Added ORDER BY mixin

.prettierrc

+{
+  "singleQuote": true,
+  "tabWidth": 2,
+  "useTabs": false,
+  "printWidth": 80
+}

package.json

@@ -19,8 +19,8 @@
   "author": "Milan Wikarski,Marcel Odumorek",
   "license": "ISC",
   "dependencies": {
-    "pg": "^7.8.2",
-    "@creanet/js-type": "1.0.0"
+    "@creanet/js-type": "^1.2.0",
+    "pg": "^7.8.2"
   },
   "devDependencies": {
     "dotenv": "^8.2.0"

src/classes/insert.class.js

+const { is } = require('@creanet/js-type');
 const SpecificQuery = require('./query.specific.class');
 const { ValuesMixin } = require('../mixins');
 
 class Insert extends ValuesMixin(SpecificQuery) {
   get canExecute() {
-    return this._values != null;
+    return !is.null(this._values);
   }
 
   get query() {

src/classes/query.class.js

 /** @typedef {import('../database.class.js') Database} */
 
+const { is } = require('@creanet/js-type');
+
 class Query {
   /**
    * Creates an instance of Query.
@@ -34,7 +36,7 @@ class Query {
    * @readonly
    */
   get canExecute() {
-    return this.query != '';
+    return !is.emptyString(this.query);
   }
 
   /**

src/classes/select.class.js

+const { is } = require('@creanet/js-type');
 const SpecificQuery = require('./query.specific.class');
 const {
   ColumnsMixin,
   LimitMixin,
   OffsetMixin,
-  WhereMixin
+  WhereMixin,
+  OrderByMixin
 } = require('../mixins');
 
 class Select extends WhereMixin(
-  OffsetMixin(LimitMixin(ColumnsMixin(SpecificQuery)))
+  OrderByMixin(OffsetMixin(LimitMixin(ColumnsMixin(SpecificQuery))))
 ) {
   get canExecute() {
-    return this._columns != null;
+    return !is.null(this._columns);
   }
 
   get query() {
-    return `SELECT ${this.columnsSQL} FROM ${this.table} ${this.whereSQL} ${this.limitSQL} ${this.offsetSQL}`;
+    return `SELECT ${this.columnsSQL} FROM ${this.table} ${this.whereSQL} ${this.orderBySQL} ${this.limitSQL} ${this.offsetSQL}`;
   }
 }
 

src/mixins/columns.mixin.js

-const is = require('@creanet/js-type');
+const { is, force } = require('@creanet/js-type');
 
 const ColumnsMixin = C =>
   class ColumnsMixin extends C {
@@ -8,10 +8,6 @@ const ColumnsMixin = C =>
     }
 
     get columnsSQL() {
-      if (is.string(this._columns)) {
-        return this._columns;
-      }
-
       return this._columns.join(',');
     }
 
@@ -24,8 +20,11 @@ const ColumnsMixin = C =>
      * @param {string|string[]} columns
      */
     columns(columns) {
-      if (!is(columns, ['string', 'array']))
+      columns = force.array(columns);
+
+      if (!is.array(columns, 'string')) {
         throw TypeError('columns is of invalid type');
+      }
 
       this._columns = columns;
 

src/mixins/index.js

@@ -3,5 +3,6 @@ module.exports = {
   LimitMixin: require('./limit.mixin'),
   OffsetMixin: require('./offset.mixin'),
   ValuesMixin: require('./values.mixin'),
-  WhereMixin: require('./where.mixin')
+  WhereMixin: require('./where.mixin'),
+  OrderByMixin: require('./order-by.mixin')
 };

src/mixins/limit.mixin.js

-const is = require('@creanet/js-type');
+const { is } = require('@creanet/js-type');
 
 const LimitMixin = C =>
   class LimitMixin extends C {
@@ -8,7 +8,7 @@ const LimitMixin = C =>
     }
 
     get limitSQL() {
-      if (this._limit == null) {
+      if (is.null(this._limit)) {
         return '';
       }
 
@@ -22,7 +22,9 @@ const LimitMixin = C =>
      * @param {number} limit
      */
     limit(limit) {
-      if (!is(limit, 'numeric')) throw TypeError('limit is of invalid type');
+      if (!is.numeric(limit)) {
+        throw TypeError('limit is of invalid type');
+      }
 
       this._limit = limit;
 

src/mixins/offset.mixin.js

-const is = require('@creanet/js-type');
+const { is } = require('@creanet/js-type');
 
 const OffsetMixin = C =>
   class OffsetMixin extends C {
@@ -8,7 +8,7 @@ const OffsetMixin = C =>
     }
 
     get offsetSQL() {
-      if (this._offset == null) {
+      if (is.null(this._offset)) {
         return '';
       }
 
@@ -22,7 +22,9 @@ const OffsetMixin = C =>
      * @param {number} offset
      */
     offset(offset) {
-      if (!is(offset, 'numeric')) throw TypeError('offset is of invalid type');
+      if (!is.numeric(offset)) {
+        throw TypeError('offset is of invalid type');
+      }
 
       this._offset = offset;
 

src/mixins/order-by.mixin.js

+const { is, force } = require('@creanet/js-type');
+
+const OrderByMixin = C =>
+  class OrderByMixin extends C {
+    constructor() {
+      super(...arguments);
+      this._orderBy = null;
+    }
+
+    get orderBySQL() {
+      if (is.null(this._orderBy)) {
+        return '';
+      }
+
+      // This assumes Object.entries(obj).length === 2
+      const orderBy = this._orderBy
+        .map(obj => Object.entries(obj)[0].join(' '))
+        .join(',');
+
+      return `ORDER BY ${orderBy}`;
+    }
+
+    orderBy(orderBy) {
+      orderBy = force.array(orderBy);
+
+      if (!is.array(orderBy, 'keyValuePair')) {
+        throw TypeError('orderBy is of invalid type');
+      }
+
+      this._orderBy = orderBy;
+
+      return this;
+    }
+  };
+
+module.exports = OrderByMixin;

src/mixins/values.mixin.js

-const is = require('@creanet/js-type');
+const { is, force } = require('@creanet/js-type');
 
 const ValuesMixin = C =>
   class ValuesMixin extends C {
@@ -22,14 +22,13 @@ const ValuesMixin = C =>
      * - `{Object}` - one record with key:value pairs
      * - `{Array<Object>} - multiple records
      *
-     * @param {Array<Object>} values
+     * @param {Object|Array<Object>} values
      */
     values(values) {
-      if (!is(values, ['array', 'object']))
-        throw new TypeError('values is of invalid type');
+      values = force.array(values);
 
-      if (!is.array(values)) {
-        values = [values];
+      if (!is.array(values, 'object')) {
+        throw new TypeError('values is of invalid type');
       }
 
       this._values = values;

src/mixins/where.mixin.js

-const is = require('@creanet/js-type');
+const { is } = require('@creanet/js-type');
 
 const WhereMixin = C =>
   class WhereMixin extends C {
@@ -8,7 +8,7 @@ const WhereMixin = C =>
     }
 
     get whereSQL() {
-      if (this._where == null) {
+      if (is.null(this._where)) {
         return '';
       }
 

tests/test.js

@@ -11,7 +11,13 @@ const db = new DB({
 
 const select = async () => {
   console.log('SELECT');
-  const select = db.select('lorem').columns('*');
+  const select = db
+    .select('lorem')
+    .columns('*')
+    .orderBy({ id: 'DESC' })
+    .where(`"id" != '2'`)
+    .limit(1)
+    .offset(1);
 
   console.log(select.query);
   if (await select.execute()) {