How to make component item change owner automatically with its parent? - api

Question

I'm learning hyperledger composer and I don't know how to modify chaincode to make following model work:
This is my cto:
asset Item identified by itemId{
o String itemId
o String name
o String idgId
o String serialNumber
o String comment
--> BU owner
--> Item [] items optional
}
abstract participant BU identified by buId{
o String buId
o String name
o String country
o String city
}
participant Manufacturer extends BU{
}
participant Assembler extends BU{
}
And chaincode:
function tradeCommodity(trade) {
trade.item.owner = trade.newOwner;
return getAssetRegistry('org.dps.track.Item')
.then(function (assetRegistry) {
var tradeNotification = getFactory().newEvent('org.dps.track', 'TradeNotification');
tradeNotification.item = trade.item;
emit(tradeNotification);
// persist the state of the commodity
return assetRegistry.update(trade.item);
});
}
then i make two items: I1 and I2 - which will be components of third item I3
like this:
{
"$class": "org.dps.track.Item",
"itemId": "I1",
"name": "c1",
"idgId": "123",
"serialNumber": "123",
"comment": "component1",
"owner": "resource:org.dps.track.Assembler#BU2"
},
{
"$class": "org.dps.track.Item",
"itemId": "I2",
"name": "c2",
"idgId": "456",
"serialNumber": "456",
"comment": "component2",
"owner": "resource:org.dps.track.Assembler#BU2"
},
{
"$class": "org.dps.track.Item",
"itemId": "I3",
"name": "complex",
"idgId": "789",
"serialNumber": "789",
"comment": "item consists of items",
"owner": "resource:org.dps.track.Assembler#BU2",
"items": [
"resource:org.dps.track.Item#I1",
"resource:org.dps.track.Item#I2"
]
}
Then if i make a transaction I3 changes owner but its components have still previous owner. How can i make I1 and I2 change owner automatically when I3 changes the owner. Is it possible to achieve this? I will be thankful for any help or guidance.

Answer 1

something like this (note that this is sample code, there may be more efficient ways to do it eg. aggregate all the 'related Items' that are affected by change of ownership, and then do one single updateAll() call to update the Item registry - example here) - also note I used async / await (available in Node 8 as its far more readable).
note my transaction model is:
transaction Trade {
--> Item item
--> Assembler newOwner
}
UPDATED: you ALSO need your asset Item to have --> Assembler owner as the resource class (to build a relationship instance with) and not -->BU owner` which is an abstract class.
in the model file (ie Assembler is a participant resource)
/**
* Sample transaction processor function.
* #param {org.dps.track.Trade } trade The sample transaction instance.
* #transaction
*/
async function tradeCommodity(trade) {
const factory = getFactory();
trade.item.owner = trade.newOwner;
var list = [];
if (trade.item.items && trade.item.items.length > 0) {
trade.item.items.forEach((asset) => {
list.push(asset);
});
}
const assetRegistry = await getAssetRegistry('org.dps.track.Item');
// persist the state of the current ITEM
await assetRegistry.update(trade.item);
for (var i = 0; i < list.length; ++i) {
let res = await assetRegistry.get(list[i].getIdentifier());
res.owner = factory.newRelationship('org.dps.track', 'Assembler', trade.newOwner.getIdentifier());
// persist the state of the ITEM with new owner as a relationship
await assetRegistry.update(res);
}
}