How Do I Parse Only Part of YAML Using YamlDotNet?

You can use the DeserializerBuilder to configure a deserializer that only parses the section you’re interested in.

Install YamlDotNet:

Make sure you have the YamlDotNet package installed. You can install it via NuGet package manager in Visual Studio or using the command line:
dotnet add package YamlDotNet

Define the Classes:

Define the C# classes that represent the structure of the YAML data you want to parse.

example:

public class ConfigOne
{
    public string Name { get; set; }
    public string Stuff { get; set; }
}

Read and Parse the YAML:

You will need to read the YAML content, extract the part you are interested in, and then deserialize it using YamlDotNet.

example:

using System;
using YamlDotNet.Serialization;
using YamlDotNet.Serialization.NamingConventions;

public class ConfigOne
{
    public string Name { get; set; }
    public string Stuff { get; set; }
}
class Program
{
    static void Main()
    {
        var yaml = @"
config_one:
  name: foo
  stuff: value

config_two:
  name: bar
  random: value";

        // Parse the YAML document
        var deserializer = new DeserializerBuilder()
            .WithNamingConvention(CamelCaseNamingConvention.Instance)
            .Build();

        var yamlObject = deserializer.Deserialize>(yaml);

        // Extract the part you are interested in
        var configOnePart = yamlObject["config_one"].ToString();

        // Deserialize the extracted part into the desired object
        var configOneDeserializer = new DeserializerBuilder()
            .WithNamingConvention(CamelCaseNamingConvention.Instance)
            .Build();

        var configOne = configOneDeserializer.Deserialize(configOnePart);

        // Output the result
        Console.WriteLine($"Name: {configOne.Name}, Stuff: {configOne.Stuff}");
    }
}

Explanation

1. Read the YAML content: The YAML content is stored in a string variable yaml.
2. Deserialize the YAML into a dictionary: The first deserialization step converts the YAML into a dictionary where each top-level key (like config_one and config_two) maps to an object. This uses the Dictionary type.
3. Extract the specific part: After the YAML is deserialized into a dictionary, you can access the part of the YAML you are interested in (in this case, config_one). The value of config_one is still in YAML format and needs to be converted to a string.
4. Deserialize the specific part: Finally, you use another deserializer to convert the extracted YAML string into an instance of ConfigOne.

Notes

The NamingConvention is set to CamelCaseNamingConvention to match the C# property naming style.

The extracted config_one part is converted to a string using .ToString(). Depending on the deserializer, you may need to use Serialize method to get a proper YAML string if direct conversion does not work.