Hyperledger Composer Query using relation

Question

I have made a query in Hyperledger Composer where in the query tries to search for all invoices of a borrower. The borrower is a participant of the invoice asset:

asset Invoice identified by invoiceId {
  o String invoiceId
  o String invoiceRef optional
  o DateTime dateCreated
  o String type
  o DateTime invoiceOrPurchaseDate optional
  o Double amount
  o DateTime invoiceDueDate optional
  o String paymentStatus optional
  o Boolean overdue
  o Double outstandingBalance
  --> Participant borrower
  --> Participant lender
}

I need a query that will return all invoices of a borrower and I did this in Hyperledger composer by coding below:

query QInvoiceByBorrower {
    description: "Select invoice by borrower"
    statement:
        SELECT org.n.blockchaindemo.Invoice
            WHERE (_$borrower == borrower)
}

But when I try to call the query through REST API, I get [] empty result as below:

http://10.10.4.244:3000/api/queries/QInvoiceByBorrower?borrower=resource:org.n.blockchaindemo.User#1381991

May I know how to create a query that will search using a foreign relation in Hyperledger Composer?

Answer 1

 you need to refer to your specific Participant type i.e. User rather that the system type Participant. So the last part of your Invoice will be:

  o Double outstandingBalance
  --> User borrower
  --> User lender
 }