strange Constructor behavior under last version

[vsfeedback]

This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work] [regression] [worked-in:17.3.0 preview 2] String json = someTextData ProgramSettings? tmpProgramSettings = new ProgramSettings(someText_Required);

The following line is trigerring the ProgramSettings Constructor tmpProgramSettings = JsonConvert.DeserializeObject(json);

but it's calling the constructor with an EMPTY required parameter Wich is not only odd but also crash my program.

To avoid it, I have to Create a parameterless constructor.

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Original Comments

Tracy Wang [MSFT] on 7/10/2022, 08:18 PM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:14 AM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:48 AM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:59 AM:

(private comment, text removed)

Feedback Bot on 7/11/2022, 05:30 PM:

(private comment, text removed)

Cassie Li [MSFT] on 7/11/2022, 07:15 PM:

(private comment, text removed)

Feedback Bot on 7/11/2022, 07:54 PM:

(private comment, text removed)

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Original Solutions

(no solutions)

[dotnet-issue-labeler[bot]]

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[msftbot[bot]]

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Issue Details

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This issue has been moved from a ticket on Developer Community.

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[severity:It's more difficult to complete my work] [regression] [worked-in:17.3.0 preview 2] String json = someTextData ProgramSettings? tmpProgramSettings = new ProgramSettings(someText_Required);

The following line is trigerring the ProgramSettings Constructor tmpProgramSettings = JsonConvert.DeserializeObject(json);

but it's calling the constructor with an EMPTY required parameter Wich is not only odd but also crash my program.

To avoid it, I have to Create a parameterless constructor.

---

Original Comments

Tracy Wang [MSFT] on 7/10/2022, 08:18 PM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:14 AM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:48 AM:

(private comment, text removed)

Patrice Charbonneau on 7/11/2022, 06:59 AM:

(private comment, text removed)

Feedback Bot on 7/11/2022, 05:30 PM:

(private comment, text removed)

Cassie Li [MSFT] on 7/11/2022, 07:15 PM:

(private comment, text removed)

Feedback Bot on 7/11/2022, 07:54 PM:

(private comment, text removed)

---

Original Solutions

(no solutions)

Author:	vsfeedback
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[eiriktsarpalis]

Would it be possible to share a minimal reproduction as well a stacktrace of the error you are experiencing? It looks like you are using Json.NET, I would recommend opening an issue in that project.

[msftbot[bot]]

This issue has been marked needs-author-action and may be missing some important information.

[ghost]

Hi,

I have submitted to Microsoft full demo project to reproduce it. let me find it back I'll post it here

[ghost]

Here the demo example, I got rid of Newtonsoft to show it's a .NET bug and not NewtonSoft https://lebudget.com/download/BugConstructor2022-07-11.zip

[eiriktsarpalis]

I've extracted the following minimal reproduction from the code sample:

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

string json = "{  \"dicSettings\": {  }}";

//put a break point here and Debug Follow next line
//The Next line Called the ProgramSettings constructor with no parameter.  This is NOT supposed to happen
//JsonConvert.DeserializeObject<ProgramSettings>(json);
JsonSerializer.Deserialize<ProgramSettings>(json);

public class ProgramSettings
{
    public Dictionary<String, String> dicSettings = new Dictionary<String, String>();

    //public ProgramSettings()
    //{
    //    //If you uncomment this, it fix it, but it make no sense that the constructor is called
    //}

    public ProgramSettings(String pstrNewValue)
    {
        dicSettings.Add(pstrNewValue, "Ok");
    }
}

The code fails with the following exception:

System.InvalidOperationException: Each parameter in the deserialization constructor on type 'ProgramSettings' must bind to an object property or field on deserialization. Each parameter name must match with a property or field on the object. Fields are only considered when 'JsonSerializerOptions.IncludeFields' is enabled. The match can be case-insensitive.
   at System.Text.Json.ThrowHelper.ThrowInvalidOperationException_ConstructorParameterIncompleteBinding(Type parentType)
   at System.Text.Json.Serialization.Converters.ObjectWithParameterizedConstructorConverter`1.OnTryRead(Utf8JsonReader& reader, Type typeToConvert, JsonSerializerOptions options, ReadStack& state, T& value)

However, this is by-design behavior. The serializer (either Json.NET or System.Text.Json) must bind to a constructor in order to be able to deserialize the type. See this article for more details on constructors are used in the context of deserialization.