Custom delimiters (#1064)

* frontmatter functions now exported as curried constructors

* changed formats.js to accomodate frontmatter.js changes

* can only use custom delimiters if format is specified

* reverting changes

* updated tests to reflect changes

* created tests for custom delimiters

* updated docs to reflect addition of custom delimiter configuration

* formatByExtension no longer takes custom delimiter

* missed some formatByExtension calls

* Edited the docs according to suggestions

* Throws an error if a custom delimiter is set without declaring frontmatter format

* Throws error if custom delimiter set without explicit and proper frontmatter format being declared

* example config file set to proper defaults

* moved frontmatterFormats to formats

* Update .all-contributorsrc

* updated contributions

* Clarify docs

.all-contributorsrc

@@ -710,6 +710,17 @@
         "code"
       ]
     },
+    {
+      "login": "Swieckowski",
+      "name": "Swieckowski",
+      "avatar_url": "https://avatars0.githubusercontent.com/u/31023010?v=4",
+      "profile": "https://www.linkedin.com/in/arthur-swieckowski/",
+      "contributions": [
+        "code",
+        "doc",
+        "test"
+      ]
+    },
     {
       "login": "pixelastic",
       "name": "Tim Carry",

README.md

@@ -1,6 +1,5 @@
 # Netlify CMS
-
+[![All Contributors](https://img.shields.io/badge/all_contributors-87-orange.svg)](#contributors)
-[![All Contributors](https://img.shields.io/badge/all_contributors-86-orange.svg)](#contributors)
 [![Open Source Helpers](https://www.codetriage.com/netlify/netlify-cms/badges/users.svg)](https://www.codetriage.com/netlify/netlify-cms)
 [![](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/netlify/netlifycms)
 
