dev: add database and config access for extensions

src/backend/src/CoreModule.js

@@ -64,6 +64,7 @@ const install = async ({ services, app, useapi, modapi }) => {
         def('core.APIError', require('./api/APIError'));
         
         def('core', require('./services/auth/Actor'), { assign: true });
+        def('core.config', config);
     });
     
     // === LIBRARIES ===

src/backend/src/Extension.js

@@ -20,6 +20,21 @@ class Extension extends AdvancedBase {
         this.ensure_service_();
     }
 
+    example () {
+        console.log('Example method called by an extension.');
+    }
+
+    get db () {
+        const db = this.service.values.get('db');
+        if ( ! db ) {
+            throw new Error(
+                'extension tried to access database before it was ' +
+                'initialized'
+            );
+        }
+        return db;
+    }
+
     get (path, handler, options) {
         // this extension will have a default service
         this.ensure_service_();

src/backend/src/ExtensionService.js

@@ -2,6 +2,8 @@ const { AdvancedBase } = require("@heyputer/putility");
 const BaseService = require("./services/BaseService");
 const { Endpoint } = require("./util/expressutil");
 const configurable_auth = require("./middleware/configurable_auth");
+const { Context } = require("./util/context");
+const { DB_READ, DB_WRITE } = require("./services/database/consts");
 
 class ExtensionServiceState extends AdvancedBase {
     constructor (...a) {
@@ -10,6 +12,9 @@ class ExtensionServiceState extends AdvancedBase {
         this.extension = a[0].extension;
 
         this.endpoints_ = [];
+        
+        // Values shared between the `extension` global and its service
+        this.values = new Context();
     }
     register_route_handler_ (path, handler, options = {}) {
         // handler and options may be flipped
@@ -51,6 +56,10 @@ class ExtensionService extends BaseService {
     async _init (args) {
         this.state = args.state;
 
+        // Create database access object for extension
+        const db = this.services.get('database').get(DB_WRITE, 'extension');
+        this.state.values.set('db', db);
+
         // Propagate all events not from extensions to `core.`
         const svc_event = this.services.get('event');
         svc_event.on_all((key, data, meta = {}) => {