title: How to Create DropdownButton with a list of JSON Data and I want it to populate my DropDownButton in Flutter
body: <p>The Data Will be like this</p>
  
  <pre><code>[{ID: 1, Code: 01, Description: REGION I (ILOCOS REGION), PSGCCode: 010000000}, {ID: 2, Code: 02, Description: REGION II (CAGAYAN VALLEY), PSGCCode: 020000000},
  </code></pre>
  
  <p>and I only want to use the Description as the text in the DropDownButton </p>
  
  <p>EDIT****</p>
  
  <p>Does the Class looks like this?</p>
  
  <pre><code>class Region {
  
    final int regionid;
    final String regionDescription;
  
    Region ({
      this.regionid,
      this.regionDescription
    }); 
    factory Region.fromJson(Map&lt;String, dynamic&gt; json) {
  
      return new Region(
        regionid: json['id'],
        regionDescription: json['description']
  
      );
    }
  }
  </code></pre>
  
  <p>EDIT** Tried To Use or Do the Class above and Assign it to a List </p>
  
  <pre><code>List&lt;Region&gt; _region = [];
  </code></pre>
  
  <p>and Use it for my DropDownItems</p>
  
  <hr>
  
  <pre><code> child: new DropdownButtonHideUnderline(
                  child: new DropdownButton&lt;String&gt;(
                    hint: new Text("Select Region"),
                    value: selectedRegion,
                    isDense: true,
                    onChanged: (String newValue) {
                      setState(() {
                        selectedRegion = newValue;
                      });
                      print(selectedRegion);
                    },
  items: _region.map((Region map) {
                          return new DropdownMenuItem&lt;String&gt;(
                            value: map.regionDescription,
                            child: new Text(map.regionDescription,
                                style: new TextStyle(color: Colors.black)),
                          );
                        }).toList(),
  </code></pre>
  
  <p>And an Exception is Caught every time itried to tap DropdownButton</p>
  
  <pre><code>I/flutter (11272): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
  I/flutter (11272): The following ArgumentError was thrown during paint():
  I/flutter (11272): Invalid argument(s): 0.0
  I/flutter (11272): When the exception was thrown, this was the stack:
  I/flutter (11272): #0      double.clamp (dart:core/runtime/libdouble.dart:143:7)
  I/flutter (11272): #1      _DropdownMenuPainter.paint (package:flutter/src/material/dropdown.dart:57:33)
  I/flutter (11272): #2      RenderCustomPaint._paintWithPainter (package:flutter/src/rendering/custom_paint.dart:520:13)
  I/flutter (11272): #3      RenderCustomPaint.paint (package:flutter/src/rendering/custom_paint.dart:558:7)
  I/flutter (11272): #4      RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:2018:7)
  I/flutter (11272): #5      PaintingContext.paintChild (package:flutter/src/rendering/object.dart:130:13)
  </code></pre>