When using YamlDotNet Deserializing mechanism without specifying a target type,
we always get a either a Dictionary (mapping),a List of KeyValuePairs (list) or a single KeyValuePair/string (scalar).
The KeyValuePairs will either contain another Dictionary, another List or the actual value.
We now can implement a query functionality:
var data = new YamlQuery(yamlObject)
.On("pods") // parent
// this functionality could be implemented as well wihtout much effort
//.Where("ignore").Equals(true)
.Get("name") // propery
.ToList<string>();
Edit:
Multiple nested values
var data = new YamlQuery(yamlObject)
.On("ressources")
.On("pods")
.Get("name")
.ToList<string>();
Working example: https://dotnetfiddle.net/uNQPyl
using System.IO;
using System;
using System.Linq;
using YamlDotNet.Serialization;
using System.Collections.Generic;
using YamlDotNet.RepresentationModel;
namespace ConsoleApp1
{
public class Program
{
public static void Main()
{
object yamlObject;
using (var r = new StringReader(Program.Document))
yamlObject = new Deserializer().Deserialize(r);
var data = new YamlQuery(yamlObject)
.On("pods")
.Get("name")
.ToList<string>();
Console.WriteLine("all names of pods");
Console.WriteLine(string.Join(",", data));
data = new YamlQuery(yamlObject)
.On("ressources")
.On("pods")
.Get("name")
.ToList<string>();
Console.WriteLine("all names of pods in ressources");
Console.WriteLine(string.Join(",", data));
}
public class YamlQuery
{
private object yamlDic;
private string key;
private object current;
public YamlQuery(object yamlDic)
{
this.yamlDic = yamlDic;
}
public YamlQuery On(string key)
{
this.key = key;
this.current = query<object>(this.current ?? this.yamlDic, this.key, null);
return this;
}
public YamlQuery Get(string prop)
{
if (this.current == null)
throw new InvalidOperationException();
this.current = query<object>(this.current, null, prop, this.key);
return this;
}
public List<T> ToList<T>()
{
if (this.current == null)
throw new InvalidOperationException();
return (this.current as List<object>).Cast<T>().ToList();
}
private IEnumerable<T> query<T>(object _dic, string key, string prop, string fromKey = null)
{
var result = new List<T>();
if (_dic == null)
return result;
if (typeof(IDictionary<object, object>).IsAssignableFrom(_dic.GetType()))
{
var dic = (IDictionary<object, object>)_dic;
var d = dic.Cast<KeyValuePair<object, object>>();
foreach (var dd in d)
{
if (dd.Key as string == key)
{
if (prop == null)
{
result.Add((T)dd.Value);
} else
{
result.AddRange(query<T>(dd.Value, key, prop, dd.Key as string));
}
}
else if (fromKey == key && dd.Key as string == prop)
{
result.Add((T)dd.Value);
}
else
{
result.AddRange(query<T>(dd.Value, key, prop, dd.Key as string));
}
}
}
else if (typeof(IEnumerable<object>).IsAssignableFrom(_dic.GetType()))
{
var t = (IEnumerable<object>)_dic;
foreach (var tt in t)
{
result.AddRange(query<T>(tt, key, prop, key));
}
}
return result;
}
}
private const string Document = @"---
receipt: Oz-Ware Purchase Invoice
date: 2007-08-06
customer:
given: Dorothy
family: Gale
pods:
- name: pod1
descrip: Water Bucket (Filled)
price: 1.47
quantity: 4
- name: pod2
descrip: High Heeled ""Ruby"" Slippers
price: 100.27
quantity: 1
- name: pod3
descrip: High Heeled ""Ruby"" Slippers
ignore: true
quantity: 1
bill-to: &id001
street: |-
123 Tornado Alley
Suite 16
city: East Westville
state: KS
pods:
- name: pod4
descrip: High Heeled ""Ruby"" Slippers
price: 100.27
quantity:
ressources:
- pids:
- id: 1
- name: pid
- pods:
- name: pod5
descrip: High Heeled ""Ruby"" Slippers
price: 100.27
quantity:
- name: pod6
descrip: High Heeled ""Ruby"" Slippers
price: 100.27
quantity:
specialDelivery: >
Follow the Yellow Brick
Road to the Emerald City.
Pay no attention to the
man behind the curtain.
...";
}
}
