Implemented a reusable button, ascending & descending & allows for mu…

example/lib/main.dart

@@ -1,19 +1,14 @@
 import 'package:flutter/material.dart';
+import 'package:multi_sort/SortableButton.dart';
 import "package:multi_sort/multi_sort.dart";
 
 void main() {
   runApp(MyApp());
 }
 
 class MyApp extends StatelessWidget {
-  @override
   Widget build(BuildContext context) {
     return MaterialApp(
-      title: 'Flutter Demo',
-      theme: ThemeData(
-        primarySwatch: Colors.blue,
-        visualDensity: VisualDensity.adaptivePlatformDensity,
-      ),
       home: ExampleApp(),
     );
   }
@@ -22,82 +17,70 @@ class MyApp extends StatelessWidget {
 class ExampleApp extends StatefulWidget {
   ExampleApp({Key key}) : super(key: key);
 
-  @override
   _ExampleAppState createState() => _ExampleAppState();
 }
 
 /// Class of Items
-class Items {
+class Items implements Sortable {
   String name;
   int ram;
   int price;
   int storage;
   Items(this.name, this.ram, this.price, this.storage);
 
   ///Mapping the properties
-  Map<String, dynamic> _toMap() {
+  Map<String, Comparable> sortableFields() {
     return {'name': name, 'price': price, 'ram': ram, 'storage': storage};
   }
-
-  ///get function to get the properties of Item
-  dynamic get(String propertyName) {
-    var _mapRep = _toMap();
-    if (_mapRep.containsKey(propertyName)) {
-      return _mapRep[propertyName];
-    }
-    throw ArgumentError('propery not found');
-  }
 }
 
 class _ExampleAppState extends State<ExampleApp> {
   //List of Items
-  List<Items> items = [
-    Items("real me 6", 6, 18999, 128),
+  var data = [
+    Items("real me 6", 6, 18999, 1),
     Items("real me 6", 8, 19999, 128),
     Items("real Note 8", 7, 16999, 128),
-    Items("oppo a9", 4, 13999, 128),
+    Items("oppo a9", 4, 13999, 64),
     Items("real me 6 pro", 6, 17999, 64),
     Items("Oppo 5as", 2, 8999, 32),
     Items("Real me 5i", 4, 10999, 64),
     Items("Poco x2", 6, 18500, 128),
   ];
-  // Temp List for sorting
-  List<Items> sortingList = [];
-  //Criteria List
-  List<bool> criteria = [false, false];
-  //prefrrence List
-  List<String> preferrence = ['ram', 'storage'];
 
-  @override
-  void initState() {
-    // TODO: implement initState
-    super.initState();
+  var sortedFields = <SortField>[];
+
+  void setSortedFields(List<SortField> sortedFields) {
     setState(() {
-      sortingList = items;
+      this.sortedFields = sortedFields;
+      this.data = data.multisort(sortedFields);
     });
   }
 
-  @override
   Widget build(BuildContext context) {
     return Scaffold(
       appBar: AppBar(
         title: Text("Sort List Example"),
       ),
       body: Column(
         children: [
-          _buttons(),
+          Row(children: [
+            SortableButton(sortedFields, SortField('name'), setSortedFields),
+            SortableButton(sortedFields, SortField('price'), setSortedFields),
+            SortableButton(sortedFields, SortField('ram'), setSortedFields),
+            SortableButton(sortedFields, SortField('storage'), setSortedFields),
+          ]),
           ListView.builder(
               shrinkWrap: true,
-              itemCount: sortingList.length,
+              itemCount: data.length,
               itemBuilder: (BuildContext context, int i) {
                 return Card(
                   child: Row(
                     mainAxisAlignment: MainAxisAlignment.spaceBetween,
                     children: [
-                      Text(sortingList[i].name),
-                      Text(sortingList[i].price.toString()),
-                      Text(sortingList[i].ram.toString()),
-                      Text(sortingList[i].storage.toString()),
+                      Text(data[i].name),
+                      Text(data[i].price.toString()),
+                      Text(data[i].ram.toString()),
+                      Text(data[i].storage.toString()),
                     ],
                   ),
                 );
@@ -106,16 +89,4 @@ class _ExampleAppState extends State<ExampleApp> {
       ),
     );
   }
-
-  Widget _buttons() {
-    return RaisedButton(
-      onPressed: () {
-        setState(() {
-          ///Sorting using MultiSort
-          sortingList.multisort(criteria, preferrence);
-        });
-      },
-      child: Text('Sort by preferrence'),
-    );
-  }
 }

lib/SortableButton.dart

@@ -0,0 +1,74 @@
+import 'package:dartx/dartx.dart';
+import 'package:flutter/material.dart';
+import 'package:font_awesome_flutter/font_awesome_flutter.dart';
+
+import 'multi_sort.dart';
+
+/// A button to go with multi-sort to toggle sorting on multiple fields
+class SortableButton extends StatelessWidget {
+  /// The current list of sorted fields
+  final List<SortField> sortedFields;
+
+  /// This field
+  final SortField field;
+
+  /// The text for the button label
+  final String text;
+
+  /// A callback to set the altered sortedFields list
+  ///
+  /// '''void setSortedFields(List<SortField> sortedFields) {
+  //    setState(() {
+  //      this.sortedFields = sortedFields;
+  //      this.data = data.multisort(sortedFields);
+  //    });
+  //  }'''
+  final void Function(List<SortField>) onPressed;
+
+  SortableButton(this.sortedFields, this.field, this.onPressed, {this.text});
+
+  Widget build(BuildContext context) {
+    SortField thisSortedField;
+    int index;
+
+    sortedFields.forEachIndexed((e, i) {
+      if (e.fieldName == field.fieldName) {
+        index = i;
+        thisSortedField = e;
+      }
+    });
+
+    return TextButton(
+      onPressed: () {
+        var newSortedFields = <SortField>[];
+
+        if (thisSortedField == null) //
+          newSortedFields = [...sortedFields, field];
+        else {
+          if (thisSortedField.isAscending) //
+            newSortedFields = sortedFields.map((e) => e.fieldName != thisSortedField.fieldName ? e : SortField(e.fieldName, isAscending: false)).toList();
+          else
+            newSortedFields = sortedFields.where((e) => e.fieldName != thisSortedField.fieldName).toList();
+        }
+
+        onPressed(newSortedFields);
+      },
+      child: Row(
+        children: [
+          if (thisSortedField != null) //
+            ...[
+            Icon(
+              thisSortedField.isAscending ? FontAwesomeIcons.angleUp : FontAwesomeIcons.angleDown,
+              size: 15,
+            ),
+            Text(
+              index.toString(),
+              textScaleFactor: 0.6,
+            ),
+          ],
+          Text(this.text ?? field.fieldName),
+        ],
+      ),
+    );
+  }
+}

