C#•9mo ago

Json Serializing And Deserializing Practice Errors

I am practicing Json Serializing rightnow, but I got stuck on this for the last day.
I always get this error, and I just want 1 thing, save the ingredients, and load it.

using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace Cookie_Cookbook.Recipe.Ingredient
{
    public static class IngredientManagement
    {
        public static void ShowCurrentRecipes(List<Ingredient> list)
        {
            if (list.Count == 0)
            {
                Console.WriteLine("There is no recipes added.");
            }
            else
            {
                Console.WriteLine("Recipe Added: ");
                foreach (Ingredient recipe in list)
                {
                    Console.WriteLine($"{recipe.Name}:{recipe.Instructions}");
                }
            }
        }
        public static void ShowIngredients()
        {
            Console.WriteLine("1. Wheat flour\n2. Coconut flour\n3. Butter\n4. Chocolate\n5. Sugar\n6. Cardamom\n7. Cinnamon\n8. Cocoa powder");
        }
        private static readonly string filePath = "recipe.json";
        public static void Save(List<Ingredient> list)
        {
            string toJson = JsonSerializer.Serialize(list);
            File.WriteAllText(filePath, toJson);
        }
        public static List<Ingredient> Load()
        {
            if (File.Exists(filePath))
            {
                string jsonData = File.ReadAllText(filePath);
                return JsonSerializer.Deserialize<List<Ingredient>>(jsonData) ?? new List<Ingredient>();
            }
            return new List<Ingredient>();
        }


    }
}

System.NotSupportedException: 'Deserialization of types without a parameterless constructor, a singular parameterized constructor, or a parameterized constructor annotated with 'JsonConstructorAttribute' is not supported. Type 'Cookie_Cookbook.Recipe.Ingredient.Ingredient'. Path: $[0] | LineNumber: 0 | BytePositionInLine: 2.'

using System.Collections.Generic;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace Cookie_Cookbook.Recipe.Ingredient
{
    public static class IngredientManagement
    {
        public static void ShowCurrentRecipes(List<Ingredient> list)
        {
            if (list.Count == 0)
            {
                Console.WriteLine("There is no recipes added.");
            }
            else
            {
                Console.WriteLine("Recipe Added: ");
                foreach (Ingredient recipe in list)
                {
                    Console.WriteLine($"{recipe.Name}:{recipe.Instructions}");
                }
            }
        }
        public static void ShowIngredients()
        {
            Console.WriteLine("1. Wheat flour\n2. Coconut flour\n3. Butter\n4. Chocolate\n5. Sugar\n6. Cardamom\n7. Cinnamon\n8. Cocoa powder");
        }
        private static readonly string filePath = "recipe.json";
        public static void Save(List<Ingredient> list)
        {
            string toJson = JsonSerializer.Serialize(list);
            File.WriteAllText(filePath, toJson);
        }
        public static List<Ingredient> Load()
        {
            if (File.Exists(filePath))
            {
                string jsonData = File.ReadAllText(filePath);
                return JsonSerializer.Deserialize<List<Ingredient>>(jsonData) ?? new List<Ingredient>();
            }
            return new List<Ingredient>();
        }


    }
}

System.NotSupportedException: 'Deserialization of types without a parameterless constructor, a singular parameterized constructor, or a parameterized constructor annotated with 'JsonConstructorAttribute' is not supported. Type 'Cookie_Cookbook.Recipe.Ingredient.Ingredient'. Path: $[0] | LineNumber: 0 | BytePositionInLine: 2.'

