JsonSerializer.Deserialize is returning empty object

Question

I have a webapi that returns some Json:

{"id":9,"businessName":"dummy","address":"pluto","products":[
{"id":762,"description":"Centralized needs-based website","price":1281.24,"stock":1600,"categories":[],"factory":null},
{"id":1027,"description":"Realigned 6th generation knowledge base","price":2398.16,"stock":19583,"categories":[],"factory":null},
{"id":1392,"description":"User-centric zero administration array","price":998.07,"stock":6124,"categories":[],"factory":null},
{"id":1800,"description":"Team-oriented reciprocal core","price":4422.95,"stock":17372,"categories":[],"factory":null},
{"id":2763,"description":"Sharable needs-based hierarchy","price":4122.98,"stock":17397,"categories":[],"factory":null},
{"id":6189,"description":"Re-engineered hybrid emulation","price":395.09,"stock":532,"categories":[],"factory":null}
]}

I then try to deserialize using:

using var response = await _httpClient.GetAsync($"{GetApiRouteFromEntity(entity)}/{entity.GetId()}");
        response.EnsureSuccessStatusCode();
        var responseContent = await response.Content.ReadAsStringAsync();
        T? item = JsonSerializer.Deserialize<T>(responseContent);

but this gives me an empty Factory with id 0 and all the other attributes to null

Factory.cs

public class Factory : EntityBase
    {
        [DisplayName("ID")]
        public int Id { get; set; }

        [DisplayName("Nome Business")]
        public string? BusinessName { get; set; }

        [DisplayName("Indirizzo")]
        public string? Address { get; set; }

        [DisplayName("Prodotti")] 
        public virtual ICollection<Product> Products { get; set; }
        
        public override string ToString()
        {
            return $"[{Id}] {BusinessName}";
        }
    }

Product.cs

public class Product : EntityBase
    {
        [DisplayName("ID")]
        public int Id { get; set; }

        [DisplayName("Descrizione")]
        public string? Description { get; set; }

        [DisplayName("Prezzo")]
        public float Price { get; set; }

        [DisplayName("Magazzino")]
        public int Stock { get; set; }

        [DisplayName("Categorie")]
        public virtual ICollection<Category> Categories { get; set; }

        [DisplayName("Fabbrica")]
        public virtual Factory Factory { get; set; }

        public override string ToString()
        {
            return $"[{Id}] {Description}";
        }
    }

EntityBase.cs

public abstract class EntityBase
    {
        public virtual object GetId()
        {
            return GetType().GetProperty("Id").GetValue(this);
        }
    }

i guess its because the factory prop in the products is null but idk how to work around that

Answer 1

The JSON keys are all camel case but the props in your classes are written in pascal case. E.g. businessName vs. BusinessName. Hence JsonSerializer can't match them.

You can initialize the serializer like this to ignore the differences in casing:

var options = new JsonSerializerOptions
{
    PropertyNameCaseInsensitive = true
};
T? item = JsonSerializer.Deserialize<T>(responseContent, options);

See the docs for further info: https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json-character-casing

Answer 2

From the docs:

By default, property names and dictionary keys are unchanged in the JSON output, including case.

You can specify the property naming policy:

T? item = JsonSerializer.Deserialize<T>(responseContent, new JsonSerializerOptions
{
    PropertyNamingPolicy = JsonNamingPolicy.CamelCase
});

to use camel case for all JSON property names, or mark all needed properties with JsonPropertyNameAttibute containing correct name:

public class Factory : EntityBase
{
    [DisplayName("ID")]
    [JsonPropertyName("id")] // and so on
    public int Id { get; set; }
    ....
}

Or set JsonSerializerOptions.PropertyNameCaseInsensitive to true.