C# yaml config

yaml is pretty good way to define config for an application rather than xml file. There are many libraries available for parsing yaml in C#. Two of the libraries i tried are: yamlconfig and sharpyaml. I liked the general concept behind yamlconfig but it wasn’t that good to just integrate and get started, so I chose sharpyaml over it.

The thing I liked about sharpyaml is how easy it is to get it going, I did not had much success with yamlconfig. Also yamlconfig looks far too fancy with Injectors and what not- to just get a simple yaml parsed. Anyway enough ranting.

Lets look at some code. This is the yaml file I want parsed:

 1
 2
 3
 4
 5
 6
 7
 8
 9
10

# mandatory settings
IndexDir: d:\indexdir
LogDir: c:\logs

# these should all be lower-case
FilterPattern:
 - pattern1
 - pattern2
 - pattern3

Here is some sample code C# to get this going: (I am assuming you have added reference to sharpyaml thru nuget)

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50

using SharpYaml.Serialization;
using System.IO;
using System.Text;

class Program
{
    private class Config
    {
        public String IndexDir { get; set; }
        public string LogDir { get; set; }
        public string[] FilterPattern { get; set; }
        public string[] SomeOptionalProp {get; set;}

        public override string ToString()
        {
            var bldr = new StringBuilder();

            bldr.AppendLine(string.Format("IndexDir - {0}", IndexDir));
            bldr.AppendLine(string.Format("LogDir - {0}", LogDir));
            if(FilterPattern != null)
            {
                bldr.AppendLine(string.Format("FilterPattern:"));
                foreach(var fp in FilterPattern)
                    bldr.AppendLine(string.Format("  - {0}", fp));
            }

            if(SomeOptionalProp != null)
            {
                bldr.AppendLine(string.Format("SomeOptionalProp:"));
                foreach(var fp in SomeOptionalProp)
                    bldr.AppendLine(string.Format("  - {0}", fp));
            }

            return bldr.ToString();
        }
    }

    static void Main(string[] args)
    {
        var yamlPath = "config.yml";
        var input = new StreamReader(yamlPath);

        var deserializer = new Serializer();
        var config = (Config)deserializer.Deserialize(input, typeof(Config));

        Console.WriteLine(config.ToString());
        Console.ReadKey();
    }
}

One of the things is to ensure that your Config class has to match yaml file. It’s okay to neglect a few properties in yaml, but anything extra on top of your class schema and parsing will fail. Other than that the code is pretty self-explanatory.

Lines 7-36: define the Config class whose object will contain data from parsed yaml file- think of it as schema for yaml.
Lines 43: create a new Serializer object and use it to read yaml from stream (line 41) Uses reflection internally to populate the fields of your class- see get and set for properties are not private.

I have overridden print method on Config class just to print out what it parsed:

1
2
3
4
5
6
IndexDir - d:\indexdir
LogDir - c:\logs
FilterPattern:
 - pattern1
 - pattern2
 - pattern3

That’s pretty much it..

misc