@@ -62,8 +61,8 @@ Thanks goes to these wonderful people ([emoji key](https://github.com/kentcdodds
 | [<img src="https://avatars0.githubusercontent.com/u/250958?v=4" width="100px;"/><br /><sub><b>Etienne Bernard</b></sub>](https://github.com/ebernard)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=ebernard "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/871660?v=4" width="100px;"/><br /><sub><b>Eli Williamson</b></sub>](http://eliwilliamson.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=eliwilliamson "Code") [🎨](#design-eliwilliamson "Design") | [<img src="https://avatars0.githubusercontent.com/u/858837?v=4" width="100px;"/><br /><sub><b>Covington Doan</b></sub>](https://www.covingtondoan.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=covingtondoan "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/1299080?v=4" width="100px;"/><br /><sub><b>Lennart Ziburski</b></sub>](http://lennartziburski.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=ziburski "Code") [🎨](#design-ziburski "Design") [📖](https://github.com/netlify/netlify-cms/commits?author=ziburski "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/387640?v=4" width="100px;"/><br /><sub><b>Darrel O'Pry</b></sub>](http://darrelopry.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=dopry "Code") [🚇](#infra-dopry "Infrastructure (Hosting, Build-Tools, etc)") [⚠️](https://github.com/netlify/netlify-cms/commits?author=dopry "Tests") | [<img src="https://avatars1.githubusercontent.com/u/13856868?v=4" width="100px;"/><br /><sub><b>Erin Symons</b></sub>](https://github.com/yourfrienderin)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=yourfrienderin "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/5200555?v=4" width="100px;"/><br /><sub><b>Austin Green</b></sub>](https://github.com/AustinGreen)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=AustinGreen "Documentation") [💡](#example-AustinGreen "Examples") |
 | [<img src="https://avatars2.githubusercontent.com/u/799360?v=4" width="100px;"/><br /><sub><b>Bryan Robinson</b></sub>](http://bryanlrobinson.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=brob "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/561983?v=4" width="100px;"/><br /><sub><b>Darren</b></sub>](https://github.com/dardub)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=dardub "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/576512?v=4" width="100px;"/><br /><sub><b>Richard Pullinger</b></sub>](http://www.richardpullinger.com)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=rpullinger "Code") | [<img src="https://avatars1.githubusercontent.com/u/3718939?v=4" width="100px;"/><br /><sub><b>Taylor Bryant</b></sub>](https://taylorbryant.blog)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=taylorbryant "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/5881826?v=4" width="100px;"/><br /><sub><b>kvanerkelens</b></sub>](https://github.com/kvanerkelens)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=kvanerkelens "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/8291663?v=4" width="100px;"/><br /><sub><b>Patrick Sier</b></sub>](https://patsier.com/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=pjsier "Code") | [<img src="https://avatars2.githubusercontent.com/u/6132191?v=4" width="100px;"/><br /><sub><b>Christian Nolte</b></sub>](http://noltech.net)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=drlogout "Code") |
 | [<img src="https://avatars1.githubusercontent.com/u/3818?v=4" width="100px;"/><br /><sub><b>Edward Betts</b></sub>](http://edwardbetts.com/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=EdwardBetts "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/8771435?v=4" width="100px;"/><br /><sub><b>Josh Hardman</b></sub>](https://github.com/jhardman0830)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=jhardman0830 "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/11616378?v=4" width="100px;"/><br /><sub><b>Mantas</b></sub>](https://behance.net/mistermantas)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=mistermantas "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/5244986?v=4" width="100px;"/><br /><sub><b>Marco Biedermann</b></sub>](https://www.marcobiedermann.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=marcobiedermann "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/7525670?v=4" width="100px;"/><br /><sub><b>Max Stoiber</b></sub>](https://mxstbr.blog/newsletter)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=mxstbr "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/89368?v=4" width="100px;"/><br /><sub><b>Vyacheslav Matyukhin</b></sub>](http://berekuk.ru)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=berekuk "Documentation") | [<img src="https://avatars1.githubusercontent.com/u/9059048?v=4" width="100px;"/><br /><sub><b>jimmaaay</b></sub>](https://jimmythompson.me)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=jimmaaay "Code") |
-| [<img src="https://avatars3.githubusercontent.com/u/802086?v=4" width="100px;"/><br /><sub><b>Luís Miguel</b></sub>](https://github.com/Quicksaver)<br />[🐛](https://github.com/netlify/netlify-cms/issues?q=author%3AQuicksaver "Bug reports") [💻](https://github.com/netlify/netlify-cms/commits?author=Quicksaver "Code") | [<img src="https://avatars2.githubusercontent.com/u/357379?v=4" width="100px;"/><br /><sub><b>Chris Swithinbank</b></sub>](http://chrisswithinbank.net/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=delucis "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/1262221?v=4" width="100px;"/><br /><sub><b>remmah</b></sub>](https://github.com/remmah)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=remmah "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/29388?v=4" width="100px;"/><br /><sub><b>Sumeet Jain</b></sub>](http://sumeetjain.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=sumeetjain "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/26816046?v=4" width="100px;"/><br /><sub><b>Sagar Khatri</b></sub>](https://github.com/ragasirtahk)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=ragasirtahk "Documentation") [💡](#example-ragasirtahk "Examples") | [<img src="https://avatars0.githubusercontent.com/u/8182932?v=4" width="100px;"/><br /><sub><b>Kevin Doocey</b></sub>](https://www.dooceykev.in)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=Doocey "Code") | [<img src="https://avatars2.githubusercontent.com/u/283419?v=4" width="100px;"/><br /><sub><b>Tim Carry</b></sub>](http://www.pixelastic.com/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Code") [🎨](#design-pixelastic "Design") [📖](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Documentation") |
+| [<img src="https://avatars3.githubusercontent.com/u/802086?v=4" width="100px;"/><br /><sub><b>Luís Miguel</b></sub>](https://github.com/Quicksaver)<br />[🐛](https://github.com/netlify/netlify-cms/issues?q=author%3AQuicksaver "Bug reports") [💻](https://github.com/netlify/netlify-cms/commits?author=Quicksaver "Code") | [<img src="https://avatars2.githubusercontent.com/u/357379?v=4" width="100px;"/><br /><sub><b>Chris Swithinbank</b></sub>](http://chrisswithinbank.net/)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=delucis "Documentation") | [<img src="https://avatars3.githubusercontent.com/u/1262221?v=4" width="100px;"/><br /><sub><b>remmah</b></sub>](https://github.com/remmah)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=remmah "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/29388?v=4" width="100px;"/><br /><sub><b>Sumeet Jain</b></sub>](http://sumeetjain.com)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=sumeetjain "Documentation") | [<img src="https://avatars2.githubusercontent.com/u/26816046?v=4" width="100px;"/><br /><sub><b>Sagar Khatri</b></sub>](https://github.com/ragasirtahk)<br />[📖](https://github.com/netlify/netlify-cms/commits?author=ragasirtahk "Documentation") [💡](#example-ragasirtahk "Examples") | [<img src="https://avatars0.githubusercontent.com/u/8182932?v=4" width="100px;"/><br /><sub><b>Kevin Doocey</b></sub>](https://www.dooceykev.in)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=Doocey "Code") | [<img src="https://avatars0.githubusercontent.com/u/31023010?v=4" width="100px;"/><br /><sub><b>Swieckowski</b></sub>](https://www.linkedin.com/in/arthur-swieckowski/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=Swieckowski "Code") [📖](https://github.com/netlify/netlify-cms/commits?author=Swieckowski "Documentation") [⚠️](https://github.com/netlify/netlify-cms/commits?author=Swieckowski "Tests") |
-| [<img src="https://avatars0.githubusercontent.com/u/30510616?v=4" width="100px;"/><br /><sub><b>Sol Park</b></sub>](https://github.com/solpark)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=solpark "Code") | [<img src="https://avatars0.githubusercontent.com/u/29218846?v=4" width="100px;"/><br /><sub><b>Michael Romani</b></sub>](https://github.com/michaelromani)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=michaelromani "Code") |
+| [<img src="https://avatars2.githubusercontent.com/u/283419?v=4" width="100px;"/><br /><sub><b>Tim Carry</b></sub>](http://www.pixelastic.com/)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Code") [🎨](#design-pixelastic "Design") [📖](https://github.com/netlify/netlify-cms/commits?author=pixelastic "Documentation") | [<img src="https://avatars0.githubusercontent.com/u/30510616?v=4" width="100px;"/><br /><sub><b>Sol Park</b></sub>](https://github.com/solpark)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=solpark "Code") | [<img src="https://avatars0.githubusercontent.com/u/29218846?v=4" width="100px;"/><br /><sub><b>Michael Romani</b></sub>](https://github.com/michaelromani)<br />[💻](https://github.com/netlify/netlify-cms/commits?author=michaelromani "Code") |
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors](https://github.com/kentcdodds/all-contributors) specification. Contributions of any kind welcome!

