Add transactor.parentTransaction (#5567)

lib/execution/transaction.js

@@ -219,6 +219,10 @@ class Transaction extends EventEmitter {
           return makeTransactor(this, connection, trxClient);
         })
         .then((transactor) => {
+          this.transactor = transactor;
+          if (this.outerTx) {
+            transactor.parentTransaction = this.outerTx.transactor;
+          }
           transactor.executionPromise = executionPromise;
 
           // If we've returned a "thenable" from the transaction container, assume

test/integration/execution/transaction.js

@@ -810,5 +810,27 @@ module.exports = function (knex) {
         // closed it. (Ex: this was the case for OracleDB before fixing #3721)
       });
     });
+
+    it('exposes the parent transaction', async () => {
+      await knex.transaction(async (trx1) => {
+        expect(trx1.parentTransaction).to.equal(undefined);
+
+        await trx1.transaction(async (trx2) => {
+          expect(trx2.parentTransaction).to.equal(trx1);
+        });
+
+        await trx1.transaction(async (trx2) => {
+          expect(trx2.parentTransaction).to.equal(trx1);
+
+          await trx2.transaction(async (trx3) => {
+            expect(trx3.parentTransaction).to.equal(trx2);
+          });
+
+          await trx2.transaction(async (trx3) => {
+            expect(trx3.parentTransaction).to.equal(trx2);
+          });
+        });
+      });
+    });
   });
 };

types/index.d.ts

@@ -2323,6 +2323,7 @@ declare namespace Knex {
   interface Transaction<TRecord extends {} = any, TResult = any[]>
     extends Knex<TRecord, TResult> {
     executionPromise: Promise<TResult>;
+    parentTransaction?: Transaction;
     isCompleted: () => boolean;
 
     query<TRecord extends {} = any, TResult = void>(