Use more than 2 arguments in concat method (#72)

* concat function with more than 2 argumnets

* 2.6.11

Author: kbarbounakis

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@themost/sqlite",
-  "version": "2.6.10",
+  "version": "2.6.11",
   "description": "MOST Web Framework SQLite Adapter",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

package.json

@@ -1,3 +1,4 @@
+import { QueryField } from '@themost/query';
 import { TestApplication } from './TestApplication';
 
 describe('StringFunctions', () => {
@@ -41,6 +42,25 @@ describe('StringFunctions', () => {
         });
     });
 
+    it('should use concat()', async () => {
+        await app.executeInTestTranscaction(async (context) => {
+            let items = await context.model('Product')
+                .select(new QueryField('id'), new QueryField({
+                    name: {
+                        $concat: [
+                            new QueryField('name'),
+                            '-',
+                            new QueryField('model')
+                        ]
+                    }
+                })).where('name').startsWith('Apple').equal(true).getItems();
+            expect(items).toBeInstanceOf(Array);
+            for (const item of items) {
+                expect(item.name.startsWith('Apple')).toBeTruthy();
+            }
+        });
+    });
+
     it('should use lower()', async () => {
         await app.executeInTestTranscaction(async (context) => {
             let items = await context.model('Product')

spec/StringFunctions.spec.js

@@ -136,8 +136,18 @@ class SqliteFormatter extends SqlFormatter {
      * @param {*} p1
      * @returns {string}
      */
+    // eslint-disable-next-line no-unused-vars
     $concat(p0, p1) {
-        return sprintf('(IFNULL(%s,\'\') || IFNULL(%s,\'\'))', this.escape(p0), this.escape(p1));
+        const args = Array.from(arguments);
+        if (args.length < 2) {
+            throw new Error('Concat method expects two or more arguments');
+        }
+        let result = '(';
+        result += Array.from(args).map((arg) => {
+            return `IFNULL(${this.escape(arg)},\'\')`
+        }).join(' || ');
+        result += ')';
+        return result;
     }
     /**
      * Implements substring(str,pos) expression formatter.