feat: Add commaNewline option for comma placement control [DLH.io]

AUTHORS

@@ -72,3 +72,4 @@ Wylie Conlon <wylie@superblockshq.com>
 Xin Hu <hoosin.git@gmail.com>
 Zhongxian Liang <zhongxian.liang@shopee.com>
 0xflotus <0xflotus@gmail.com>
+Swayam Shah(dlh.io) <swayam@aicg.com>

README.md

@@ -183,6 +183,7 @@ All fields are optional and all fields that are not specified will be filled wit
 - [**`identifierCase`**](docs/identifierCase.md) uppercases or lowercases identifiers. (**experimental!**)
 - [**`indentStyle`**](docs/indentStyle.md) defines overall indentation style. (**deprecated!**)
 - [**`logicalOperatorNewline`**](docs/logicalOperatorNewline.md) newline before or after boolean operator (AND, OR, XOR).
+- [**`commaNewline`**](docs/commaNewline.md) newline before or after comma seperating multiple columns/tables.
 - [**`expressionWidth`**](docs/expressionWidth.md) maximum number of characters in parenthesized expressions to be kept on single line.
 - [**`linesBetweenQueries`**](docs/linesBetweenQueries.md) how many newlines to insert between queries.
 - [**`denseOperators`**](docs/denseOperators.md) packs operators densely without spaces.

docs/commaNewline.md

@@ -0,0 +1,38 @@
+# commaNewline
+
+Decides newline placement before or after commas seperating columns/tables.
+
+## Options
+
+- `"after"` (default) adds newline after the comma.
+- `"before"` adds newline before the comma with a following space.
+
+### after
+
+```sql
+SELECT
+  name,
+  age,
+  height
+FROM
+  persons
+WHERE
+  age > 10
+  AND height < 150
+  OR occupation IS NULL
+```
+
+### before
+
+```sql
+SELECT
+  name
+  , age
+  , height
+FROM
+  persons
+WHERE
+  age > 10 AND
+  height < 150 OR
+  occupation IS NULL
+```

src/FormatOptions.ts

@@ -10,6 +10,7 @@ export type DataTypeCase = KeywordCase;
 export type FunctionCase = KeywordCase;
 
 export type LogicalOperatorNewline = 'before' | 'after';
+export type CommaNewline = LogicalOperatorNewline;
 
 export interface FormatOptions {
   tabWidth: number;
@@ -20,6 +21,7 @@ export interface FormatOptions {
   functionCase: FunctionCase;
   indentStyle: IndentStyle;
   logicalOperatorNewline: LogicalOperatorNewline;
+  commaNewline: CommaNewline;
   expressionWidth: number;
   linesBetweenQueries: number;
   denseOperators: boolean;

src/formatter/ExpressionFormatter.ts

@@ -341,7 +341,11 @@ export default class ExpressionFormatter {
 
   private formatComma(_node: CommaNode) {
     if (!this.inline) {
-      this.layout.add(WS.NO_SPACE, ',', WS.NEWLINE, WS.INDENT);
+      if (this.cfg.commaNewline === 'before') {
+        this.layout.add(WS.NEWLINE, WS.INDENT, ',', WS.SPACE);
+      } else {
+        this.layout.add(WS.NO_SPACE, ',', WS.NEWLINE, WS.INDENT);
+      }
     } else {
       this.layout.add(WS.NO_SPACE, ',', WS.SPACE);
     }

src/sqlFormatter.ts

@@ -48,6 +48,7 @@ const defaultOptions: FormatOptions = {
   functionCase: 'preserve',
   indentStyle: 'standard',
   logicalOperatorNewline: 'before',
+  commaNewline: 'after',
   expressionWidth: 50,
   linesBetweenQueries: 1,
   denseOperators: false,

test/behavesLikeSqlFormatter.ts

@@ -13,6 +13,7 @@ import supportsIndentStyle from './options/indentStyle.js';
 import supportsLinesBetweenQueries from './options/linesBetweenQueries.js';
 import supportsNewlineBeforeSemicolon from './options/newlineBeforeSemicolon.js';
 import supportsLogicalOperatorNewline from './options/logicalOperatorNewline.js';
+import supportsCommaNewline from './options/commaNewline.js';
 import supportsParamTypes from './options/paramTypes.js';
 import supportsWindowFunctions from './features/windowFunctions.js';
 import supportsFunctionCase from './options/functionCase.js';
@@ -36,6 +37,7 @@ export default function behavesLikeSqlFormatter(format: FormatFn) {
   supportsExpressionWidth(format);
   supportsNewlineBeforeSemicolon(format);
   supportsLogicalOperatorNewline(format);
+  supportsCommaNewline(format);
   supportsParamTypes(format);
   supportsWindowFunctions(format);
 

test/options/commaNewline.ts

@@ -0,0 +1,37 @@
+import dedent from 'dedent-js';
+
+import { FormatFn } from '../../src/sqlFormatter.js';
+
+export default function supportsCommaNewline(format: FormatFn) {
+  it('by default adds newline after comma', () => {
+    const result = format(`SELECT id, first_name, last_name, email FROM users;`);
+    expect(result).toBe(
+      dedent`
+      SELECT
+        id,
+        first_name,
+        last_name,
+        email
+      FROM
+        users;
+    `
+    );
+  });
+
+  it('supports newline before comma', () => {
+    const result = format(`SELECT id, first_name, last_name, email FROM users;`, {
+      commaNewline: 'before',
+    });
+    expect(result).toBe(
+      dedent`
+      SELECT
+        id
+        , first_name
+        , last_name
+        , email
+      FROM
+        users;
+    `
+    );
+  });
+}