JLD2 type compatibility

I am using JLD2 to store some data in struct format, it works great. However some of the objects need to change, as I need to add more members.
e.g.

struct A
    n::Int
    a::String
end

might become

struct A
    n::Int
    a::String
    b::String
end

when I read an old object with the new code it gives me this warning:

┌ Warning: saved type A is missing field b in workspace type; reconstructing 
└ @ JLD2 C:\.julia\packages\JLD2\k9Gt0\src\data\reconstructing_datatypes.jl:152

this is fine, the behavior is described here:

However I am not sure how the proposed type remapping with typemap could help me: I would like to be able to load the old object in the new format but providing a default for eventual new properties.
I remember with JLD I was used to leverage on features like JLD.readas and JLD.translate, is there anything similar with JLD2?

Hi @Alessio_Bellisomi ,

you will have to do the conversion yourself after loading the dataset into the old struct as described in the docs.

Ok, I understand. Let’s assume I have a mix of files, some built in the old structure and some in the new one. Is there a way I can tell if the one I am loading needs conversion at runtime? thanks