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What am I doing wrong when trying to deserialize json into a c# list?

I have a Product class:
class Product
{
public string Name;
}
A Product List class:
class ProductDataFile
{
public List<Product>? products;
}
And a class for loading json into these classes:
public void LoadProducts()
{
string jsonString = File.ReadAllText(FileLoc);
ProductDataFile? productDataFile= JsonSerializer.Deserialize<ProductDataFile>(jsonString);
var ProductName = productDataFile.products.First().Name;
}
This throws a "System.ArgumentNullException: Value cannot be null. (Parameter 'source')". I used the debugger and products is null, so that seems to be the problem.
My Json looks something like this:
{
"listOfProducts": "List of products",
"products": [
{
"Name": "product one"
}
]
}
```

The library Newtonsoft.json method of JsonSerializer.Deserialize need to use properties instead of fields, otherwise you might not Deserialize anything from your JSON data.
class Product
{
public string Name {get;set;}
}
class ProductDataFile
{
public List<Product>? products {get;set;}
}
I would suggest you use json2csharp, it can easy to get the model by JSON and make sure it will be work.

Create a JSON object using properties of a C# class

I'm trying to construct a request body for a REST api call, and I need to create a JSON object with the list of properties I want to get back.
For eg: I have this C# object that I want to get back:
public class SomeProperties
{
public string TicketNumber { get; set; }
public Driver Driver { get; set; }
}
public class Driver
{
public string Name { get; set; }
}
To get this back, I need to put these properties in a JSON request body like this:
"properties": [
"ticketNumber",
"driver.name"
]
My attempt looks like this:
private string FetchProperties()
{
var fetchProperties = new
{
properties = new List<string>
{
"ticketNumber",
"driver.name"
}
};
var jsonResult = JsonConvert.SerializeObject(fetchProperties, Formatting.None);
return jsonResult;
}
But I don't want to hard code the properties like that.
So is there any way I can use property names from the object I want, to put in the list of strings that I made in the method above?
Thank You!

If I understand correctly,you need Metadata of model.
if you use EntityFramework, you can get metadata of your model
from this Code
and call BuildJsonMetadata() function
and if you use other mapper, I dont see any exist tool for generate metadata of model and you must generate it handly
somthing like this

First of, if you serialize the class you have (SomeProperties), you will not get driver.name. Instead you will get a string like this one that shows driver as an object,
{
properties : {
"ticketNumber" : "stringvalue",
"driver" : {
"name" : "stringValue"
}
}
}
That said, if you are interested in getting a json like this,
"properties": [
"ticketNumber",
"driver.name"
]
you will need a class (very simple one at that) that contains only a list of strings. properties is not an array of objects, but simply strings. From the looks of the FetchProperties method, you are creating an object with fetchProperties as the RootObject. Try something like this,
public class MyClass
{
[JsonProperty("fetchProperties")]
public Fetch FetchProperties { get; set; }
}
public class Fetch
{
[JsonProperty("properties")]
public List<string> Properties { get; set; }
}
private string FetchProperties()
{
MyClass obj = new MyClass()
{
FetchProperties = new Fetch()
{
Properties = new List<string>() { "ticketNumber", "driver.Name" }
}
};
return JsonConvert.SerializeObject(obj); // Formatting.None is by default
}
Now its your choice to hard code these values or, pass them as arguments or use a local variable that contains a list of all the strings you intend to store as "properties". You cant use enums because of violation in naming convention (driver.name) so these options should suffice.

How to mark certain property as required in json content

I am writing an application where I do need to handle some scenarios beforehand in my controller class like certain property must have been provided otherwise status code would be BadRequest. Here is my class lookalike.
public class MyClass
{
[Required]
public IEnumerable<NewObject> NewObjects { get; set; }
}
public class NewObject : INewObject
{
public NewObject(string typeName, IEnumerable<Property> properties)
{
TypeName = typeName;
Properties = properties;
}
[JsonProperty(Required = Required.Always)]
public string TypeName { get; }
public IEnumerable<IProperty> Properties { get; }
}
public interface IProperty
{
string Name { get; }
object Value { get; }
}
Now though I have marked TypeName as required property and if I do not pass that in json content while sending request from swagger, json deserialization doesn't fail. I tried to search but I got an answer that setting Required to Always should work.
