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Nested list of constant strings in C#

Any way I can store this data in a clean way, and preferably use variable names instead of strings as keys to avoid typos? E.g. UNITED_STATES = "201" instead of "United States" = "201".
{
"countries": {
"id": "123",
"data" {
"United States": "201"
"Canada": "202",
}
},
"departments": { ... }
}
I started with KeyValuePairs like this, but nesting data in here seems like a bad idea.
private static readonly List<KeyValuePair<string, string>> CategoryIds = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("Countries", "123"),
new KeyValuePair<string, string>("Departments", "124")
};

Two approaches to deserialize JSON here.
Strong typing approach (good approach):
public class A
{
public B Countries {get;set;}
public C Departments {get;set;}
}
public class B
{
public int Id {get;set;}
public D Data {get;set;}
}
...
var result = JsonConvert.DeserializeObject<A>(json);
You create DTO objects manually and just expect them to deserialize successfully.
Dynamic approach (bad but sometimes acceptable approach):
dynamic result = JsonConvert.DeserializeObject(json);
var data = result.countries.data;
You create some "bag of things" (dynamic is basically a bunch of hierarchical Dictionary wrapped into syntax sugar cane), don't really care about all of them, and just want some of its properties.

Maybe you could use json.net JObject?
It allows you to work with dynamic objects and convert them to and from json strings
Documentation for JObject
https://www.newtonsoft.com/json/help/html/QueryingLINQtoJSON.htm
Nuget:
https://www.nuget.org/packages/Newtonsoft.Json/

You can use a dictionary<k,v> for this purpose along with a enum like below probably
enum CountryVal
{
UnitesStates,
Canada
}
With a model structure like
public class Countries
{
public string id { get; set; }
public Dictionary<CountryVal, int> Data { get; set; }
}
public class Departments
{
public string id { get; set; }
}
public class RootObject
{
public Countries countries { get; set; }
public Departments departments { get; set; }
}

You can create a public class as below and you can then call country value like CountriesConstants.UNITED_STATES in your code and if you need to change the value just update it in CountriesConstants class
public class CountriesConstants
{
public const string UNITED_STATES = "201";
public const string Canada = "202";
//Add More
}

NJsonSchema is a library that will enable you to generate code in csharp as well as few other languages from a standard json schema. It is very powerful and configurable, and can pave most of the way on your behalf. But as i said it will expect an standard json schema as for the source of generation.
var schema = NJsonSchema.JsonSchema4.FromFileAsync(filename);
var generator = new CSharpGenerator(schema.Result);
var file = generator.GenerateFile();
Above is the minimum amount of code required to generate csharp classes from json schema. you can define settings and pass to the generator function to service your special needs of course.
github page for this library:
NJsonSchema github
Nuget page:
NJsonSchema Nuget

Get tags names from json file as a variable in a class

I am using C# MVC
I am importing a Json file from a location to an Rest API. In order to display the data. the program needs to know the name of the tags.
I would like to know if there is a way to get the tags from the files in an array of strings and declare them via program instead of manually inputting them.
Current C# Code
public class Person
{
public int Id { get; set; }
public int SomeID { get; set; }
public int Number { get; set; }
public string Name { get; set; }
public string Address { get; set; }
}
Current Json File:
[{"Id":212,"SomeID":71,"Number":0,"Name":"Mr Jones Mones","Address":"21, street, city"}
So as mentioned this code words fine. But, as I am importing data, the tags may contain different information and I would like to have the public declaration in a way that I can import any file to the API and be able to edit and export it.
Thank you

If you use JSON.net you can parse out json into a JObject then iterate over it's properties like so, however each property value can be any type of object so you'd need to write something to either recursively listed out nested objects or check if values are strings and only take them if they are etc.
var obj = JObject.Parse("{ \"test\": \"test\", \"test1\": \"test1\", \"test2\": \"test2\" }");
foreach (var prop in obj.Properties())
{
Console.WriteLine(prop.Name);
}

You can use JsonConvert like this:
Person person = JsonConvert.DeserializeObject<Person>(jsonString);
Read the docs for JsonConvert for more info.

FileHelpers error: The field: 'k__BackingField' has the type: XXX that is not a system type, so this field need a CustomConverter

I need to read a CSV file with FileHelpers based on type, automatically generated by my MVC model. The model looks like this:
public partial class Merchant
{
public long Id { get; set; }
public string Name { get; set; }
public Nullable<int> Category { get; set; }
public virtual MerchantCategory MerchantCategory { get; set; }
}
The last field is obviously generated by a foreign key in database, referring to table MerchantCategories.
Then I attempt to create an instance of FileHelperEngine with this type:
var engine = new FileHelperEngine<Merchant>();
And get the following exception:
The field: 'k__BackingField' has the type: MerchantCategory that is not a system type, so this field need a CustomConverter ( Please Check the docs for more Info).
Actually I don't need this field at all for my import, so I tried to ignore it in derived class:
[DelimitedRecord(",")]
public class MerchantForImport : Merchant {
[FieldHidden]
new public MerchantCategory MerchantCategory;
}
var engine = new FileHelperEngine<MerchantForImport>();
And still the same error. I don't need this field at all, I don't want to implement any FieldConverter for it, I never asked for this k__BackingField and it's nowhere to be found in my code!
I can't call FileHelperEngine.Options.RemoveField() because the exception is thrown by the constructor.
Where does that come from? How do I get rid of it?

