feat(gatsby-source-drupal): Add toggleable multilingual support by prefixing nodes with their langcode (#26720)

* Determine languages from JSON:API content, use languages to fetch translations if 'translations' param provided

* Sort configurable languages by weight to retrieve default

* Fix lint issues

* Allow for more than 50 configurable_language and language_content_settings entities

* Default to und language if no langcode is provided by node

* Add await to promises.
Assign concats to the original variables.
Fix deleteNode to use langcodes
Fix for default languages url building

* fix: extract href from link objects when fetching translation settings

* refactor: use getHref in gatsby-source-drupal when possible

* Update gatsby-node.js

* Update normalize.js

* Update normalize.js

* Update gatsby-node.js

* Update gatsby-node.js

Avoid silently failing to fetch enabled language from Drupal

* Update gatsby-node.js

* Fix lint issues

* Update utils.js

* Update utils.js

* Remove dependence on languageConfig from handleReferences

* Fix lint

* fix id creation

* If translation is not enabled, always use  for langcode

* Catch and report error in multilingual not enabled in Drupal + ensure all langcode still

* The default language JSONAPI root doesn't include its language code

* Use url-join + check for non-default langauges

* Use urlJoin more

* update yarn.lock

* update tests"

* Remove dynamically fetching language config

Instead set the config in the plugin options e.g.:

```js
options: {
  translation: true,
  languageConfig: {
    defaultLanguage: `en`,
    enabledLanguages: [`en`, `fil`],
    translatableEntities: [`node--article`],
  }
}
```

* remove import

* Remove mistakenly committed file and ignore it

* Add docs & just use existance of languageConfig to determine if translations are enabled or not

* Fix check

Co-authored-by: Hannes Vermeire <[email protected]>
Co-authored-by: Błażej Owczarczyk <[email protected]>
Co-authored-by: nbaosullivan <[email protected]>
Co-authored-by: Kyle Mathews <[email protected]>

Author: 5 people

packages/gatsby-source-drupal/.gitignore

@@ -1,3 +1,4 @@
 /gatsby-node.js
 /normalize.js
 /utils.js
+/plugin-options.js

packages/gatsby-source-drupal/README.md

@@ -292,6 +292,29 @@ module.exports = {
 }
 ```
 
+## Translations
+
+If you have translations or multilingual enabled on your Drupal site, you can opt-in to sourcing translations of entities. To do this, enable in your plugin's configuration the languages and entity types you'd like to source. E.g.
+
+```javascript
+// In your gatsby-config.js
+module.exports = {
+  plugins: [
+    {
+      resolve: `gatsby-source-drupal`,
+      options: {
+        baseUrl: `https://live-contentacms.pantheonsite.io/`,
+        languageConfig: {
+          defaultLanguage: `en`,
+          enabledLanguages: [`en`, `fil`],
+          translatableEntities: [`node--article`],
+        },
+      },
+    },
+  ],
+}
+```
+
 ## Gatsby Preview (experimental)
 
 You will need to have the Drupal module installed, more information on that here: https://www.drupal.org/project/gatsby

packages/gatsby-source-drupal/package.json

@@ -13,7 +13,8 @@
     "body-parser": "^1.19.0",
     "gatsby-source-filesystem": "^3.6.0-next.0",
     "lodash": "^4.17.21",
-    "tiny-async-pool": "^1.2.0"
+    "tiny-async-pool": "^1.2.0",
+    "url-join": "^4.0.1"
   },
   "devDependencies": {
     "@babel/cli": "^7.12.1",
@@ -22,11 +23,7 @@
     "cross-env": "^7.0.3"
   },
   "homepage": "https://github.com/gatsbyjs/gatsby/tree/master/packages/gatsby-source-drupal#readme",
-  "keywords": [
-    "gatsby",
-    "gatsby-plugin",
-    "gatsby-source-plugin"
-  ],
+  "keywords": ["gatsby", "gatsby-plugin", "gatsby-source-plugin"],
   "license": "MIT",
   "peerDependencies": {
     "gatsby": "^3.0.0-next.0"