Make widgets backward compatible

The configuration of each ArcGIS Web AppBuilder widget is stored in the app. When a widget evolves with new functions, you need to modify the configuration format. To make the widget backward compatible with the previous configuration, you have two options: check the configuration format programmatically, or use VersionManager to upgrade the old format. The latter is strongly recommended due to the following advantages:

• The code is simpler, as it only processes the latest format.
• It is easier to track the changes, as they are put into one version manager file.
• The BaseVersionManager class can be inherited by completing the following steps:
  1. Add the “hasVersionManager” property to the widget manifest.json file, and set it to true.

     "properties": {
       	"hasVersionManager": true
       }

  2. Create a new file named VersionManager.js.

     define(['jimu/shared/BaseVersionManager'],
     function(BaseVersionManager) {
     
       function VersionManager(){
         this.versions = [{
           version: '1.0',
           upgrader: function(oldConfig){
             return oldConfig;
           }
         },{
           version: '1.1',
           upgrader: function(oldConfig){
             var newConfig = oldConfig;        
             return newConfig;
           }
         }];
       }
     
       VersionManager.prototype = new BaseVersionManager();
       VersionManager.prototype.constructor = VersionManager;
       return VersionManager;
     });

  When inheriting from the BaseVersionManager class, keep the following rules in mind:

  • Because BaseVersionManager runs in both the browser and Node.js, and Dojo classes are not imported into Node.js, any Dojo classes should not be used.
  • Put all your versions into the versions property.
  • For the upgrader function, the input is the old configuration and the output is the new configuration.