src/formats/__tests__/frontmatter.spec.js

@@ -1,4 +1,4 @@
-import { FrontmatterInfer, FrontmatterJSON, FrontmatterTOML, FrontmatterYAML } from '../frontmatter';
+import { FrontmatterInfer, frontmatterJSON, frontmatterTOML, frontmatterYAML } from '../frontmatter';
 
 jest.mock("../../valueObjects/AssetProxy.js");
 
@@ -15,9 +15,21 @@ describe('Frontmatter', () => {
     );
   });
 
-  it('should parse YAML with --- delimiters when it is explicitly set as the format', () => {
+  it('should parse YAML with --- delimiters when it is explicitly set as the format without a custom delimiter', () => {
     expect(
-      FrontmatterYAML.fromFile('---\ntitle: YAML\ndescription: Something longer\n---\nContent')
+      frontmatterYAML().fromFile('---\ntitle: YAML\ndescription: Something longer\n---\nContent')
+    ).toEqual(
+      {
+        title: 'YAML',
+        description: 'Something longer',
+        body: 'Content',
+      }
+      );
+  });
+
+  it('should parse YAML with custom delimiters when it is explicitly set as the format with a custom delimiter', () => {
+    expect(
+      frontmatterYAML("~~~").fromFile('~~~\ntitle: YAML\ndescription: Something longer\n~~~\nContent')
     ).toEqual(
       {
         title: 'YAML',
@@ -62,9 +74,9 @@ describe('Frontmatter', () => {
     );
   });
 
