Creating an instance of an unknown object send an invalid Create operation about leshan

[sophokles73]

So far, so good. I guess you wouldn't have created the issue if you were content with what you observe ;-) Could you give us a hint what you think should be different?

[dnav]

Well the payload must contain the content of the new instance if I understand the LWM2M TS correctly.

The “Create” operation has the following parameters:

Parameter	Required	Default Value	Notes
Object ID	Yes	-	Indicates the Object.
New Value	Yes	-	The new value included in the payload to create the Object Instance(s)

Table 14: Create parameters
The new value included in the payload MUST follow the TLV or JSON format according to the Content-Format option which MUST be specified.

For objects which model are known by Leshan, the Leshan UI asks for the cotent of the new instance.

[sophokles73]

Okay, so we are talking about the demo server's UI. I think that the demo server can dynamically create a form for entering the payload if it is provided with a json file describing the object type at startup. However, I am not very much involved in the demo server UI so we'll have to defer this question to our friends from Sierra Wireless.

@msangoi, @sbernard31 any idea?

[dnav]

Yes sorry. I forgot to specify I used the server deployed at leshan.eclipse.org
The demo server's UI indeed provide a form when the object layout is known.

Easiest fix would be to disable the "Create New Instance" when the object layout is unknown.

[sbernard31]

I rethink about this point.
If leshan doesn't know the model and there is no instance, it just show the create button.
In this case you can try to create an instance with no payload as we don't know anything about the model.
If there is no mandatory resource you should be able to create it then read the instance. If there is mandatory resource this will fail but we can not do better.

So I think it's ok like this.
Anyway the right solution is to add the corresponding model using --modelsfolder option.

[sbernard31]

I created a PR #805 which make clearer that Leshan does not know a model :