Implement support for starting transactions without immediately execu…

…ting them

.eslintrc.js

@@ -23,5 +23,6 @@ module.exports = {
   env: {
     node: true,
     mocha: true,
+    es6: true,
   },
 };

src/transaction.js

@@ -17,6 +17,14 @@ export default class Transaction extends EventEmitter {
     super();
 
     const txid = (this.txid = uniqueId('trx'));
+    if (!container) {
+      this.initPromise = new Promise((resolve, reject) => {
+        this.initRejectFn = reject;
+        container = (transactor) => {
+          resolve(transactor);
+        };
+      });
+    }
 
     this.client = client;
     this.logger = client.logger;
@@ -67,7 +75,12 @@ export default class Transaction extends EventEmitter {
             }
             return null;
           })
-          .catch((e) => this._rejecter(e));
+          .catch((e) => {
+            if (this.initRejectFn) {
+              this.initRejectFn();
+            }
+            return this._rejecter(e);
+          });
 
         return new Promise((resolver, rejecter) => {
           this._resolver = resolver;

src/util/make-knex.js

@@ -34,12 +34,21 @@ function initContext(knexFn) {
       return batchInsert(this, table, batch, chunkSize);
     },
 
-    // Runs a new transaction, taking a container and returning a promise
-    // for when the transaction is resolved.
+    // Creates a new transaction.
+    // If container is provided, returns a promise for when the transaction is resolved.
+    // If container is not provided, returns a promise with a transaction that is resolved
+    // when transaction is ready to be used.
     transaction(container, config) {
       const trx = this.client.transaction(container, config);
       trx.userParams = this.userParams;
-      return trx;
+
+      if (container) {
+        return trx;
+      }
+      // If no container was passed, assume user wants to get a transaction and use it directly
+      else {
+        return trx.initPromise;
+      }
     },
 
     // Typically never needed, initializes the pool for a knex client.

test/unit/knex.js

@@ -223,6 +223,27 @@ describe('knex', () => {
     });
   });
 
+  it('supports direct retrieval of a transaction without a callback', (done) => {
+    const knex = Knex(sqliteConfig);
+    const trxPromise = knex.transaction();
+
+    trxPromise
+      .then((trx) => {
+        expect(trx.client.transacting).to.equal(true);
+        knex
+          .transacting(trx)
+          .select(knex.raw('SELECT 1 AS 1'))
+          .then((result) => {
+            expect(result).to.equal(1);
+            done();
+          });
+        return trx.commit();
+      })
+      .then(() => {
+        done();
+      });
+  });
+
   it('creating transaction copy with user params should throw an error', (done) => {
     const knex = Knex(sqliteConfig);
 

types/knex.d.ts

@@ -43,7 +43,7 @@ interface Knex extends Knex.QueryInterface {
 
   raw: Knex.RawBuilder;
   transaction<T>(
-    transactionScope: (trx: Knex.Transaction) => Promise<T> | Bluebird<T> | void
+    transactionScope?: (trx: Knex.Transaction) => Promise<T> | Bluebird<T> | void
   ): Bluebird<T>;
   destroy(callback: Function): void;
   destroy(): Bluebird<void>;