Flutter Dynamic Widget

You can dynamic update your flutter page with Flutter Dynamic Widget. It's a light json UI protocol, which is very similar with flutter widget code. So you don't need to learn another UI protocol, if you are familiar with flutter widget, you might already know how to write Flutter Dynamic Widget json.

Table of contents

General info

I work for an e-commerce company. We need to build flexible pages. So we define a light UI protocol, and implement on Android and iOS. We can dynamic update App UIs by pushing a json file. With this ability, we can do some UI A/B testing without publishing App to app store. Flutter allows you to build beautiful native apps on iOS and Android from a single codebase, it can allow you to build web app later. Flutter's hot reload helps you quickly and easily experiment, build UIs, add features, and fix bugs faster. But it still build native app, the UIs can't be dynamic updated. If you want to modify the UIs, you need to publish the updated app to app store. With this project, you can build your UIs from a json string, which is the UI protocal. The json string is very similar with the Flutter widget dart code. All widget type and widget properties are the same.

Widget type will be a type property, and widget's properties will be the json properties too. All properties and their values will be almost the same. You can checkout the following document.

Currently support flutter widgets and properties

Screenshots

Install

1. Depend on it

Add this to your package's pubspec.yaml file:

dependencies:
  dynamic_widget: ^0.0.1

2. Install it

You can install packages from the command line:

with Flutter:

$ flutter packages get

Alternatively, your editor might support flutter packages get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:dynamic_widget/dynamic_widget.dart';

Get started

You should use DynamicWidgetBuilder().build method to covert a json string into flutter widget. It will be time-consuming. so you'd better using FutureBuilder to build the UI.

import 'package:dynamic_widget/dynamic_widget.dart';
class PreviewPage extends StatelessWidget{

  final String jsonString;

  PreviewPage(this.jsonString);


  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          // Here we take the value from the MyHomePage object that was created by
          // the App.build method, and use it to set our appbar title.
          title: Text("Preview"),
        ),
        body: FutureBuilder<Widget>(
          future: _buildWidget(),
          builder: (BuildContext context, AsyncSnapshot<Widget> snapshot){
            return snapshot.hasData?snapshot.data:Text("Loading...");
          },
        ),
    );
  }

  Future<Widget> _buildWidget() async{

    return DynamicWidgetBuilder().build(jsonString, null);
  }
}

How to implement a WidgetParser

  1. You need to implement the WidgetParser abstract class.
  2. Add new created WidgetParser to DynamicWidgetBuilder.parsers list.

This is a RaisedButton widget parser.

import 'package:dynamic_widget/dynamic_widget/utils.dart';
import 'package:dynamic_widget/dynamic_widget.dart';
import 'package:flutter/material.dart';

class RaisedButtonParser extends WidgetParser{
  @override
  bool forWidget(String widgetName) {
    return "RaisedButton" == widgetName;
  }

  @override
  Widget parse(Map<String, dynamic> map) {
    return RaisedButton(
      color: map.containsKey('color') ? parseHexColor(map['color']) : null,
      disabledColor: map.containsKey('disabledColor') ? parseHexColor(map['disabledColor']) : null,
      disabledElevation: map.containsKey('disabledElevation') ? map['disabledElevation'] : 0.0,
      disabledTextColor: map.containsKey('disabledTextColor') ? parseHexColor(map['disabledTextColor']) : null,
      elevation: map.containsKey('elevation') ? map['elevation'] : 0.0,
      padding: map.containsKey('padding') ? parseEdgeInsetsGeometry(map['padding']) : null,
      splashColor : map.containsKey('splashColor') ? parseHexColor(map['splashColor']) : null,
      textColor: map.containsKey('textColor') ? parseHexColor(map['textColor']) : null,
      child: DynamicWidgetBuilder().buildFromMap(map['child']),
      onPressed: (){},
    );
  }

}

Add it to parsers list.

class DynamicWidgetBuilder{

  final Logger log = Logger('DynamicWidget');

  static final parsers = [
    ContainerWidgetParser(),
    TextWidgetParser(),
    RaisedButtonParser(),
    RowWidgetParser()
  ];


  Widget build(String json){

    var map = jsonDecode(json);
    return buildFromMap(map);
  }

  Widget buildFromMap(Map<String, dynamic> map){
    String widgetName = map['type'];

    for (var parser in parsers) {
      if (parser.forWidget(widgetName)) {
        return parser.parse(map);
      }
    }

    log.warning("Not support type: $widgetName");
    return null;
  }

  List<Widget> buildWidgets(List<dynamic> values){
    List<Widget> rt = [];
    for (var value in values) {
      rt.add(buildFromMap(value));
    }
    return rt;
  }
}

How to add a click listener

Add "click_event" property to your widget json definition. for example:

var raisedButton_json =
'''
{
  "type": "Container",
  "alignment": "center",
  "child": {
    "type": "RaisedButton",
    "color": "##FF00FF",
    "padding": "8,8,8,8",
    "textColor": "#00FF00",
    "elevation" : 8.0,
    "splashColor" : "#00FF00",
    "click_event" : "route://productDetail?goods_id=123",
    "child" : {
      "type": "Text",
      "data": "I am a button"
    }  
  }
}

We suggest you'd better to use an URI to define the event, as the exmaple, it's a event for going to a product detail page.

Then, define a ClickListener

class DefaultClickListener implements ClickListener{
  @override
  void onClicked(String event) {
    print("Receive click event: " + event);
  }

}

Finally, pass the listener to build method.

  Future<Widget> _buildWidget() async{

    return DynamicWidgetBuilder().build(jsonString, new DefaultClickListener());
  }

Documents

Currently support widgets and properties

Setup

Checkout this project and run deom.

Code Examples

Checkout this project and run deom.

Features

Already completed widgets:

  • Container
  • Text & TextSpan
  • Row & Column
  • AssetImage
  • NetworkImage
  • FileImage
  • Placeholder
  • GridView
  • ListView
  • PageView
  • Expanded
  • Padding
  • Center
  • Align
  • AspectRatio
  • FittedBox
  • Baseline
  • Stack
  • Positioned
  • IndexedStack
  • ExpandedSizedBox
  • SizedBox

You can view Currently support widgets and properties here.

Contact

Created by @deng.yin@gmail.com - feel free to contact me!

Libraries

align_widget_parser
aspectratio_widget_parser
baseline_widget_parser
button_widget_parser
center_widget_parser
container_widget_parser
dynamic_widget
expanded_widget_parser
fittedbox_widget_parser
gridview_widget_parser
image_widget_parser
indexedstack_widget_parser
listview_widget_parser
opacity_widget_parser
padding_widget_parser
pageview_widget_parser
placeholder_widget_parser
row_column_widget_parser
sizedbox_widget_parser
stack_positioned_widgets_parser
text_widget_parser
utils
wrap_widget_parser