T>, CultureInfo, Func<string, object>> parserFactory = null) where T : new()
//General overload taking a Stream
public static IEnumerable<T> ReadStream<T>(Stream stream, Encoding encoding = null, CultureInfo culture = null, int skipLines = 1, bool trim = true,
Func<CsvColumnInfo<T>, CultureInfo, Func<string, object>> parserFactory = null)
//General for parsing just one line
public static T ReadLine<T>(string csvLine, CultureInfo culture = null, bool trim = true, Func<CsvColumnInfo<T>, CultureInfo, Func<string, object>> parserFactory = null)
where T : new()Writing-specific Arguments:
- encoding: Used for reading the file. The default one is Windows-1252. You can see what is the current Encoding opening the Csv file in Visual Studio and using Advanced Save Options.
- culture: Used for Parse (DateTime, Numbers...). CultureInfo.CurrentCulture is the default.
- skipLines: How many initial lines should be skipped, default is 1 (the headers).
- parserFactory: Using this factory of functions, you can return a custom parser for any specific column.
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