Javascript cant update assets in for-loop

Question

I am trying to use for-loop in the transaction. The for-loop basically creates new assets, ie. I am creating a new asset on each iteration.

The problem is that each time the loop iterates the value of vals.length remains zero(0). And if I try to do console.log(vals) then too it shows null array even when loop iterates for i=1,2,3...

But once whole transaction function gets completed then I am able to see the assets in UI.

model.cto

asset Net identified by NetNumber{
    o String NetNumber
    o Integer totaltransaction
}

transaction GenerateNet {

}

logic.js

/**
* submit an order
* @param {org.demo.invoice.GenerateNet}
* @transaction
*/
async function GenerateNet(){
    var amt = [200, 500, 700];
    var netNumber = ['aa', 'bb', 'cc'];
    for(var i=0; i < amt.length; i++){
        let netRegistry = await getAssetRegistry('org.demo.invoice.Net');
        let vals = await netRegistry.getAll();
        console.log(vals.length); 
        console.log(vals);
        let newNetting = factory.newResource('org.demo.invoice','Net', netNumber);
        newNetting.totaltransaction = amt[i];
        await nettingRegistry.add(newNetting);
    }
}

Answer 1

Your for-loop will not wait for the asynchronous tasks to finish before continuing to the next iteration. What you could do is use recursion instead:

var amt = [200, 500, 700];
var netNumber = ['aa', 'bb', 'cc'];

async function GenerateNet(i = 0){
    let netRegistry = await getAssetRegistry('org.demo.invoice.Net');
    let vals = await netRegistry.getAll();
    
    console.log(vals.length); 
    console.log(vals);
    
    let newNetting = factory.newResource('org.demo.invoice','Net', netNumber);
    
    newNetting.totaltransaction = amt[i];
    
    await nettingRegistry.add(newNetting);

    const nextIndex = i++;
    if (nextIndex < amt.length) {
        return GenerateNet(nextIndex);
    }
}

await GenerateNet();
// All iterations have finished