-  it('should parse TOML with +++ delimiters when it is explicitly set as the format', () => {
+  it('should parse TOML with +++ delimiters when it is explicitly set as the format without a custom delimiter', () => {
     expect(
-      FrontmatterTOML.fromFile('+++\ntitle = "TOML"\ndescription = "Front matter"\n+++\nContent')
+      frontmatterTOML("~~~").fromFile('~~~\ntitle = "TOML"\ndescription = "Front matter"\n~~~\nContent')
     ).toEqual(
       {
         title: 'TOML',
@@ -98,9 +110,21 @@ describe('Frontmatter', () => {
     );
   });
 
-  it('should parse JSON with { } delimiters when it is explicitly set as the format', () => {
+  it('should parse JSON with { } delimiters when it is explicitly set as the format without a custom delimiter', () => {
     expect(
-      FrontmatterJSON.fromFile('{\n"title": "The Title",\n"description": "Something longer"\n}\nContent')
+      frontmatterJSON().fromFile('{\n"title": "The Title",\n"description": "Something longer"\n}\nContent')
+    ).toEqual(
+      {
+        title: 'The Title',
+        description: 'Something longer',
+        body: 'Content',
+      }
+      );
+  });
+
+  it('should parse JSON with { } delimiters when it is explicitly set as the format with a custom delimiter', () => {
+    expect(
+      frontmatterJSON("~~~").fromFile('~~~\n"title": "The Title",\n"description": "Something longer"\n~~~\nContent')
     ).toEqual(
       {
         title: 'The Title',
@@ -156,9 +180,10 @@ describe('Frontmatter', () => {
     );
   });
 
-  it('should stringify YAML with --- delimiters when it is explicitly set as the format', () => {
+  it('should stringify YAML with --- delimiters when it is explicitly set as the format without a custom delimiter', 
+  () => {
     expect(
-      FrontmatterYAML.toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'yaml'], title: 'YAML' })
+      frontmatterYAML().toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'yaml'], title: 'YAML' })
     ).toEqual(
       [
         '---',
@@ -173,9 +198,28 @@ describe('Frontmatter', () => {
       );
   });
 
-  it('should stringify TOML with +++ delimiters when it is explicitly set as the format', () => {
+  it('should stringify YAML with --- delimiters when it is explicitly set as the format with a custom delimiter', 
+  () => {
     expect(
-      FrontmatterTOML.toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'toml'], title: 'TOML' })
+      frontmatterYAML("~~~").toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'yaml'], title: 'YAML' })
+    ).toEqual(
+      [
+        '~~~',
+        'tags:',
+        '  - front matter',
+        '  - yaml',
+        'title: YAML',
+        '~~~',
+        'Some content',
+        'On another line\n',
+      ].join('\n')
+      );
+  });
+
+  it('should stringify TOML with +++ delimiters when it is explicitly set as the format without a custom delimiter',
+  () => {
+    expect(
+      frontmatterTOML().toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'toml'], title: 'TOML' })
     ).toEqual(
       [
         '+++',
@@ -188,9 +232,26 @@ describe('Frontmatter', () => {
       );
   });
 
