Hyperledger getParticipants - node.js

Question

function Exchange(exchange){
// We do the actual exchange here:
// We first need to get both actual nodes:
var nodeIdFrom=exchange.nodeIdFrom;
var quantity =exchange.quantity;
var price = exchange.price;
var nodeIdTo =exchange.nodeIdTo;
return getParticipantRegistry('org.acme.mynetwork.Node')
.then(function(ParticipantRegistry){
ParticipantRegistry.get(nodeIdFrom)
.then(function(Participant){
Participant.Need=Participant.Need+quantity;
Participant.Balance_account=Participant.Balance_account+quantity*price;
return ParticipantRegistry.update(Participant);
});
});
I'm trying to execute a transaction defined as:
transaction Exchange{
o String nodeIdFrom
o String nodeIdTo
o Double quantity
o Double Price
}
To execute a transaction (we take money somewhere and put it somewhere else). With only the ids of the nodes as a parameter.
But right now that function does not work, you can execute it on the playground but my node is not modified.
Is it possible to apply a transaction without giving node as Node (node is a Participant).

Answer 1

it should work - here's an example (Using a fictitious sample 'Trader' Network and like you, I have defined 'qty' as a 'Double' in the Transaction model definition itself) of updating an Asset by a specific identifier (you're doing something similar - Participant by ID) and then - updating the asset's quantity using the Promises chain below. Suggest to use console.log() for outputs too when debugging.
So - given Transaction model:
transaction TraderById {
o String tradeId
o String tradingSymbol
o Double qty
}
and an Asset modeled as:
asset Commodity identified by tradingSymbol {
o String tradingSymbol
o String description
o String mainExchange
o Double quantity
--> Trader owner
}
you can update the Asset quantity ('quantity') as follows:
/**
*
* #param {org.acme.trading.TraderById} tradeById - the trade to be processed
* #transaction
*/
function TradeById(tradeById){
var commodityRegistry;
return getAssetRegistry('org.acme.trading.Commodity')
.then(function(registry){
commodityRegistry=registry;
return commodityRegistry.get(tradeById.tradingSymbol);
})
.then(function(result){
result.quantity-=tradeById.qty;
return commodityRegistry.update(result);
});
}