KIRA BELMONTOP•3/27/25, 4:09 AM

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace Cookie_Cookbook.Recipe.Ingredient
{
    public abstract class Ingredient
    {
        public abstract string Name { get;}
        public abstract int ID { get;}
        public virtual string Instructions => "Add to other ingredients.";
        public Ingredient()
        {
            
        }
    }   

}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.Json;
using System.Threading.Tasks;

namespace Cookie_Cookbook.Recipe.Ingredient
{
    public abstract class Ingredient
    {
        public abstract string Name { get;}
        public abstract int ID { get;}
        public virtual string Instructions => "Add to other ingredients.";
        public Ingredient()
        {
            
        }
    }   

}

this is the Ingredient Class

jcotton42•3/27/25, 4:09 AM

(you repasted IngredientManagement)

Angius•3/27/25, 4:09 AM

Well, the error is quite clear

jcotton42•3/27/25, 4:10 AM

The most direct solution to your problem is polymorphic serialization https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/polymorphism

How to serialize properties of derived classes with System.Text.Jso...

Learn how to serialize polymorphic objects while serializing to and deserializing from JSON in .NET.

Jjcotton42 The most direct solution to your problem is polymorphic serialization https://le...

KIRA BELMONTOP•3/27/25, 4:11 AM

is this intermediate thing or beginners?

KIRA BELMONTOP•3/27/25, 4:11 AM

i need to get the basics of this first

jcotton42•3/27/25, 4:11 AM

uh, intermediate i guess

Angius•3/27/25, 4:11 AM

Intermediate I'd say

jcotton42•3/27/25, 4:11 AM

but if you want to serialize derived types into JSON, that's what you have to do

KIRA BELMONTOP•3/27/25, 4:13 AM

this Ingredient is a class that has 2 sub classes, and all other objects created will be from these 2, either inherits from Ingredient class or the other 2 sub classes that also inherit from Ingredient class

KIRA BELMONTOP•3/27/25, 4:13 AM

will I find the solution here?

KIRA BELMONTOP•3/27/25, 4:14 AM

because I want to understand the basics of Json serialization at least, like how to do it properly and what exactly does it need, what is a file path and why we use it and these stuff

Angius•3/27/25, 4:15 AM

Either get rid of that inheritance structure, or do the polymorphic serialization

jcotton42•3/27/25, 4:15 AM

Well, if you want to stick to the absolute basics, you'll need to drop the inheritance.

Angius•3/27/25, 4:15 AM

Two options, really

Jjcotton42 Well, if you want to stick to the absolute basics, you'll need to drop the inher...

KIRA BELMONTOP•3/27/25, 4:15 AM

what do u mean

jcotton42•3/27/25, 4:15 AM

Because with inheritance, you need to tell the JSON serializer your entire inheritance hierarchy up front.
Otherwise it can't know what type the JSON represents when it comes time to deserialize.

jcotton42•3/27/25, 4:16 AM

If you're asking it to deserialize as a base type.

KIRA BELMONTOP•3/27/25, 4:17 AM

Is there a video that explains the basics of this?

GrabYourPitchforks•3/27/25, 4:18 AM

To cotton's point, consider that the deserializer is going to try doing something equivalent to this:

List<Ingredient> list = new List<Ingredient>();
list.Add(new Ingredient()); // <-- ERROR: cannot instantiate an abstract class

List<Ingredient> list = new List<Ingredient>();
list.Add(new Ingredient()); // <-- ERROR: cannot instantiate an abstract class

GrabYourPitchforks•3/27/25, 4:18 AM

So you need to configure the deserializer to tell it the equivalent of "don't say

new Ingredient(...)

new Ingredient(...)

. Say

new MyDerivedClass(...)

new MyDerivedClass(...)

instead!"

GrabYourPitchforks•3/27/25, 4:19 AM

But polymorphism is something of an advanced topic when it comes to deserialization, which is why my earlier recommendation was to avoid it if there's any possible way for you to do so.

GrabYourPitchforks•3/27/25, 4:19 AM

For example, do you really need lots of derived types hanging off the Ingredient class?

GrabYourPitchforks•3/27/25, 4:20 AM

Can't you take Name, Id, Instructions as constructor parameters and just have a single data type?

