System.Text.Json IgnoreReadOnlyProperties not working for enumerables

[npp127]

Description

Given a class

    public class Test
    {
        public int MyProperty1 { get; set; } = 69;

        public int MyProperty2 { get; } = 420;

        public IEnumerable<int> Collection1 { get; set; } = new int[] { 69, 420 };

        public IEnumerable<int> Collection2 { get; } = new int[] { 69, 420 };
    };

by setting IgnoreReadOnlyProperties to true, one would expect that only "MyProperty1" and "Collection1" would be serialized.
Collection2 Gets also serialized for whatever reason.

Reproduction Steps

Test class

namespace T
{
    public class Test
    {
        public int MyProperty1 { get; set; } = 69;
        public int MyProperty2 { get; } = 420;

        public IEnumerable<int> Collection1 { get; set; } = new int[] { 69, 420 };

        public IEnumerable<int> Collection2 { get; } = new int[] { 69, 420 };
    };
}

Program.cs

using System.Text.Json;
using T;

var opt = new JsonSerializerOptions()
{
    IgnoreReadOnlyProperties = true,
    WriteIndented = true,
};


var obj = new Test();

var json =  JsonSerializer.Serialize(obj, opt);

Console.WriteLine(json);

Csproj

<Project Sdk="Microsoft.NET.Sdk">
	<PropertyGroup>
		<OutputType>Exe</OutputType>
		<TargetFramework>net7.0</TargetFramework>
		<ImplicitUsings>enable</ImplicitUsings>
		<Nullable>enable</Nullable>
		<LangVersion>latest</LangVersion>
	</PropertyGroup>
</Project>

Expected behavior

{
  "MyProperty1": 69,
  "Collection1": [
    69,
    420
  ]
}

Actual behavior

{
  "MyProperty1": 69,
  "Collection1": [
    69,
    420
  ],
  "Collection2": [
    69,
    420
  ]
}

Regression?

No response

Known Workarounds

No response

Configuration

No response

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

Given a class

    public class Test
    {
        public int MyProperty1 { get; set; } = 69;

        public int MyProperty2 { get; } = 420;

        public IEnumerable<int> Collection1 { get; set; } = new int[] { 69, 420 };

        public IEnumerable<int> Collection2 { get; } = new int[] { 69, 420 };
    };

by setting IgnoreReadOnlyProperties to true, one would expect that only "MyProperty1" and "Collection1" would be serialized.
Collection2 Gets also serialized for whatever reason.

Reproduction Steps

Test class

namespace T
{
    public class Test
    {
        public int MyProperty1 { get; set; } = 69;
        public int MyProperty2 { get; } = 420;

        public IEnumerable<int> Collection1 { get; set; } = new int[] { 69, 420 };

        public IEnumerable<int> Collection2 { get; } = new int[] { 69, 420 };
    };
}

Program.cs

using System.Text.Json;
using T;

var opt = new JsonSerializerOptions()
{
    IgnoreReadOnlyProperties = true,
    WriteIndented = true,
};


var obj = new Test();

var json =  JsonSerializer.Serialize(obj, opt);

Console.WriteLine(json);

Expected behavior

{
  "MyProperty1": 69,
  "Collection1": [
    69,
    420
  ]
}

Actual behavior

{
  "MyProperty1": 69,
  "Collection1": [
    69,
    420
  ],
  "Collection2": [
    69,
    420
  ]
}

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	npp127
Assignees:	-
Labels:	area-System.Text.Json
Milestone:	-

[npp127]

it's like that by design for enumerables and dictionaries

runtime/src/libraries/System.Text.Json/src/System/Text/Json/Serialization/Metadata/JsonPropertyInfo.cs

Lines 425 to 441 in d783bad

	if ((EffectiveConverter.ConverterStrategy & (ConverterStrategy.Enumerable | ConverterStrategy.Dictionary)) != 0)
	{
	// Properties of collections types that only have setters are not supported.
	if (Get == null && Set != null && !_isUserSpecifiedSetter)
	{
	CanDeserialize = false;
	}
	}
	else
	{
	// For read-only properties of non-collection types, apply IgnoreReadOnlyProperties/Fields policy,
	// unless a `ShouldSerialize` predicate has been explicitly applied by the user (null or non-null).
	if (Get != null && Set == null && IgnoreReadOnlyMember && !_isUserSpecifiedShouldSerialize)
	{
	CanSerialize = false;
	}
	}

Properties of collections types that only have setters are not supported.

But should they?

I'm missing whats the point of the reasoning for not supporting that.
Something like .IgnoreReadOnlyEnumerables with false as a default would allow users to avoid this behaviour

[krwq]

I'm marking this as 8.0 for now because we should define behavior for this in #78556 and they should be looked at hollistically

[eiriktsarpalis]

Duplicate of #67514 and #37599. IIUC this is intentional behavior and collections are treated specially w.r.t. this flag. Changing this now would be a breaking change. We might consider solving this using a different flag that supersedes IgnoreReadOnlyProperties.

[npp127]

Duplicate of #67514 and #37599. IIUC this is intentional behavior and collections are treated specially w.r.t. this flag. Changing this now would be a breaking change. We might consider solving this using a different flag that supersedes IgnoreReadOnlyProperties.

Shouldn't this behaviour be made configurable from the options?

[eiriktsarpalis]

Moving to Future.

[wiz0u]

Same for getter-only arrays. They get serialized, even though they are obviously not deserializable (can't set or resize the array)

My test program:

using System.Text.Json;
 
var test = new Test();
Console.WriteLine(JsonSerializer.Serialize(test, new JsonSerializerOptions { IgnoreReadOnlyProperties = true }));

public partial class Test
{
	public int Id => 123;
	public int[] SomeArrayProp => new[] { 456 };
	public IEnumerable<int> SomeIEnumProp { get { yield return 789; } }
}