lib/multi_sort.dart

@@ -1,34 +1,60 @@
 library multi_sort;
 
-extension MultiSort on List {
-  multisort(List<bool> criteria, dynamic preferrence) {
-    if (preferrence.length == 0 || criteria.length == 0 || this.length == 0)
-      return this;
-    if (preferrence.length != criteria.length) {
-      print('Criteria length is not equal to preferrence');
+///get function to get the properties of Item
+Comparable getComparableField(String propertyName, Sortable sortable) {
+  var _mapRep = sortable.sortableFields();
+  if (_mapRep.containsKey(propertyName)) {
+    return _mapRep[propertyName];
+  }
+  throw ArgumentError('propery not found');
+}
+
+abstract class Sortable {
+  ///A list of strings and their textual ids eg
+  ///
+  /// {'name': name, 'price': price, 'ram': ram, 'storage': storage};
+  Map<String, Comparable> sortableFields();
+}
+
+class SortField {
+  final String fieldName;
+  final bool isAscending;
+
+  SortField(this.fieldName, {this.isAscending = true});
+}
+
+extension MultiSort on List<Sortable> {
+  List<Sortable> multisort(List<SortField> sortedFields) {
+    if (sortedFields.length == 0) //
       return this;
-    }
 
-    int compare(int i, dynamic a, dynamic b) {
-      if (a.get(preferrence[i]) == b.get(preferrence[i]))
-        return 0;
-      else if (a.get(preferrence[i]) > b.get(preferrence[i]))
-        return criteria[i] ? 1 : -1;
-      else
-        return criteria[i] ? -1 : 1;
+    int compare(int i, Sortable a, Sortable b) {
+      var valueA = getComparableField(sortedFields[i].fieldName, a);
+      var valueB = getComparableField(sortedFields[i].fieldName, b);
+
+      var result = valueA.compareTo(valueB);
+
+      if (!sortedFields[i].isAscending) //
+        return result * -1;
+
+      return result;
     }
 
     int sortall(a, b) {
       int i = 0;
       int result;
-      while (i < preferrence.length) {
+      while (i < sortedFields.length) {
         result = compare(i, a, b);
         if (result != 0) break;
         i++;
       }
       return result;
     }
 
-    this.sort((a, b) => sortall(a, b));
+    final list = this.toList();
+
+    list.sort((a, b) => sortall(a, b));
+
+    return list;
   }
 }

pubspec.yaml

@@ -10,6 +10,8 @@ environment:
 dependencies:
   flutter:
     sdk: flutter
+  dartx: ^0.6.0
+  font_awesome_flutter: ^9.0.0
 
 dev_dependencies:
   flutter_test:

test/multisort_test.dart

@@ -0,0 +1,82 @@
+//flutter test --plain-name=LessonSplitter
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:multi_sort/multi_sort.dart';
+
+/// Class of Items
+class Items implements Sortable {
+  String name;
+  int ram;
+  Items(this.name, this.ram);
+
+  String toString() => //
+      "name: ${this.name}, ram: ${this.ram}";
+
+  Map<String, Comparable> sortableFields() => //
+      {
+        'name': name,
+        'ram': ram,
+      };
+}
+
+void main() {
+  group("multiSort", () {
+//    List<Items> unsorted;
+
+    var unsorted = [
+      Items("b", 1),
+      Items("b", 128),
+      Items("a", 64),
+    ];
+
+//    setUp(() {
+//      unsorted = [
+//        Items("b", 1),
+//        Items("b", 128),
+//        Items("a", 64),
+//      ];
+//    });
+
+    test("two asc", () {
+      var sortedFields = [
+        SortField('ram'),
+        SortField('name'),
+      ];
+      var sorted = unsorted.multisort(sortedFields);
+      var expected = [
+        Items("b", 1),
+        Items("a", 64),
+        Items("b", 128),
+      ];
+
+      expect(sorted.toString(), expected.toString());
+    });
+
+    test("two asc & desc", () {
+      var sortedFields = [
+        SortField('name'),
+        SortField('ram', isAscending: false),
+      ];
+      var sorted = unsorted.multisort(sortedFields);
+      var expected = [
+        Items("a", 64),
+        Items("b", 128),
+        Items("b", 1),
+      ];
+
+      expect(sorted.toString(), expected.toString());
+    });
+
+    test("sort set to null", () {
+      var sortedFields = <SortField>[];
+      var sorted = unsorted.multisort(sortedFields);
+      var expected = [
+        Items("b", 1),
+        Items("b", 128),
+        Items("a", 64),
+      ];
+
+      expect(sorted.toString(), expected.toString());
+    });
+  });
+}