-  it('should stringify JSON with { } delimiters when it is explicitly set as the format', () => {
+  it('should stringify TOML with +++ delimiters when it is explicitly set as the format with a custom delimiter',
+  () => {
     expect(
-      FrontmatterJSON.toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'json'], title: 'JSON' })
+      frontmatterTOML("~~~").toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'toml'], title: 'TOML' })
+    ).toEqual(
+      [
+        '~~~',
+        'tags = ["front matter", "toml"]',
+        'title = "TOML"',
+        '~~~',
+        'Some content',
+        'On another line\n',
+      ].join('\n')
+      );
+  });
+
+  it('should stringify JSON with { } delimiters when it is explicitly set as the format without a custom delimiter', 
+  () => {
+    expect(
+      frontmatterJSON().toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'json'], title: 'JSON' })
     ).toEqual(
       [
         '{',
@@ -205,4 +266,23 @@ describe('Frontmatter', () => {
       ].join('\n')
       );
   });
+
+  it('should stringify JSON with { } delimiters when it is explicitly set as the format with a custom delimiter', 
+  () => {
+    expect(
+      frontmatterJSON("~~~").toFile({ body: 'Some content\nOn another line', tags: ['front matter', 'json'], title: 'JSON' })
+    ).toEqual(
+      [
+        '~~~',
+        '"tags": [',
+        '    "front matter",',
+        '    "json"',
+        '  ],',
+        '  "title": "JSON"',
+        '~~~',
+        'Some content',
+        'On another line\n',
+      ].join('\n')
+      );
+  });
 });

src/formats/formats.js

@@ -1,7 +1,9 @@
 import yamlFormatter from './yaml';
 import tomlFormatter from './toml';
 import jsonFormatter from './json';
-import { FrontmatterInfer, FrontmatterJSON, FrontmatterTOML, FrontmatterYAML } from './frontmatter';
+import { FrontmatterInfer, frontmatterJSON, frontmatterTOML, frontmatterYAML } from './frontmatter';
+
+export const frontmatterFormats = ['yaml-frontmatter','toml-frontmatter','json-frontmatter']
 
 export const supportedFormats = [
   'yml',
@@ -37,24 +39,26 @@ export function formatByExtension(extension) {
   }[extension];
 }
 
-function formatByName(name) {
+function formatByName(name, customDelimiter) {
   return {
     yml: yamlFormatter,
     yaml: yamlFormatter,
     toml: tomlFormatter,
     json: jsonFormatter,
     frontmatter: FrontmatterInfer,
-    'json-frontmatter': FrontmatterJSON,
+    'json-frontmatter': frontmatterJSON(customDelimiter),
-    'toml-frontmatter': FrontmatterTOML,
+    'toml-frontmatter': frontmatterTOML(customDelimiter),
-    'yaml-frontmatter': FrontmatterYAML,
+    'yaml-frontmatter': frontmatterYAML(customDelimiter),
   }[name];
 }
 
 export function resolveFormat(collectionOrEntity, entry) {
+  // Check for custom delimiter
+  const customDelimiter = collectionOrEntity.get('frontmatter_delimiter');
   // If the format is specified in the collection, use that format.
-  const format = collectionOrEntity.get('format');
+  const formatSpecification = collectionOrEntity.get('format');
-  if (format) {
+  if (formatSpecification) {
-    return formatByName(format);
+    return formatByName(formatSpecification, customDelimiter);
   }
 
   // If a file already exists, infer the format from its file extension.
@@ -72,5 +76,5 @@ export function resolveFormat(collectionOrEntity, entry) {
   }
 
   // If no format is specified and it cannot be inferred, return the default.
-  return formatByName('frontmatter');
+  return formatByName('frontmatter', customDelimiter);
 }

src/formats/frontmatter.js

@@ -60,12 +60,14 @@ export const getFormatOpts = format => ({
 }[format]);
 
 class FrontmatterFormatter {
-  constructor(format) {
+  constructor(format, customDelimiter) {
     this.format = getFormatOpts(format);
+    this.customDelimiter = customDelimiter;
   }
 
   fromFile(content) {
     const format = this.format || inferFrontmatterFormat(content);
+    if (this.customDelimiter) this.format.delimiters = this.customDelimiter;
     const result = matter(content, { engines: parsers, ...format });
     return {
       ...result.data,
@@ -78,6 +80,7 @@ class FrontmatterFormatter {
 
     // Stringify to YAML if the format was not set
     const format = this.format || getFormatOpts('yaml');
+    if (this.customDelimiter) this.format.delimiters = this.customDelimiter;
 
