dahomey-technologies/Dahomey.Cbor

How-to do a Custom ArrayConverter

kirstadt opened this issue · 2 comments

kirstadt commented

Hi Michaël,

trying some days to get my head around a problem, but I'm pretty much stuck by now.

There are the following json/cbor objects.

{ "value": 0.567 }

{ "value": -110 }

{ "value": "Bar" }

For the first three I found a solution using an extended CborConverterBase<>.

public class DynamicTypeConverter : CborConverterBase<DynamicValue>
    {
        public override DynamicValue Read(ref CborReader reader)
        {
            CborDataItemType type = reader.GetCurrentDataItemType();

            if (type == CborDataItemType.Unsigned) return new DynamicValue() { value = reader.ReadDouble() };
            if (type == CborDataItemType.Signed) return new DynamicValue() { value = reader.ReadDouble() };
            if (type == CborDataItemType.Double) return new DynamicValue() { value = reader.ReadDouble() };
            if (type == CborDataItemType.String) return new DynamicValue() { valueString = reader.ReadString() };

But I can't get the following one to work.

{ "value":[{"Name":"Beer","Temperature":3,"Count":33},{"Name":"Wine","Temperature":7,"Count":6}]}

I tried adding a new condition and a class holding the three values.

	if (type == CborDataItemType.Array)
	{
		DynamicValue dynamicValue = new DynamicValue();
		BarContent context = new BarContent();

		int size = reader.ReadSize();
		this.ReadBeginArray(size, context);

		reader.ReadBeginArray(size, ref context);

		while (size > 0 || size < 0 && GetCurrentDataItemType() != CborDataItemType.Break)
		{
			arrayReader.ReadArrayItem(ref this, ref context);
			size--;
		}
                
                dynamicValue.BarContent = context;
		return dynamicValue;
	}

But this doesn't compile. I don't understand the whole context stuff and how to use it properly.

Is this even the right approach doing it in a converter?

Can you please give me some hints how to solve my problem?

Thanks! :-)

rmja commented

Hi,

Can you show some details about the C# model that you use for:

{ "value":[{"Name":"Beer","Temperature":3,"Count":33},{"Name":"Wine","Temperature":7,"Count":6}]}

Having a model like this should just work:

public class MultipleValues
{
    public List<DynamicValue> Value { get; set; }
}

That is, you do not need to make a converter for the "list or array" - only for the item type in the array.