C#•14mo ago

❔ NewtownSoft.JSON and classes that need references to its owner

I have two classes. Class A owns instances of Class B. But each instance of Class B needs a reference back to the instance of Class A that created it. Can System.Text.Json.JsonSerializer do that?

62 Replies

JakenVeina•14mo ago

depends how it's structured

Will PittengerOP•14mo ago

Well, see the last posts in https://discord.com/channels/143867839282020352/1157002592119947374.

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JakenVeina•14mo ago

public class Parent
{
    public required string Name { get; init; }

    public required IReadOnlyList<Child> Children { get; init; }
}

public class Child
{
    public required string Name { get; init; }

    public required Parent Parent { get; init; }
}

public class Parent
{
    public required string Name { get; init; }

    public required IReadOnlyList<Child> Children { get; init; }
}

public class Child
{
    public required string Name { get; init; }

    public required Parent Parent { get; init; }
}

this ought to work, if you enable reference handling wouldn't work if you were going to, say, use constructor initialization, instead of init properties

Will PittengerOP•14mo ago

OK.

Will PittengerOP•14mo ago

So would that work even if the value is only a string? See the final example in https://discord.com/channels/143867839282020352/1157002592119947374.

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JakenVeina•14mo ago

even if what value is only a string? not sure what you mean

Will PittengerOP•14mo ago

The first sample here would produce the same results as the second:

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

[
  {
    "wrapped": "ss",
    "some other value": "default"
  },
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

[
  {
    "wrapped": "ss",
    "some other value": "default"
  },
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

JakenVeina•14mo ago

in what regard? produce how? what would produce that?

Will PittengerOP•14mo ago

Well, I was going to use an implicit typecast operator as was suggested in the thread I linked earlier, https://discord.com/channels/143867839282020352/1157002592119947374. But that operator can't work as it doesn't have a reference to the owner.

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Will PittengerOP•14mo ago

The string is a simplified version of the long form.

JakenVeina•14mo ago

okay, like what is the actual goal here are you trying to serialize JSON or deserialize?

Will PittengerOP•14mo ago

Deserialize.

JakenVeina•14mo ago

what's the JSON you want to deserialize?

Will PittengerOP•14mo ago

???? I showed you that above.

JakenVeina•14mo ago

not really you posted two snippets and said that "they produce the same result" which one represents JSON that you receive and need to deserialize? both of them?

Will PittengerOP•14mo ago

Well, both could.

JakenVeina•14mo ago

Will PittengerOP•14mo ago

They're both valid.

JakenVeina•14mo ago

and you're using Newtonsoft? or System.Text.Json?

Will PittengerOP•14mo ago

Yes. Well, I see System.Text.Json, but I had to install a package to get it.

JakenVeina•14mo ago

uhh, same as you did for Newtonsoft anyway, so the most straightforward implementation is...

public class MyJsonRecord
{
    [JsonProperty("wrapped")]
    public required string Wrapped { get; init; }

    [JsonProperty("some other value")]
    public required string SomeOtherValue {  get; init; }
}

public class MyJsonRecord
{
    [JsonProperty("wrapped")]
    public required string Wrapped { get; init; }

    [JsonProperty("some other value")]
    public required string SomeOtherValue {  get; init; }
}

var json1 = @"[""ss"",{""wrapped"": ""value"",""some other value"": ""value2""}]";
var json2 = @"[{""wrapped"": ""ss"",""some other value"": ""default""},{""wrapped"": ""value"",""some other value"": ""value2""}]";

var result1 = JsonConvert.DeserializeObject<List<object>>(json1);
var result2 = JsonConvert.DeserializeObject<List<object>>(json2);

var json1 = @"[""ss"",{""wrapped"": ""value"",""some other value"": ""value2""}]";
var json2 = @"[{""wrapped"": ""ss"",""some other value"": ""default""},{""wrapped"": ""value"",""some other value"": ""value2""}]";

var result1 = JsonConvert.DeserializeObject<List<object>>(json1);
var result2 = JsonConvert.DeserializeObject<List<object>>(json2);

Will PittengerOP•14mo ago

What about the owner field?

