Csv2Json Library

The Csv2Json library provides methods to convert CSV (Comma-Separated Values) content into JSON format in C#. This utility class can handle various options and scenarios while parsing the input data. The following sections describe its usage, features, and code structure.

Dependencies

To use this library, make sure you have installed or referenced the System.Text and System.Text.Json namespaces from .NET 5.0+ in your project.

Options Class

The Options class is a custom class that allows users to specify their preferences for CSV-to-JSON conversion:

1. ContainsHeader (bool): Indicates whether the first line of the input content contains column headers (default value: true).
2. UseAvailableHeader (bool): Specifies if available header values should be used as field names in JSON when present and ContainsHeader == true. If this is set to false, it will use a predefined prefix instead. Default value is true.
3. FieldPrefixIfNoHeader (default: "item"): A string that acts as the default field name prefix if there's no header line available or headers are not used (UseAvailableHeader == false). The resulting JSON structure will have keys like "item0", "item1", etc.
4. SplitChar (default: ','): The character to split CSV columns on while reading the input content. Default value is a comma.

Methods

The library offers two main methods for converting CSV to JSON:

ToJsonAsync(Stream content, Options options)

This asynchronous method accepts a stream of the CSV data and an Options instance as parameters. It reads the input stream line by line using a StreamReader, splits it into columns based on the defined separator (SplitChar), creates JSON objects for each row while handling headers accordingly, then appends these entries to a StringBuilder. Finally, it returns the complete JSON array represented as a string.

ToJson(string content, Options options)

This method takes a CSV-formatted string and an Options instance. It splits this input by newline characters (Environment.NewLine), processes each line similar to ToJsonAsync(), but does not support asynchronous operation. The result is returned as a JSON array string.

PrettyPrintJson(string json)

This utility method accepts a raw JSON-formatted string and returns it in a more readable, "prettified" format with indentation. It deserializes the input using JsonSerializer, applies new options to enable indenting (WriteIndented = true), then serializes back into a formatted string. Note that this method does not rely on any custom class attributes or annotations within JSON data.

Usage Example

Here's an example of how you can use the Csv2Json library:

var csvData = "Name, Age\nJohn Doe, 30"; // Sample CSV input string (headers included)
var options = new Csv2Json.Options
{
    ContainsHeader = true,
    UseAvailableHeader = true,
};

string jsonOutput = Csv2Json.ToJson(csvData, options);
Console.WriteLine(jsonOutput);

This example would output the following JSON:

[{"Name":"John Doe","Age":"30"}]

Source Code Structure

The library is structured into an Options class and a static Csv2Json class, with all related methods defined within it. The CreateFieldNames(), AddJsonEntry() extension method for StringBuilder, and the utility function PrettyPrintJson(string json) are used to facilitate CSV-to-JSON conversion operations.

Conclusion

The Csv2Json library provides a comprehensive, flexible solution for converting CSV data into JSON format in C# applications. With support for header handling and prettified output, this utility class can be easily integrated and customized to fit various use cases.