ReactJS array of arrays state - reactjs

Question

I'd like to assign an array of arrays in a state.
I found a few elements about modifying an array of arrays, this is not what I want to do.
I'm first building the array of arrays (which won't change beyond construction) then try to set the state, but it stays empty ([]).
Here is the solidity part :
contract Test {
struct Bobject {
address owner;
uint amount;
}
struct Dobject {
uint id;
uint ddate;
string label;
uint quantity;
mapping(uint => Bobject) bobjs;
uint bCount;
}
uint public dCount = 0;
mapping(uint => Dobject) public dobjs;
function getBobj( uint did, uint bid) external view returns(Bobject memory) {
return dobjs[did].bobjs[bid];
}
}
And the react JS useEffect code I'm testing now, the "barray" contains the array of arrays of Bojects, no problem, but after setBobjs( bobjs => barray); bobjs is still [].
const [dobjs, setDobjs] = useState([]);
const [bobjs, setBobjs] = useState([]);
useEffect(() => {
setDobjs( dobjs => []);
setBobjs( bobjs => []);
const dCount = await contract.dCount();
const barray = Array();
for (let i = 1; i <= dCount; i++) {
const dobj = await contract.dobjects(i);
setDobjs(dobjs => [...dobjs, dobj]);
const bCount = dobj.bCount;
const sbarray = Array();
for( let j=1; j <= bCount; j++) {
let nobj = await contract.getBobj(i, j);
sbarray.push( nobj);
}
barray.push( sbarray);
}
setBobjs(bobjs => barray);
}
I came accross another consideration that is not 100% clear to me even after spending the full day in forums :
I chose to query the contract for the Bobjects and implemented a custom getter because the Dobjects I get with contract.dobjects(i); do not contain the "bobjs" mapping member
Maybe there is a better way to get the Bobjects ?
Anyway, any help is appreciated, I have to take a break ;)
Thanks !