JakenVeina•14mo ago

what is "the owner field"?

Will PittengerOP•14mo ago

I told you the class in the list needs a reference to the object that owns it.

JakenVeina•14mo ago

which is what? you said that, but where is that represented in the JSON?

Will PittengerOP•14mo ago

It's more like:

C#
class Y
{
  // cooresponsds to the array in the file
  System.Collections.Generic.List<X> list = new();
}
class X
{
  public readonly Y owner;
  public required string Wrapped {get; init;}

  public required string SomeOtherValue{get; init;}
}

C#
class Y
{
  // cooresponsds to the array in the file
  System.Collections.Generic.List<X> list = new();
}
class X
{
  public readonly Y owner;
  public required string Wrapped {get; init;}

  public required string SomeOtherValue{get; init;}
}

JakenVeina•14mo ago

okay

Will PittengerOP•14mo ago

It isn't. I'm needing a way to pass it in.

JakenVeina•14mo ago

that would be the most effective thing to do, yes technically, you could build a whole custom JSON parser that is smart enough to populate it on construction but it's really not the job of the JSON parser, anyway that owner field isn't part of the data, it's part of your business model populate it in your business layer

Will PittengerOP•14mo ago

Unfortunately, it needs to be set when the instance is created.

JakenVeina•14mo ago

why?

Will PittengerOP•14mo ago

I want it public readonly.

JakenVeina•14mo ago

ergo, it doesn't need to be

Will PittengerOP•14mo ago

It isn't valid without it.

JakenVeina•14mo ago

for one, it shouldn't be a field for two, initialzing it after construction doesn't make it not valid so long as you don't publish the instance for consumption before initialization is complete

public class Y
{
    public static Y ParseFromJson(string json)
    {
        var y = new Y()
        {
            Items = JsonConverter.Deserialize<List<object>>(sourceJson);
        };

        foreach(var item in items)
            if (item is X x)
                x.Owner = y;

        return y;
    }

    private Y() {}

    public required IReadOnlyList<object> Items { get; init; }
}

public class X
{
    internal X() {}

    public Y Owner { get; internal set; }
        = null!;

    public required string Wrapped {get; init;}

    public required string SomeOtherValue{get; init;}
}

public class Y
{
    public static Y ParseFromJson(string json)
    {
        var y = new Y()
        {
            Items = JsonConverter.Deserialize<List<object>>(sourceJson);
        };

        foreach(var item in items)
            if (item is X x)
                x.Owner = y;

        return y;
    }

    private Y() {}

    public required IReadOnlyList<object> Items { get; init; }
}

public class X
{
    internal X() {}

    public Y Owner { get; internal set; }
        = null!;

    public required string Wrapped {get; init;}

    public required string SomeOtherValue{get; init;}
}

TheRanger•14mo ago

well, would public Y Owner { get; private set; } be fine with you?

Will PittengerOP•14mo ago

Somewhat. What about the init accessor for the owner?

TheRanger•14mo ago

well i found a weird way,

public class Y
{
    public System.Collections.Generic.List<X> list = new();
    public static Y LatestInstance {get; private set;}

    public static Y Deserialize(string json)
    {
        return new Y()
        {
            list = JsonConvert.DeserializeObject<System.Collections.Generic.List<X>>(json),
        };
    }

    public Y()
    {
        LatestInstance = this;
    }
}

public class X
{
    public required Y Owner {get; init;}
    [JsonProperty("wrapped")]
    public required string Wrapped { get; init; }

