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Is there a way to convert static string class property to Dictionary in C#?

public static class somename
{
public const string abc = "abc 1";
public const string xyz = "xyz 2";
public const string vhj = "vhj 3";
}
I wanted to convert this into dictionary object and use this in foreach
Any idea?

You can declare a static readonly dictionary with an initializer, if that's what you mean:
public static readonly Dictionary<string, string> MyDict =
new Dictionary<string, string> {{"abc", "abc 1"}, {"xyz", "xyz 2"}, {"vhj", "vhj 3"}};
To generate it from the class you already have, you need to use reflection:
var constants = typeof(somename).GetFields(BindingFlags.Public | BindingFlags.Static | BindingFlags.FlattenHierarchy)
.Where(fi => fi.IsLiteral && !fi.IsInitOnly && fi.FieldType==typeof(string));
var myDict = new Dictionary<string, string>();
foreach (var c in constants)
{
myDict.Add(c.Name, (string)c.GetRawConstantValue());
}

You can't create const dictionary, but you can do it readonly:
public static class somename {
// We can't assign MyDictionary (readonly)
// We can't add, remove or change items (IReadOnlyDictionary)
public static readonly IReadOnlyDictionary<string, string> MyDictionary = new Dictionary<string, string>() {
{ "abc", "abc 1" },
{ "xyz", "xyz 2" },
{ "vhj", "vhj 3" },
};
}
I've exposed IReadOnlyDictionary<string, string> to prevent unwanted chageing like
somename.MyDictionary["abc"] = "pqr" // typo: `=` instead of `==`
If you want elaborated logic, you can put it into static constructor:
public static class somename {
public static readonly IReadOnlyDictionary<string, string> MyDictionary;
static someone() {
Dictionary<string, string> myDict = new();
myDict.Add("abc", ComputeAbc());
myDict.Add("xyz", ComputeXyz());
myDict.Add("vhj", ComputeVhj());
MyDictionary = myDict;
}
}
You can enumerate {Key, Value} pairs in foreach, e.g.
foreach (var pair in somename.MyDictionary) {
Console.WriteLine($"{pair.Key} == {pair.Value}");
}

As it was stated by many people on this thread you can't really map your static class with const fields to a dictionary with the same runtime guarantees. In order to understand the problem let's define three terms:
Const: It has a compile-time guarantee that its value can't be changed.
Readonly: It has a run-time guarantee that once it is initialized it can't be changed.
Immutable: It has a run-time guarantee that whenever you perform a modification operation then it creates a new version of the object.
Please also bear in mind that objects and collections are treated in a different way. For example if you mark a collection as readonly it means you can't change the reference of the collection to another collection or to null. But it does not prevent you to add/remove items to/from the collection.
That's there are ReadonlyDictionary and ImmutableDictionary.
The closest thing what you can get is to use ImmutableDictionary as an implementation and expose it as an IReadonlyDictionary.
public readonly IReadOnlyDictionary<string, string> somenames = new Dictionary<string, string>
{
{ "abc", "abc 1" },
{ "xyz", "xyz 2" },
{ "vhj", "vhj 3" }
}.ToImmutableDictionary();
There are several ways to build an immutable collections. Here I have listed a couple of options.

Only create dictionary once - and use that when dictionary is being called?

I am currently working on refactoring some code, where I have stumbled upon this static dictionary:
public static Dictionary<string, string> CountryNamesAndCodes()
{
var dictionary = new Dictionary<string, string>();
dictionary.Add("AF", "Afghanistan");
dictionary.Add("AL", "Albania");
dictionary.Add("DZ", "Algeria");
dictionary.Add("AD", "Andorra");
dictionary.Add("AO", "Angola");
dictionary.Add("AG", "Antigua and Barbuda");
dictionary.Add("AR", "Argentina");
dictionary.Add("AM", "Armenia");
...
}
Which first of all is defined in the service layer, and takes up a lot a space - 400 lines, and eventhough it is static, it seem to always recreate the dictionary, meaning making the static part of it redundant - or am I wrong?
how do I ensure that this is only created once, and everytime I call it, it make use of the same instance.

