System.Text.Json: Sort by key Hashtable?

Question

I am serializing my object using a simple:

var options = new JsonSerializerOptions { WriteIndented = true, IncludeFields = true};
string jsonString = JsonSerializer.Serialize(obj, options);
File.WriteAllText("output.json", jsonString);

However my hierarchy contains a Hashtable. I'd like to have the Hashtable content be written in a consistent manner: always order by Keys (key is string in my case).

How can I do that in .NET 5 ?

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My question is about Hashtable content and is no way related to ordering of class fields.

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I cannot simply change the type of Hashtable to SortedDictionary since this would break all my existing BinaryFormatter serialized streams.

Answer 1

You could use a property as a pass-through:

    [JsonIgnore]
    public Hashtable MyHashtable { get; set; }
    
    [JsonPropertyName("MyHashtable")]
    public SortedDictionary<string, string> MyHashtableSorted 
    {
        get => new SortedDictionary<string, string>(
                     MyHashtable
                     .Cast<DictionaryEntry>()
                     .ToDictionary(x => (string)x.Key, x => (string)x.Value)
                );
        set {
            MyHashtable = new Hashtable();
            foreach (var x in value)
                MyHashtable.Add(x.Key, x.Value);
        }
    }

Or just use a SortedDictionary as your property type to start with...