From 00c618c2ca9c7a44738b656df8cfb016c9d22037 Mon Sep 17 00:00:00 2001
From: Rasmus Porsager <rasmus@porsager.com>
Date: Fri, 13 Aug 2021 16:09:29 +0200
Subject: [PATCH] transform.column.to support

---
 lib/backend.js | 10 +++++-----
 lib/index.js   | 40 +++++++++++++++++++++++++++++++++++-----
 lib/types.js   |  4 ++++
 tests/index.js | 12 ++++++++++++
 4 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/lib/backend.js b/lib/backend.js
index cfabb80a..c8c44ae5 100644
--- a/lib/backend.js
+++ b/lib/backend.js
@@ -122,12 +122,12 @@ function Backend({
 
       backend.query.raw
         ? (row[i] = value)
-        : (row[column.name] = transform.value ? transform.value(value) : value)
+        : (row[column.name] = transform.value.from ? transform.value.from(value) : value)
     }
 
     backend.query.stream
-      ? backend.query.stream(transform.row ? transform.row(row) : row, backend.query.result)
-      : (backend.query.result[rows++] = transform.row ? transform.row(row) : row)
+      ? backend.query.stream(transform.row.from ? transform.row.from(row) : row, backend.query.result)
+      : (backend.query.result[rows++] = transform.row.from ? transform.row.from(row) : row)
   }
 
   /* c8 ignore next 3 */
@@ -208,8 +208,8 @@ function Backend({
       while (x[index++] !== 0);
       const type = x.readInt32BE(index + 6)
       backend.query.statement.columns[i] = {
-        name: transform.column
-          ? transform.column(x.toString('utf8', start, index - 1))
+        name: transform.column.from
+          ? transform.column.from(x.toString('utf8', start, index - 1))
           : x.toString('utf8', start, index - 1),
         parser: parsers[type],
         type
diff --git a/lib/index.js b/lib/index.js
index 6edf49ca..1998ccd4 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -8,11 +8,14 @@ const {
   mergeUserTypes,
   arraySerializer,
   arrayParser,
+  fromPascal,
+  fromCamel,
+  fromKebab,
   inferType,
   toPascal,
-  entries,
   toCamel,
   toKebab,
+  entries,
   escape,
   types,
   END
@@ -33,6 +36,9 @@ Object.assign(Postgres, {
   toPascal,
   toCamel,
   toKebab,
+  fromPascal,
+  fromCamel,
+  fromKebab,
   BigInt: {
     to: 20,
     from: [20],
@@ -52,6 +58,7 @@ function Postgres(a, b) {
   const options = parseOptions(a, b)
 
   const max = Math.max(1, options.max)
+      , transform = options.transform
       , connections = Queue()
       , all = []
       , queries = Queue()
@@ -532,7 +539,9 @@ function Postgres(a, b) {
   function selectHelper(first, columns, xargs, types) {
     return entries(first).reduce((acc, [k, v]) =>
       acc + (!columns.length || columns.indexOf(k) > -1
-        ? (acc ? ',' : '') + parseValue(v, xargs, types) + ' as ' + escape(k)
+        ? (acc ? ',' : '') + parseValue(v, xargs, types) + ' as ' + escape(
+          transform.column.to ? transform.column.to(k) : k
+        )
         : ''
       ),
       ''
@@ -553,13 +562,17 @@ function Postgres(a, b) {
 
   function equalsHelper(first, columns, xargs, types) {
     return (columns.length ? columns : Object.keys(first)).reduce((acc, k) =>
-      acc + (acc ? ',' : '') + escape(k) + ' = ' + parseValue(first[k], xargs, types),
+      acc + (acc ? ',' : '') + escape(
+        transform.column.to ? transform.column.to(k) : k
+      ) + ' = ' + parseValue(first[k], xargs, types),
       ''
     )
   }
 
   function escapeHelper(xs) {
-    return xs.reduce((acc, x) => acc + (acc ? ',' : '') + escape(x), '')
+    return xs.reduce((acc, x) => acc + (acc ? ',' : '') + escape(
+      transform.column.to ? transform.column.to(x) : x
+    ), '')
   }
 
   function parseValue(x, xargs, types) {
@@ -623,7 +636,7 @@ function parseOptions(a, b) {
     prepare         : 'prepare' in o ? o.prepare : 'no_prepare' in o ? !o.no_prepare : true,
     onnotice        : o.onnotice,
     onparameter     : o.onparameter,
-    transform       : Object.assign({}, o.transform),
+    transform       : parseTransform(o.transform || {}),
     connection      : Object.assign({ application_name: 'postgres.js' }, o.connection),
     target_session_attrs: o.target_session_attrs || url.query.target_session_attrs || env.PGTARGETSESSIONATTRS,
     debug           : o.debug,
@@ -633,6 +646,23 @@ function parseOptions(a, b) {
   )
 }
 
+function parseTransform(x) {
+  return {
+    column: {
+      from: typeof x.column === 'function' ? x.column : x.column && x.column.from,
+      to: x.column && x.column.to
+    },
+    value: {
+      from: typeof x.value === 'function' ? x.value : x.value && x.value.from,
+      to: x.value && x.value.to
+    },
+    row: {
+      from: typeof x.row === 'function' ? x.row : x.row && x.row.from,
+      to: x.row && x.row.to
+    }
+  }
+}
+
 function parseSSL(x) {
   return x !== 'disable' && x !== 'false' && x
 }
diff --git a/lib/types.js b/lib/types.js
index b372e70b..644dd22b 100644
--- a/lib/types.js
+++ b/lib/types.js
@@ -172,6 +172,10 @@ module.exports.toPascal = x => {
 
 module.exports.toKebab = x => x.replace(/_/g, '-')
 
+module.exports.fromCamel = x => x.replace(/([A-Z])/g, '_$1').toLowerCase()
+module.exports.fromPascal = x => (x.slice(0, 1) + x.slice(1).replace(/([A-Z])/g, '_$1')).toLowerCase()
+module.exports.fromKebab = x => x.replace(/-/g, '_')
+
 module.exports.errorFields = entries({
   S: 'severity_local',
   V: 'severity',
diff --git a/tests/index.js b/tests/index.js
index 58905432..51020cdd 100644
--- a/tests/index.js
+++ b/tests/index.js
@@ -1037,6 +1037,18 @@ t('Transform value', async() => {
   return [1, (await sql`select 'wat' as x`)[0].x]
 })
 
+t('Transform columns from', async() => {
+  const sql = postgres({ ...options, transform: { column: { to: postgres.fromCamel, from: postgres.toCamel } } })
+  await sql`create table test (a_test int, b_test text)`
+  await sql`insert into test ${ sql([{ aTest: 1, bTest: 1 }]) }`
+  await sql`update test set ${ sql({ aTest: 2, bTest: 2 }) }`
+  return [
+    2,
+    (await sql`select ${ sql('aTest', 'bTest') } from test`)[0].aTest,
+    await sql`drop table test`
+  ]
+})
+
 t('Unix socket', async() => {
   const sql = postgres({
     ...options,