You are quite right, you can extract the local dictionary as a static member
I suggest something like this (field):
// static readonly (we want to create it once) field of
// IReadOnlyDictionary type - we want to read key value pairs after its creation
private static readonly IReadOnlyDictionary<string, string> countries =
// We may want to be nice and let ignore case for keys
new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) {
{ "AF", "Afghanistan" },
{ "AL", "Albania" },
{ "DZ", "Algeria" },
//TODO:Put all the other records here
};
or like this (property):
// static readonly (there's no "set") property of
// IReadOnlyDictionary type - we want just to read key value pairs after its creation
private static IReadOnlyDictionary<string, string> Countries { get; } =
new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase) {
{ "AF", "Afghanistan" },
{ "AL", "Albania" },
{ "DZ", "Algeria" },
//TODO:Put all the other records here
};

public static class Globals
{
static Dictionary<string, string>
CountryNamesAndCodes = new Dictionary<string, string>
{
{"AF", "Afghanistan"},
{"AL", "Albania"}
};
}
name = Globals.CountryNamesAndCodes["AF"];

how to get corresponding "Name"

I have a C# dictionary in which I have a corresponding NAME against the ID.
Dictionary<string, List<object>> dict = new Dictionary<string, List<object>>
{
{ "ID", new List<object> { "Id1", "Id2" } },
{ "NAME", new List<object> { "True", "False" } }
};
foreach (var id in dict["ID"])
{
Console.WriteLine(id);
//how to get corresponding "Name". For "Id1" = "True" and for "Id2" = "False"
}
In above code I loop through ID, but how to get corresponding NAME?

I think a better design would be to create a class with the two properties and then iterate. If you find yourself having to sync different data structures for simple data representations then I'd suggest rethinking the design.
public class MyClass
{
public string Id { get; set; }
public bool Name { get; set; }
}
And then hold a List<MyClass> which when you iterate:
foreach (var item in list)
{
// Now access item.Id, item.Name
}
The use of dictionaries is good when you have some sort of natural key for your data and you want to access access an item by that key. As the items are accessed via a hash function accessing by key is done in O(1) whereas searching in a list is O(n). However in your case you are iterating all items in any case so no need for dictionary and arranging the data in a class is a better design.
A bit about the differences and some references:
what is the difference between list<> and dictionary<> in c#
List vs ArrayList vs Dictionary vs Hashtable vs Stack vs Queue?

If you do have control over dictionary data it's best to either use Gilad's answer and store everything in List<MyClass> or to use Dictionary<string, bool> :
Dictionary<string, bool> dict = new Dictionary<string, bool>()
{
{ "Id1", true }, { "Id2", false },
};
But if you do not have control over format of this data and get it as a dictionary from somewhere (for example web service) you could utilize .Zip method to convert this dictionary into one list of either anonymous objects/custom class or Tuples, where Item1 is Id and Item2 is value:
// anonymous object
var data = dict["ID"].Zip(dict["NAME"], (x, y) => new
{
ID = x,
NAME = y
}).ToList();
// tuple
// List<Tuple<object, object>> data = dict["ID"].Zip(dict["NAME"], Tuple.Create).ToList();
foreach (var obj in data)
{
Console.WriteLine(obj.ID + " " obj.NAME);
}

The other answers are probably what you should do to better structure your code. However, if you need to stick to your original use case, you could do something like this:
//Depending on what you're dealing with: Dictionary<string, List<string>>
Dictionary<string, List<object>> dict = new Dictionary<string, List<object>>{
{"ID", new List<object>{"Id1", "Id2"}},
{"NAME", new List<object>{"True", "False"}}
};
foreach(var v in dict.Keys){
Console.WriteLine($"{v} = {string.Join(",", dict[v])}");
}
//Output:
//ID = Id1,Id2
//NAME = True,False

Even if you have the just the mapping of ID and Name you can have very simple variable
Dictionary<string,string> lookup = new Dictionary<string,string>();
lookup.Add("ID1","True")
and if Name is Boolean type then replace string to bool in the
Dictionary<string,bool> lookup = new Dictionary<string,bool>();

Looping through dictionary object

I am very new to .NET, used to working in PHP. I need to iterate via foreach through a dictionary of objects. My setup is an MVC4 app.
The Model looks like this:
public class TestModels
{
Dictionary<int, dynamic> sp = new Dictionary<int, dynamic>
{
{1, new {name="abc", age="1"}},
{2, new {name="def", age="2"}}
}
}
Controller:
public class TestController : Controller
{
Models.TestModels obj = new Models.TestModels();
}
How do I loop through the obj object and retrieve the values of the dictionary and print them in the view?