    [JsonProperty("some other value")]
    public required string SomeOtherValue {  get; init; }

    public static explicit operator X(string str) => Parse(str);

    public static X Parse(string str)
    {
        return new X
        {
            Wrapped = str,
            Owner = Y.LatestInstance,
            SomeOtherValue = "default",
        };
    } 

    public X()
    {
        Owner = Y.LatestInstance;
    }
}

public class Y
{
    public System.Collections.Generic.List<X> list = new();
    public static Y LatestInstance {get; private set;}

    public static Y Deserialize(string json)
    {
        return new Y()
        {
            list = JsonConvert.DeserializeObject<System.Collections.Generic.List<X>>(json),
        };
    }

    public Y()
    {
        LatestInstance = this;
    }
}

public class X
{
    public required Y Owner {get; init;}
    [JsonProperty("wrapped")]
    public required string Wrapped { get; init; }

    [JsonProperty("some other value")]
    public required string SomeOtherValue {  get; init; }

    public static explicit operator X(string str) => Parse(str);

    public static X Parse(string str)
    {
        return new X
        {
            Wrapped = str,
            Owner = Y.LatestInstance,
            SomeOtherValue = "default",
        };
    } 

    public X()
    {
        Owner = Y.LatestInstance;
    }
}

its probably dumb, but probably only the way with the required attribute

Will PittengerOP•14mo ago

BTW: Your X doesn't declare owner. Oh it does. I was expecting a [JsonIgnore] on it as the owner isn't in the JSON.

TheRanger•14mo ago

ur json doesnt have a Owner field so it will be null as default you can put [JsonIgnore] in case

Will PittengerOP•14mo ago

Unfortunately, all instances need to have an valid owner--even if the full version of the class was used.

TheRanger•14mo ago

what do u mean? isn't the owner valid in your json?

Will PittengerOP•14mo ago

Go back to the original short form mentioned in https://discord.com/channels/143867839282020352/1157109068423507988/1157150777404571708. The first value in the array would end up with an owner using your code. But not the second. Both must have owners. (In this case, the same owner.)

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TheRanger•14mo ago

ah so u have 2 forms of that in the same json?

Will PittengerOP•14mo ago

Yes.

TheRanger•14mo ago

in the same list/array?

Will PittengerOP•14mo ago

Yes. Only the full form will ever be written. But the short form might be on the website as a way of specifying predefined entries.

TheRanger•14mo ago

i tested this

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  },
  {
    "t": 
    {
      "wrapped": "ss",
      "some other value": "default"
    }
  },
  {
    "t":
    {
      "wrapped": "value",
      "some other value": "value2"
    }
  }
]

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  },
  {
    "t": 
    {
      "wrapped": "ss",
      "some other value": "default"
    }
  },
  {
    "t":
    {
      "wrapped": "value",
      "some other value": "value2"
    }
  }
]

all have the same owner but how do you think the last 2 elements in the array would be converted with this code

Will PittengerOP•14mo ago

No.

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

[
  "ss",
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

Those are both elements in the array. That's equivalent to:

[
  {
    "wrapped": "ss",
    "some other value": "default"
  },
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

[
  {
    "wrapped": "ss",
    "some other value": "default"
  },
  {
    "wrapped": "value",
    "some other value": "value2"
  }
]

TheRanger•14mo ago

so u dont have something like this in ur json anymore?

    "t":
    {
      "wrapped": "value",
      "some other value": "value2"
    }

    "t":
    {
      "wrapped": "value",
      "some other value": "value2"
    }

Will PittengerOP•14mo ago

I think that was a mistake in the other class.

TheRanger•14mo ago

then what original short form were u talking about

Will PittengerOP•14mo ago

TheRanger•14mo ago

Yes, that is what i used both have same owner

Will PittengerOP•14mo ago

So you didn't do anything special?

TheRanger•14mo ago

did you use this code?

Will PittengerOP•14mo ago

Didn't try it yet. Been busy elsewhere while waiting on the other issues. Got started on those.

TheRanger•14mo ago

🤷🏻‍♂️

Will PittengerOP•14mo ago

Sorry. I also still on the fence if your solution is acceptable. It does have a bit of code smell.

TheRanger•14mo ago

well, i tested it, so it works fine for me

Will PittengerOP•14mo ago

OK.

Accord•14mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ NewtownSoft.JSON and classes that need references to its owner