Unable to deserialize ienumerables that is not a list

[musictopia2]

Description

If I have a custom list like this

public class SecondList<T> : IEnumerable<T>
{
    protected List<T> PrivateList = new();
    public SecondList()
    {

    }
    protected bool IsStart = true;
    public void Add(T item)
    {
        PrivateList.Add(item);
    }
    public IEnumerator<T> GetEnumerator()
    {
        return PrivateList.GetEnumerator();
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return PrivateList.GetEnumerator();
    }
}

then when i try to deserialize it, then it gives me a runtime error saying "The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'"

that is obviously incorrect though.

I am able to deserialize no problem with newtonsofts. I need to transfer to system.json for better performance.
Is there any way to make it work with custom classes that implement ienumerable that behind the scenes use the standard list?

Reproduction Steps

in a global class, use something like this
global using jj = System.Text.Json;

then in main, use code like this

SecondList list = new()
{
1,
2,
3,
4
};

text = jj.JsonSerializer.Serialize(list);
Console.WriteLine(text);

SecondList? list2 = jj.JsonSerializer.Deserialize<SecondList>(text);
foreach (var item in list2!)
{
Console.WriteLine(item);
}

Expected behavior

The second set of code shows the deserialized and the proper numbers print.

Actual behavior

The runtime error with this message
The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'

There needs to be a way to deserialize even custom classes that implement ienumerable like newtonsoft has.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

[ghost]

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

Issue Details

---

Description

If I have a custom list like this
public class SecondList : IEnumerable
{
protected List PrivateList = new();
public SecondList()
{

}
protected bool IsStart = true;
public void Add(T item)
{
    PrivateList.Add(item);
}
public IEnumerator<T> GetEnumerator()
{
    return PrivateList.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
    return PrivateList.GetEnumerator();
}

}

then when i try to deserialize it, then it gives me a runtime error saying "The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'"

that is obviously incorrect though.

I am able to deserialize no problem with newtonsofts. I need to transfer to system.json for better performance.
Is there any way to make it work with custom classes that implement ienumerable that behind the scenes use the standard list?

Reproduction Steps

in a global class, use something like this
global using jj = System.Text.Json;

then in main, use code like this

SecondList list = new()
{
1,
2,
3,
4
};

text = jj.JsonSerializer.Serialize(list);
Console.WriteLine(text);

SecondList? list2 = jj.JsonSerializer.Deserialize<SecondList>(text);
foreach (var item in list2!)
{
Console.WriteLine(item);
}

Expected behavior

The second set of code shows the deserialized and the proper numbers print.

Actual behavior

The runtime error with this message
The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'

There needs to be a way to deserialize even custom classes that implement ienumerable like newtonsoft has.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	musictopia2
Assignees:	-
Labels:	area-System.Linq, untriaged
Milestone:	-

[ghost]

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

Issue Details

---

Description

If I have a custom list like this
public class SecondList : IEnumerable
{
protected List PrivateList = new();
public SecondList()
{

}
protected bool IsStart = true;
public void Add(T item)
{
    PrivateList.Add(item);
}
public IEnumerator<T> GetEnumerator()
{
    return PrivateList.GetEnumerator();
}
IEnumerator IEnumerable.GetEnumerator()
{
    return PrivateList.GetEnumerator();
}

}

then when i try to deserialize it, then it gives me a runtime error saying "The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'"

that is obviously incorrect though.

I am able to deserialize no problem with newtonsofts. I need to transfer to system.json for better performance.
Is there any way to make it work with custom classes that implement ienumerable that behind the scenes use the standard list?

Reproduction Steps

in a global class, use something like this
global using jj = System.Text.Json;

then in main, use code like this

SecondList list = new()
{
1,
2,
3,
4
};

text = jj.JsonSerializer.Serialize(list);
Console.WriteLine(text);

SecondList? list2 = jj.JsonSerializer.Deserialize<SecondList>(text);
foreach (var item in list2!)
{
Console.WriteLine(item);
}

Expected behavior

The second set of code shows the deserialized and the proper numbers print.

Actual behavior

The runtime error with this message
The collection type 'RethinkList.SecondList`1[System.Int32]' is abstract, an interface, or is read only, and could not be instantiated and populated. Path: $ | LineNumber: 0 | BytePositionInLine: 1.'

There needs to be a way to deserialize even custom classes that implement ienumerable like newtonsoft has.

Regression?

No response

Known Workarounds

No response

Configuration

No response

Other information

No response

Author:	musictopia2
Assignees:	-
Labels:	area-System.Text.Json, untriaged
Milestone:	-

[eiriktsarpalis]

Duplicate of #38514. One workaround is to implement a custom converter for your collection.