From a design perspective, I think you are going about it the wrong way. You are trying to use the Merchant class for two incompatible uses. Instead you should have two separate classes.
FileHelpers is a library for describing csv files so that you can import them easily. You should have a MerchantFileSpec for describing your file. It's really not a proper C# class - it may have: dummy fields to represent unused columns; lots of attributes [FieldNullValue], [FieldQuoted], [FieldConverter]; etc. It works best with public fields (a FileHelpers limitation which is not C# best practice), etc. It is a convenience syntax for describing the import file. It should not include any business logic or special constructors, or backing fields. Keep it as simple as possible.
Then you can have your MVC-generated Merchant class which is separate. Its purpose is to describe the merchant as required by the MVC framework, with foreign keys, ids, whatever.
Then you use a FileHelperEngine<MerchantFileSpec> to read the records into an array and map it to an enumerable of Merchant (via Linq or a library like AutoMapper).
Something like:
/// Your MVC-generated class. Add methods, getters, setters, whatever.
/// FileHelpers doesn't use this class.
class Merchant
{
public long Id { get; set; }
public string Name { get; set; }
public Nullable<int> Category { get; set; }
public virtual MerchantCategory MerchantCategory { get; set; }
}
/// This is the class FileHelpers will use
/// This class describes the CSV file only. Stick to whatever
/// syntax conventions are required by FileHelpers.
[DelimitedRecord(";")]
class ProductMerchantFileSpec
{
[FieldQuoted(QuoteMode.OptionalForRead)]
public long Id;
[FieldQuoted(QuoteMode.OptionalForRead)]
public string Name;
[FieldQuoted(QuoteMode.OptionalForRead)]
// Handle non-US formats such as , decimal points
// convert from inches to centimetres?
// you get the idea...
[FieldConverter(MyCustomizedCategoryConverter)] // you get the idea
public int Category;
}
class Program
{
static void Main(string[] args)
{
var engine = new FileHelperEngine<ProductMerchantFileSpec>();
var productMerchantRecords = engine.ReadFile(filePath);
var productMerchants = productMerchantRecords
.Select(x => new Merchant() { Id = x.Id, Name = x.Name, Category = x.Category });
}
}

I received this error specifically because my object (i.e. Merchant) was missing a column that existed in the source file. I was able to work around the issue prior to realizing the missing column by adding a new property to my object class public string[] MyProperty { get; set; }. This work-around help me realize a column was missing.
i.e..
public partial class Merchant
{
public long id { get; set; }
..
..
..
public string[] MyProperty { get; set; }
}

How to solve "Expected element name to be '_t', not 'number'."

I have a mongo model like this:
class ObjectA {
[BsonId(IdGenerator = typeof(BsonObjectIdGenerator))]
public BsonObjectId Id;
[BsonElement("number")]
public int Number { get; set; }
[BsonElement("b")]
public List<ObjectB> objectB { get; set; }
}
class ObjectB {
[BsonElement("someProperty")]
public string SomeProperty { get; set; }
}
My problem is when I aggregate the collection with {$unwind:objectB}. The result documencts have a unique object on the property objectB (not a list).
So the cast failes with the exception:
An error occurred while deserializing the ObjectB property of class
ObjectA: Expected element name to be '_t', not
'number'.
Do I have to create a new model for this or is there a easier way to solve it?

You could also choose to work with BsonDocument directly (but that is not strongly typed and more cumbersome to work with), e.g. (I'm using the simple Posts/Tags example here)
var aggregationResults = db.GetCollection("Posts").Aggregate().ResultDocuments;
foreach (var document in aggregationResults)
{
var tag = document.GetValue("Tags").AsString;
}
Unlike the normal query and projection operators, the aggregation framework may change the structure of your document. As you already pointed out, $unwind transforms a document that contains an array into a number of documents that each have a single value of the same name.
Another approach this is to indeed create a new type for this, so
class Post {
public List<string> Tags { get; set; }
...
would become
class PostAggregationResult {
public string Tags { get; set; }
...
That is very easy to work with, but if you have very various aggregation queries, you need a large number of classes which can be annoying.

Serializing object to XML to get list of tags named like field value

I have 2 classes:
public class LocalizationEntry
{
public List<TranslationPair> Translations
{
get;
set;
}
}
public class TranslationPair
{
public string Language
{
get;
set;
}
public string Translation
{
get;
set;
}
}
Is it possible to get such a XML using standard serializer?
<LocalizationEntry>
<Translations>
<EN>apple<EN>
<PL>jabłko<PL>
<DE>apfel<DE>
</Translations>
</LocalizationEntry>
I was thinking about something like XmlArrayItem(ElementName=this.Language) attribute but of course this construction is illegal apart from that attribute value cannot be determined in runtime.
Thanks for any help. Surely I can use other structure, but I'm curious is it possible.

To customise the element names is a pain; I would forget about XmlSerializer here, as you'd have to use IXmlSerializable which is a royal pain. I'd use XElement instead:
var source = new LocalizationEntry {
Translations = new List<TranslationPair> {
new TranslationPair {Language="EN", Translation="apple"},
new TranslationPair {Language="PL", Translation="jabłko"},
new TranslationPair {Language="DE", Translation="apfel"},
}
};
var el = new XElement("LocalizationEntry",
new XElement("Translations",
from pair in source.Translations
select new XElement(pair.Language, pair.Translation)));
var xml = el.ToString();

enter link description hereUse the XMLSerializer Object in the .NET Framework
Remember to put the Serializable Attribute on the Class Name
click this Link, i cant work out how to Add the Name of the URL sorry