One way is to loop through the keys of the dictionary, which I recommend:
foreach(int key in sp.Keys)
dynamic value = sp[key];
Another way, is to loop through the dictionary as a sequence of pairs:
foreach(KeyValuePair<int, dynamic> pair in sp)
{
int key = pair.Key;
dynamic value = pair.Value;
}
I recommend the first approach, because you can have more control over the order of items retrieved if you decorate the Keys property with proper LINQ statements, e.g., sp.Keys.OrderBy(x => x) helps you retrieve the items in ascending order of the key. Note that Dictionary uses a hash table data structure internally, therefore if you use the second method the order of items is not easily predictable.
Update (01 Dec 2016): replaced vars with actual types to make the answer more clear.

It depends on what you are after in the Dictionary
Models.TestModels obj = new Models.TestModels();
foreach (var keyValuPair in obj.sp)
{
// KeyValuePair<int, dynamic>
}
foreach (var key in obj.sp.Keys)
{
// Int
}
foreach (var value in obj.sp.Values)
{
// dynamic
}

You can do it like this.
Models.TestModels obj = new Models.TestModels();
foreach (var item in obj.sp)
{
Console.Write(item.Key);
Console.Write(item.Value.name);
Console.Write(item.Value.age);
}
The problem you most likely have right now is that the collection is private. If you add public to the beginning of this line
Dictionary<int, dynamic> sp = new Dictionary<int, dynamic>
You should be able to access it from the function inside your controller.
Edit: Adding functional example of the full TestModels implementation.
Your TestModels class should look something like this.
public class TestModels
{
public Dictionary<int, dynamic> sp = new Dictionary<int, dynamic>();
public TestModels()
{
sp.Add(0, new {name="Test One", age=5});
sp.Add(1, new {name="Test Two", age=7});
}
}
You probably want to read up on the dynamic keyword as well.

public class TestModels
{
public Dictionary<int, dynamic> sp = new Dictionary<int, dynamic>();
public TestModels()
{
sp.Add(0, new {name="Test One", age=5});
sp.Add(1, new {name="Test Two", age=7});
}
}

How to copy list of dictionaries

I have two dictionaries. When I change a value in dictionary 1, the same change appears in dictionary 2. How do I change a value only in dictionary 1, not in dictionary 2 as well?
List<Dictionary<string, string>> ld1 = new List<Dictionary<string, string>>();
Dictionary<string, string> d1 = new Dictionary<string,string>();
d1.Add("Text", "Value1");
d1.Add("Format", "Value2");
ld1.Add(d1);
List<Dictionary<string, string>> ld2 = new List<Dictionary<string, string>>(ld1);
// ld2 = ld1
ld1[0]["Text"] = "Eulav"; // should: change only in the first dictionary
// actually: changes in the second dictionary as well
Console.WriteLine(ld1[0]["Text"]);
Console.WriteLine(ld2[0]["Text"]);
Outputs
Eulav
Eulav

You only create a new list but the items in that list reference the same objects (dictionaries), so you need to create a copy of each item as well:
var ld2 = new List<Dictionary<string, string>>();
foreach (var dict in ld1)
{
ld2.Add(new Dictionary<string, string>(dict));
}

If you want to have two shallow copies of a particular Dictionary<TKey, TValue> then just use the constructor to create a copy
Dictionary<string, string> ld1 = ...;
Dictionary<string, string> ld2 = new Dictionary<string, string>(ld1);
Note: In this particular case it will be a deep copy since string is immutable and has no child data which needs to be deeply copied

The point to remember here is that though you are creating two instances (Two distinct memory allocations) of List, you are only creating "one" instance of Dictionary.
Thus, both the lists have the same memory pointer, pointing to the same dictionary. And it is obvious that the change in one will update the other too.
As suggested by others, here you need to create one more instance of Dictinary (A distinct memory allocation) and copy the values of the first one to it.
Dictionary<string, string> ld2 = new Dictionary<string, string>(ld1);
Doing this will store different instances in list and changes in one will not effect other.

user1158781 in order do it with non inmutable objects like strings, you will have to clone every element of the dictionary to a new one.
You can implement the IClonable interface. I leave a litle example:
class Program
{
static void Main(string[] args)
{
Dictionary<int, Person> dic1 = new Dictionary<int, Person>();
dic1.Add(0, new Person { Name = "user1158781" });
Dictionary<int, Person> dic2 = new Dictionary<int, Person>();
foreach (var item in dic1)
{
dic2.Add(item.Key, (Person)item.Value.Clone());
}
dic1[0].Name = "gz";
Console.WriteLine(dic1[0].Name);
Console.WriteLine(dic2[0].Name);
}
class Person : ICloneable
{
public string Name { get; set; }
public object Clone()
{
return new Person { Name = this.Name };
}
}
}