[Question] Is it possible to serialize alphabetically?

[TMaddox]

I want to serialize alphabetically, including the discriminator, is this possible?

My class: (note I called my discriminator: "serializer")

    [CborDiscriminator("atom" , Policy = CborDiscriminatorPolicy.Always)]
    public class Atom
    {
        public int Z  { get; set; }
        public int A  { get; set; }
    }

This should serialize to:
{"A": 10, "serializer": "atom", "Z": 10}

Is this possible?

Edit: I need this because I need the hash of the cbor byte[] to match implementations in other languages

[mcatanzariti]

Hi,

It would be possible to sort the member mappings during the object mapping initialization just after having call AutoMap.

However, in the current implementation, the discriminator is not materialized as an member mapping but is always serialized as the first property into the Cbor object...

[TMaddox]

Any idea how I can archive this? I would really need this to calculate the correct hash.

[jonassix]

Hi mcatanzariti,

Could you guide us in the right direction? Look at this example.

               {
                  "particle":{
                     "bytes":h                     '015757CDD6C17B409113E2979D58F611832103D0E2ACE56D2F8E15AAA285C57BBA9C0184D54CDD781B5637675704B5D1EA2BD800000010CCF4BD45FA4E2CDA8673BD45BF721878C05D57102856663EDA2160BF0B2FD83BF7A2B6D1ED6093B1CF769AFDD5EA1688',
                     "destinations":[
                        h                        '0217D072D6C4BC39D778FABC352ABBC3B4',
                        h                        '027BE4CA91F62F11794CCF66A92B771406'
                     ],
                     "from":h                     '040202385C29EF952488C05C6E44563CB73CBB163BEE9136E4366EF5AF2560B8CA05BE5F1F84C0',
                     "metaData":{
                        "application":"message"
                     },
                     "nonce":5275583715703691872,
                     "serializer":"radix.particles.message",
                     "to":h                     '0402023B2DC2EAA3A237C9AB13E3EC0357679DB51EFB63A7DC95980AD81A90D9B0EBD30C695A1B',
                     "version":100
                  },
                  "serializer":"radix.spun_particle",
                  "spin":1,
                  "version":100
               }

This is a payload we need to be able to generate and then create a hash of it. As a consequence correct sequence of properties is really important for us.
As you can see here, the properties are sorted alphabetically. Including the discriminator which is the property "serializer".

Any idea how we can achive this?

[TMaddox]

Could you please let us know if you are going to implement this or not and if you are going to, can you give us an ETA?

[mcatanzariti]

Hi Maddox,

I have no simple solution right now.
The discriminator is not an actual property. It's added on the spot as the first property when the framework detect a polymorphic object.

A bad and slow workaround could be to serialize your class in a temporary cbor buffer. Then to deserialize it into a CborObject. Then sort the CborObject properties and serialize it again in the destination Cbor buffer

[TMaddox]

This would only work if I haven't got nested objects, wouldn't it? Only the top-level object would be sorted?

[mcatanzariti]

You would have to recursively sort CborObject within CborObject

[TMaddox]

I tried that, but for example a CborValueType.Array doesn't have any public properties exposing the value, so I can't sort it. Any suggestions?

Edit: After further investigation, I think that the only types which I am able to sort recursively are CborValueType.Object. All others don't expose the value publicly (right now, I think the only one I would need to expose it is CborValueType.Array, as it holds other CborValueType.Object in my case)

[mcatanzariti]

If the type is array, you can cast it to CborArray and iterate directly this class.

[TMaddox]

I managed to sort it now, I'll leave this issue open and hope you will implement it, because the solution right now is, as you said, a bad and slow workaround.

Thanks for the help!

[mcatanzariti]

Release 1.6.0 brings the possibility to sort a type members alphabetically including the type discriminator.

Beware of several breaking changes listed in 1.6.0 release notes

    public class Issue0046
    {
        [CborDiscriminator("atom", Policy = CborDiscriminatorPolicy.Always)]
        public class Atom
        {
            public int Z { get; set; }
            public int A { get; set; }
        }

        [Fact]
        public void Test()
        {
            CborOptions options = new CborOptions();
            options.Registry.DiscriminatorConventionRegistry.RegisterConvention(new AttributeBasedDiscriminatorConvention<string>(options.Registry, "serializer"));
            options.Registry.ObjectMappingRegistry.Register<Atom>(objectMapping =>
            {
                objectMapping.AutoMap();
                objectMapping.SetOrderBy(m => m.MemberName);
            });

            Atom obj = new Atom
            {
                A = 10,
                Z = 10
            };

            const string hexBuffer = "A361410A6A73657269616C697A65726461746F6D615A0A";
            Helper.TestWrite(obj, hexBuffer, null, options);
        }
    }