     // `sortedKeys` is not recognized by gray-matter, so it gets passed through to the parser
     return matter.stringify(body, meta, { engines: parsers, sortedKeys, ...format });
@@ -85,6 +88,6 @@ class FrontmatterFormatter {
 }
 
 export const FrontmatterInfer = new FrontmatterFormatter();
-export const FrontmatterYAML = new FrontmatterFormatter('yaml');
+export const frontmatterYAML = customDelimiter => new FrontmatterFormatter('yaml', customDelimiter);
-export const FrontmatterTOML = new FrontmatterFormatter('toml');
+export const frontmatterTOML = customDelimiter => new FrontmatterFormatter('toml', customDelimiter);
-export const FrontmatterJSON = new FrontmatterFormatter('json');
+export const frontmatterJSON = customDelimiter => new FrontmatterFormatter('json', customDelimiter);

src/reducers/collections.js

@@ -4,7 +4,7 @@ import consoleError from 'Lib/consoleError';
 import { CONFIG_SUCCESS } from 'Actions/config';
 import { FILES, FOLDER } from 'Constants/collectionTypes';
 import { INFERABLE_FIELDS } from 'Constants/fieldInference';
-import { formatByExtension, formatToExtension, supportedFormats } from 'Formats/formats';
+import { formatByExtension, formatToExtension, supportedFormats, frontmatterFormats } from 'Formats/formats';
 
 const collections = (state = null, action) => {
   const configCollections = action.payload && action.payload.collections;
@@ -38,6 +38,11 @@ function validateCollection(configCollection) {
     // Cannot infer format from extension.
     throw new Error(`Please set a format for collection "${ collectionName }". Supported formats are ${ supportedFormats.join(',') }`);
   }
+  if (has(configCollection, 'frontmatter_delimiter') && !frontmatterFormats.includes(get(configCollection, 'format'))) {
+    // Cannot set custom delimiter without explicit and proper frontmatter format declaration
+    throw new Error(`Please set a proper frontmatter format for collection "${ collectionName }" to use a custom delimiter. Supported frontmatter formats are yaml-frontmatter, toml-frontmatter, and json-frontmatter.`);
+  }
+
 }
 
 const selectors = {

website/site/content/docs/configuration-options.md

@@ -77,6 +77,7 @@ The `collections` setting is the heart of your Netlify CMS configuration, as it
 - `delete`: `false` prevents users from deleting items in a collection; defaults to `true`
 - `extension`: see detailed description below
 - `format`: see detailed description below
+- `frontmatter_delimiter`: see detailed description under `format`
 - `slug`: see detailed description below
 - `fields` (required): see detailed description below
 
@@ -96,11 +97,11 @@ You may also specify a custom `extension` not included in the list above, as lon
 - `toml`: parses and saves files as TOML-formatted data files; saves with `toml` extension by default
 - `json`: parses and saves files as JSON-formatted data files; saves with `json` extension by default
 - `frontmatter`: parses files and saves files with data frontmatter followed by an unparsed body text (edited using a `body` field); saves with `md` extension by default; default for collections that can't be inferred. Collections with `frontmatter` format (either inferred or explicitly set) can parse files with frontmatter in YAML, TOML, or JSON format. However, they will be saved with YAML frontmatter.
-- `yaml-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved only as YAML, followed by unparsed body text
+- `yaml-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved only as YAML, followed by unparsed body text. The default delimiter for this option is  `---`.
-- `toml-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved only as TOML, followed by unparsed body text
+- `toml-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved only as TOML, followed by unparsed body text. The default delimiter for this option is  `+++`.
-- `json-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved as JSON, followed by unparsed body text
+- `json-frontmatter`: same as the `frontmatter` format above, except frontmatter will be both parsed and saved as JSON, followed by unparsed body text. The default delimiter for this option is  `{` `}`.
 
-The explicit `yaml-frontmatter`, `toml-frontmatter`, and `json-frontmatter` formats above do not currently support custom delimiters. We use `---` for YAML, `+++` for TOML, and `{` `}` for JSON. If a file has frontmatter inside other delimiters it will be included as part of the body text.
+`frontmatter_delimiter`: if you have an explicit frontmatter format declared, this option allows you to specify a custom delimiter like `~~~`.
 
 
 ### `slug`