KIRA BELMONTOP•3/27/25, 4:20 AM

Not really, i was practicing inheriting and interfaces with a udemy course and they did the same, but they did not have to do the polymorphism serialaization

GGrabYourPitchforks Can't you take _Name_, _Id_, _Instructions_ as constructor parameters and just h...

KIRA BELMONTOP•3/27/25, 4:21 AM

Idk, i will send you how the program should be

Jjcotton42 The most direct solution to your problem is polymorphic serialization https://le...

GrabYourPitchforks•3/27/25, 4:22 AM

^^^ But if you really need to deserialize polymorphic classes, this link gives you all the details. The example at the very top of the document should get you started.

KIRA BELMONTOP•3/27/25, 4:22 AM

Welcome To The Recipes Adder!
Type The ID To Add The Recipe
Type Any Key Else To Finish

Wheat flour
Coconut flour
Butter
Chocolate
Sugar
Cardamom
Cinnamon
Cocoa powder
1
Type The ID To Add An Ingredient
2
Type The ID To Add An Ingredient
3
Type The ID To Add An Ingredient

Recipe Added:
Wheat Flour:Sieve. Add to other ingredients.
Coconut Flour:Sieve. Add to other ingredients.
Butter:Melt on low heat. Add to other ingredients.

Press any ket to close

KIRA BELMONTOP•3/27/25, 4:23 AM

this is the output, but after that, I want it to load all the recipes I saved and print it at the start

jcotton42•3/27/25, 4:23 AM

What necessitates the use of inheritance there?

Angius•3/27/25, 4:23 AM

Not sure why any inheritance is involved here tbh

KIRA BELMONTOP•3/27/25, 4:23 AM

cmon guys =(

KIRA BELMONTOP•3/27/25, 4:24 AM

so what, should i just avoid this assignment and go to the next section or what?

jcotton42•3/27/25, 4:24 AM

Does the assignment require mixing JSON and inheritance?

KIRA BELMONTOP•3/27/25, 4:24 AM

becuase i want to know how to save and load stuff later

Jjcotton42 Does the assignment require mixing JSON and inheritance?

Angius•3/27/25, 4:24 AM

You're saying everything I want to say just a split second before me :KEKW:

Jjcotton42 Does the assignment require mixing JSON and inheritance?

KIRA BELMONTOP•3/27/25, 4:25 AM

yes, but as I said in the video didn't have any problem with that, she went with a different aproach so this could be the reason

KIRA BELMONTOP•3/27/25, 4:25 AM

but the problem is, she didn't even explain how to do it properly, just a brief introduction to Json and boom, do the assignment

GrabYourPitchforks•3/27/25, 4:26 AM

I'll say: it is very uncommon to mix serialization + inheritance. It really is an advanced scenario. Which is why we're all perplexed as to why you're stating both that you've never worked with this type of serialization before and that you have to use inheritance.

GrabYourPitchforks•3/27/25, 4:26 AM

Like, you jumped straight to a 300-level concept without going through 100-level or 200-level introductions.

KIRA BELMONTOP•3/27/25, 4:27 AM

I guess that's why I was setting all day trying to figure it out

GrabYourPitchforks•3/27/25, 4:27 AM

Hah

Angius•3/27/25, 4:27 AM

If the assignment doesn't have you serialize those recipes, don't serialize them

Angius•3/27/25, 4:27 AM

Better yet: make your own version, on the side

KIRA BELMONTOP•3/27/25, 4:27 AM

maybe talked with gpt for 3 hours and still not that much

Angius•3/27/25, 4:27 AM

Without inheritance and with serialization

GrabYourPitchforks•3/27/25, 4:27 AM

Don't take it as a personal failing! It's just that you've taken on an advanced challenge.

Angius•3/27/25, 4:28 AM

Try to figure it out, based on what you know, but without the limitations imposed by the course

GrabYourPitchforks•3/27/25, 4:28 AM

Try it with very simple data types first. Change the Ingredient class just to have very simple get/set properties.

GrabYourPitchforks•3/27/25, 4:28 AM

And go from there.