Convert nested object Id to object when deserializing JSON-CodePudding

*** Edit: Clarified there are two, separate JSON files ***

I have two classes:

public class Phone  
{
     public int PhoneId  { get; set; }
     public string Name { get; set; }
     public Manufacturer PhoneManufacturer { get; set; }
}

public class Manufacturer  
{
    public int ManId  { get; set; }
    public string Name  { get; set; }
}

And two JSON files containing data for both classes:

phones.json:

[
   {
       "phoneId" : 45,
       "name": "S20",
       "phoneManufacturer":16
   }
]

manufacturers.json:

[
   {
       "manId" : 16,
       "name": "Samsung"      
   }
]

I use the following code to deserialize the phones objects:

string jsonString = File.ReadAllText("phones.json");
return JsonSerializer.Deserialize<List<Phone>>(jsonString, new JsonSerializerOptions { PropertyNameCaseInsensitive = true})!;

I want that when deserializing the Phones JSON to List<Phone>, the resulting objects will have its PhoneManufacturer property populated with the actual Manufacturer object.

When running the deserialization with the default parameters, I get an error that JSON cannot convert the value in the PhoneManufacturer property to a Manufacturer object, which makes sense since this is the object Id, and not the object itself.

How can I achieve that?

CodePudding user response：

You need to write a custom converter for manually mapping IDs to objects. There is a great series of Articles that cover this topic for both NewtonSoft & System.Text.Json: Working with JSON Series. The section labelled Multi-Value Type Collections is similar to what you are trying to do.

CodePudding user response：

If you are using System.Text.Json, and you don't mind modifying the class to add a new constructor, this is quite achievable as long as you have a collection of manufacturers available to the Phone constructor. Something like:

[JsonConstructor]
public Phone(int phoneId, string name, int phoneManufacturer)
{
    PhoneId = phoneId;
    Name = name;
    if(!ManufacturerDictionary.Contains(phoneManufacture)) throw new Exception();
    PhoneManufacturer = ManufacturerDictionary.[phoneManufacturer];
}