Below is the Json Content I am passing through swagger:
{
"NewObjects": [
{
"Properties": [
{
"Name": "string",
"Value": ''
}
]
}
]
}
I wrote below piece of code too by looking at one of the solution:
var config = new HttpConfiguration();
var jsonFormatter = config.Formatters.JsonFormatter;
jsonFormatter.SerializerSettings.MissingMemberHandling = MissingMemberHandling.Error;
config.MapHttpAttributeRoutes();
Still it's not working:
Note: I am using Newtonsoft.Json version 11.0.1
This seems to be swagger issue because when I serialize input C# object and when again deserialize it, I am getting proper error.
For example in my controller class if I say:
var input2 = JsonConvert.DeserializeObject<MyClass>(JsonConvert.SerializeObject(input))
Then input2 throws an exception.

You can take a look at FluentValidation. If I am not mistaken it is designed to validate data in jsons forms specifically.
using FluentValidation;
public CertainActionValidator()
{
RuleFor(x => x.PropertyName).NotEmpty()
}
You can add plenty of additional conditions in there.

JSON Root Node - Different From Class Name

I need to get my JSON output looking like this:
{
"User": {
"Id" : "1",
"FirstName" : "John",
"LastName" : "Doe",
... etc
My first issue is that the class name being serialized here is called Person not User, and I am not able to change that. But the JSON needs User.
Secondly, my Web API method is not returning a root node here at all, what exactly am I doing wrong?
My JSON looks like this:
{"Id":1,"BossId":null,"Title":"CEO","GivenName":"Doe", ... etc
This is so badly formatted that even my Chrome extension to make JSON pretty doesn't recognize this stuff.
Here's my Web API controller to get a user by ID, which is resulting in the above:
[Route("{id:int}")]
public HttpResponseMessage GetPerson(int id) {
Person person = repository.Get(id);
if (person == null) {
throw new HttpResponseException(HttpStatusCode.NotFound);
}
return Request.CreateResponse(HttpStatusCode.OK, person);
}
I am also going to have to map class properties to different names here, which is a separate issue.
For example, the class has GivenName and FamilyName but the JSON needs FirstName and LastName. Is there an attribute I can apply to the property for this?
Any help would be appreciated.

ASP.NET WebApi uses JSON.NET for serialization to json. So you can change name in this way:
class Person
{
[JsonProperty(PropertyName = "LastName")]
public string FamilyName { get; set; }
...
}
EDIT
For add root element look at this answer. I didn't try this but looks nice.

Assuming you are using the Newtonsoft Json.Net, the most popular .Net Json serializer, following modifications are required:
Wrap the Person object inside a wrapper and assign a JsonProperty to it:
[JsonObject]
public class Wrapper
{
[JsonProperty("User")]
public Person Person {get; set;}
}
Now use the same JsonProperty inside the Person class too:
[JsonObject]
public class Person
{
[JsonProperty("FirstName")]
public string GivenName {get; set;}
[JsonProperty("LastName")]
public string FamilyName {get; set;}
... More Properties
}
Now while filling the response.following need to be done:
Wrapper w = new Wrapper();
w.Person = <assign Value>
return Request.CreateResponse(HttpStatusCode.OK, w);
One last thing Json unlike XML doesn't have a concept of a root node, it's nameless, that's why wrapper doesn't come anywhere and it would start from first object marked as User in this case, Json is a like an anonymous type in C#, internally a Key Value pair, since Keys are always string

Adding serialization information for MongoDB custom serializer

I have a class defined as follows:
class Person
{
public String Id { get; set; }
public String Name { get; set; }
public Person Mother { get; set; }
}
I've implemented a custom serializer for the Mother property to serialize the Id only. The final BSON would look something like this:
[{
"_id": "54df1095fa0bd7122cb2c550",
"name": "John",
"mother": { "_id": "54df1095fa0bd7122cb2c551" }
}]
If I try to execute a query to find a person with a given mother as follows:
var results = await collection.Find<Person> (p => p.Mother.Id == "...").ToListAsync ();
The driver complains with the following:
{"Unable to determine the serialization information for the expression: p.Mother.Id."}
Is there a way to add serialization info to the driver so it knows to call my custom serializer to deserialize Person for this type of query?

Yes, there are two interfaces you may implement to provide serialization information. IBsonDocumentSerializer and IBsonArraySerializer. In this case, you'll want to implement IBsonDocumentSerializer on your customer serializer and handle the GetMemberSerializationInfo call for the memberName Id.