JsonSerializer.Deserialize<T>() not work

[GF-Huang]

Description

The JsonSerializer.Deserialize<T> not fill properties of Settings.

JSON file content:

Code:

public record ApiConfig {
    public string AppUrl { get; init; } = string.Empty;

    public string AuthenticationEndPoint { get; init; } = string.Empty;

    public string TokenEndPoint { get; init; } = string.Empty;

    public string AppKey { get; init; } = string.Empty;

    public string OpenApiBaseUrl { get; init; } = string.Empty;

    public string StreamingUrl { get; set; } = string.Empty;
}

public class Settings {
    public ApiConfig OpenApiConfig { get; } = new();
}

var text = ... // json content as above
// Why settings all properties are empty?
var settings = JsonSerializer.Deserialize<Settings>(text) ?? throw new InvalidDataException(...);

Reproduction Steps

As my code.

Expected behavior

The settings returned by JsonSerializer.Deserialize<T> be filled.

Actual behavior

The settings properties all keep empty.

Regression?

No response

Known Workarounds

No response

Configuration

.NET: 7.0.2
OS: 10.0.22621.0

Other information

No response

[ghost]

Tagging subscribers to this area: @dotnet/area-system-text-json, @gregsdennis
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Description

The JsonSerializer.Deserialize<T> not fill properties of Settings.

JSON file content:

Code:

public record ApiConfig {
    public string AppUrl { get; init; } = string.Empty;

    public string AuthenticationEndPoint { get; init; } = string.Empty;

    public string TokenEndPoint { get; init; } = string.Empty;

    public string AppKey { get; init; } = string.Empty;

    public string OpenApiBaseUrl { get; init; } = string.Empty;

    public string StreamingUrl { get; set; } = string.Empty;
}

public class Settings {
    public ApiConfig OpenApiConfig { get; } = new();
}

var text = ... // json content as above
// Why settings all properties are empty?
var settings = JsonSerializer.Deserialize<Settings>(text) ?? throw new InvalidDataException(...);

Reproduction Steps

As my code.

Expected behavior

The settings returned by JsonSerializer.Deserialize<T> be filled.

Actual behavior

The settings properties all keep empty.

Regression?

No response

Known Workarounds

No response

Configuration

.NET: 7.0.2
OS: 10.0.22621.0

Other information

No response

Author:	GF-Huang
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[Clockwork-Muse]

... If these settings are for your own application, there are existing libraries for binding configuration.

That said, this is because Settings.OpenApiConfig is get only. If you change it to at least init it will work:

public class Settings {
    public ApiConfig OpenApiConfig { get; init; } = new();
}

[GF-Huang]

God, there is still a gap between Systen.Text.Json and Newtonsoft.Json even in .NET 7.

[eiriktsarpalis]

This is because System.Text.Json doesn't support populate behavior yet, but we're working on it.

Duplicate of #78556.

cc @krwq