From 1e5339121fe3bbbf5aa447941d0d7138654389e5 Mon Sep 17 00:00:00 2001
From: Vitaly Tomilov <vitaly-t@users.noreply.github.com>
Date: Sun, 24 Dec 2017 00:09:53 +0000
Subject: [PATCH 1/3] refactoring database code

Starting to refactor the database code for better use of promises + ES6 generators, to prepare for ES7 await/async.
---
 .../Postgres/PostgresStorageAdapter.js        | 49 ++++++++-----------
 1 file changed, 20 insertions(+), 29 deletions(-)

diff --git a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
index 4f44c1f946..a8bc2fc781 100644
--- a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
+++ b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
@@ -836,35 +836,26 @@ export class PostgresStorageAdapter {
   // Returns a Promise.
   deleteFields(className, schema, fieldNames) {
     debug('deleteFields', className, fieldNames);
-    return Promise.resolve()
-      .then(() => {
-        fieldNames = fieldNames.reduce((list, fieldName) => {
-          const field = schema.fields[fieldName]
-          if (field.type !== 'Relation') {
-            list.push(fieldName);
-          }
-          delete schema.fields[fieldName];
-          return list;
-        }, []);
-
-        const values = [className, ...fieldNames];
-        const columns = fieldNames.map((name, idx) => {
-          return `$${idx + 2}:name`;
-        }).join(', DROP COLUMN');
-
-        const doBatch = (t) => {
-          const batch = [
-            t.none('UPDATE "_SCHEMA" SET "schema"=$<schema> WHERE "className"=$<className>', {schema, className})
-          ];
-          if (values.length > 1) {
-            batch.push(t.none(`ALTER TABLE $1:name DROP COLUMN ${columns}`, values));
-          }
-          return batch;
-        }
-        return this._client.tx((t) => {
-          return t.batch(doBatch(t));
-        });
-      });
+    fieldNames = fieldNames.reduce((list, fieldName) => {
+      const field = schema.fields[fieldName]
+      if (field.type !== 'Relation') {
+        list.push(fieldName);
+      }
+      delete schema.fields[fieldName];
+      return list;
+    }, []);
+
+    const values = [className, ...fieldNames];
+    const columns = fieldNames.map((name, idx) => {
+      return `$${idx + 2}:name`;
+    }).join(', DROP COLUMN');
+
+    return this._client.tx(function * (t) => {
+      yield t.none('UPDATE "_SCHEMA" SET "schema"=$<schema> WHERE "className"=$<className>', {schema, className});
+      if (values.length > 1) {
+        yield t.none(`ALTER TABLE $1:name DROP COLUMN ${columns}`, values);
+      }
+    });
   }
 
   // Return a promise for all schemas known to this adapter, in Parse format. In case the

From 4f6d907f5688871e1ae08253f5bcca74fc3e0d83 Mon Sep 17 00:00:00 2001
From: Vitaly Tomilov <vitaly-t@users.noreply.github.com>
Date: Sun, 24 Dec 2017 00:13:57 +0000
Subject: [PATCH 2/3] Update PostgresStorageAdapter.js

---
 src/Adapters/Storage/Postgres/PostgresStorageAdapter.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
index a8bc2fc781..9a783524d8 100644
--- a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
+++ b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
@@ -850,7 +850,7 @@ export class PostgresStorageAdapter {
       return `$${idx + 2}:name`;
     }).join(', DROP COLUMN');
 
-    return this._client.tx(function * (t) => {
+    return this._client.tx(function * (t) {
       yield t.none('UPDATE "_SCHEMA" SET "schema"=$<schema> WHERE "className"=$<className>', {schema, className});
       if (values.length > 1) {
         yield t.none(`ALTER TABLE $1:name DROP COLUMN ${columns}`, values);

From 84438049b21f54f492736575aeb973841a066af9 Mon Sep 17 00:00:00 2001
From: Vitaly Tomilov <vitaly-t@users.noreply.github.com>
Date: Sun, 24 Dec 2017 11:16:04 +0000
Subject: [PATCH 3/3] Update PostgresStorageAdapter.js

naming the transaction.
---
 src/Adapters/Storage/Postgres/PostgresStorageAdapter.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
index 9a783524d8..433e63ef92 100644
--- a/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
+++ b/src/Adapters/Storage/Postgres/PostgresStorageAdapter.js
@@ -850,7 +850,7 @@ export class PostgresStorageAdapter {
       return `$${idx + 2}:name`;
     }).join(', DROP COLUMN');
 
-    return this._client.tx(function * (t) {
+    return this._client.tx('delete-fields', function * (t) {
       yield t.none('UPDATE "_SCHEMA" SET "schema"=$<schema> WHERE "className"=$<className>', {schema, className});
       if (values.length > 1) {
         yield t.none(`ALTER TABLE $1:name DROP COLUMN ${columns}`, values);