feat: use resolveJsonModule to load datasource config

Enable TypeScript feature "resolveJsonModule" to load datasource
configurations in a type-safe way using regular "import" statements.

Author: bajtos

docs/site/Repositories.md

@@ -326,7 +326,7 @@ context.
 ```ts
 import {inject} from '@loopback/core';
 import {juggler, AnyObject} from '@loopback/repository';
-const config = require('./redis.datasource.json');
+import * as config from './redis.datasource.json';
 
 export class RedisDataSource extends juggler.DataSource {
   static dataSourceName = 'redis';

docs/site/Testing-your-application.md

@@ -652,8 +652,7 @@ instance:
 
 ```ts
 import {merge} from 'lodash';
-
-const GEO_CODER_CONFIG = require('../src/datasources/geo.datasource.json');
+import * as GEO_CODER_CONFIG from '../src/datasources/geo.datasource.json';
 
 function givenGeoService() {
   const config = merge({}, GEO_CODER_CONFIG, {

examples/soap-calculator/src/datasources/calculator.datasource.ts

@@ -1,13 +1,13 @@
 import {inject} from '@loopback/core';
-import {juggler, AnyObject} from '@loopback/repository';
-const config = require('./calculator.datasource.json');
+import {juggler} from '@loopback/repository';
+import * as config from './calculator.datasource.json';
 
 export class CalculatorDataSource extends juggler.DataSource {
   static dataSourceName = 'calculator';
 
   constructor(
     @inject('datasources.config.calculator', {optional: true})
-    dsConfig: AnyObject = config,
+    dsConfig: object = config,
   ) {
     dsConfig = Object.assign({}, dsConfig, {
       // A workaround for the current design flaw where inside our monorepo,

examples/todo-list/src/datasources/db.datasource.ts

@@ -4,15 +4,15 @@
 // License text available at https://opensource.org/licenses/MIT
 
 import {inject} from '@loopback/core';
-import {juggler, DataSource} from '@loopback/repository';
-const config = require('./db.datasource.json');
+import {juggler} from '@loopback/repository';
+import * as config from './db.datasource.json';
 
 export class DbDataSource extends juggler.DataSource {
   static dataSourceName = 'db';
 
   constructor(
     @inject('datasources.config.db', {optional: true})
-    dsConfig: DataSource = config,
+    dsConfig: object = config,
   ) {
     super(dsConfig);
   }

examples/todo/src/datasources/db.datasource.ts

@@ -4,15 +4,15 @@
 // License text available at https://opensource.org/licenses/MIT
 
 import {inject} from '@loopback/core';
-import {juggler, DataSource} from '@loopback/repository';
-const config = require('./db.datasource.json');
+import {juggler} from '@loopback/repository';
+import * as config from './db.datasource.json';
 
 export class DbDataSource extends juggler.DataSource {
   static dataSourceName = 'db';
 
   constructor(
     @inject('datasources.config.db', {optional: true})
-    dsConfig: DataSource = config,
+    dsConfig: object = config,
   ) {
     super(dsConfig);
   }

examples/todo/src/datasources/geocoder.datasource.ts

@@ -5,7 +5,7 @@
 
 import {inject} from '@loopback/core';
 import {juggler, AnyObject} from '@loopback/repository';
-const config = require('./geocoder.datasource.json');
+import * as config from './geocoder.datasource.json';
 
 export class GeocoderDataSource extends juggler.DataSource {
   static dataSourceName = 'geocoder';

examples/todo/test/helpers.ts

@@ -8,6 +8,7 @@ import {merge} from 'lodash';
 import * as path from 'path';
 import {Todo} from '../src/models/index';
 import {GeoPoint} from '../src/services/geocoder.service';
+import * as GEO_CODER_CONFIG from '../src/datasources/geocoder.datasource.json';
 
 /*
  ==============================================================================
@@ -54,8 +55,6 @@ export const aLocation = {
   },
 };
 
-const GEO_CODER_CONFIG = require('../src/datasources/geocoder.datasource.json');
-
 export function getProxiedGeoCoderConfig(proxy: HttpCachingProxy) {
   return merge({}, GEO_CODER_CONFIG, {
     options: {

packages/build/config/tsconfig.common.json

@@ -5,6 +5,7 @@
     "experimentalDecorators": true,
     "noImplicitAny": true,
     "strictNullChecks": true,
+    "resolveJsonModule": true,
 
     "lib": ["es2018", "dom", "esnext.asynciterable"],
     "module": "commonjs",

packages/cli/generators/datasource/templates/datasource.ts.ejs

@@ -1,13 +1,13 @@
 import {inject} from '@loopback/core';
-import {juggler, AnyObject} from '@loopback/repository';
-const config = require('./<%= jsonFileName %>');
+import {juggler} from '@loopback/repository';
+import * as config from './<%= jsonFileName %>';
 
 export class <%= className %>DataSource extends juggler.DataSource {
   static dataSourceName = '<%= name %>';
 
   constructor(
     @inject('datasources.config.<%= name %>', {optional: true})
-    dsConfig: AnyObject = config,
+    dsConfig: object = config,
   ) {
     super(dsConfig);
   }

packages/cli/test/integration/generators/datasource.integration.js

@@ -163,11 +163,11 @@ function checkBasicDataSourceFiles() {
   assert.fileContent(expectedTSFile, /import {inject} from '@loopback\/core';/);
   assert.fileContent(
     expectedTSFile,
-    /import {juggler, AnyObject} from '@loopback\/repository';/,
+    /import {juggler} from '@loopback\/repository';/,
   );
   assert.fileContent(
     expectedTSFile,
-    /const config = require\('.\/ds.datasource.json'\)/,
+    /import \* as config from '.\/ds.datasource.json';/,
   );
   assert.fileContent(
     expectedTSFile,