Unable to deserialize ArraySegment<int> with System.Text.Json.JsonSerializer.Deserialize

[isukces]

Description

Unable to deserialize ArraySegment<int> using System.Text.Json.JsonSerializer, even when the value was serialized using System.Text.Json.JsonSerializer.

Reproduction Steps

Use XUnit test below:

[Fact]
public void Should_serialize_with_system_text_json()
{
    int[] src          = [1, 2, 3];
    var   arraySegment = new ArraySegment<int>(src);
    var   json         = System.Text.Json.JsonSerializer.Serialize(arraySegment);
    _testOutputHelper.WriteLine(json);
    var obj = System.Text.Json.JsonSerializer.Deserialize<ArraySegment<int>>(json);
    Assert.Equal(3, obj.Count);
}

Expected behavior

The System.Text.Json.JsonSerializer should be able to successfully deserialize an ArraySegment<int> object that was serialized using the same or other serializer, without any errors or data loss.

Actual behavior

When attempting to deserialize an ArraySegment<int> object using System.Text.Json.JsonSerializer, a NotSupportedException is thrown, indicating that deserialization is not supported for this type, despite it being serialized with the same serializer.

Regression?

No response

Known Workarounds

As a workaround, you can use Newtonsoft.Json.JsonConvert for both serialization and deserialization of ArraySegment<int>. JsonConvert handles this type without throwing exceptions, providing a seamless serialization/deserialization process.

Configuration

Other information

No response

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[huoyaoyuan]

It wasn't supported for deserialization. The criteria for serializing and deserializing are different. Serializing requires read access only while deserializing requires way to construct the type.
For ArraySegment<T>, it's serializable because it implements IList<T>, but it isn't deserializable because it doesn't implement the common shape for constructable collections. It's not supported by other features like collection expressions in C# either.
Make it deserializable is a feature request that requires explicit recognition of this type.

[eiriktsarpalis]

The type doesn't implement one of the standard construction patterns (default constructor with Add method, constructor accepting IEnumerable<T> or CollectionBuilderAttribute annotation). There's a proposal that we add CollectionBuilderAttribute support to STJ tracked by #82642, at which point adding CollectionBuilderAttribute to ArraySegment` would automatically give support to the type.