Goal

The goal is to allow actions to act over more than one item, e.g. deleting multiple items at once etc. 

The restriction is to make it possible with minimal intervention to the current API.

Jira issue:  MGNLUI-1515 - Getting issue details... STATUS

Considerations

• most of the actions will remain single-item restricted;
• multi-item actions are to be used (mostly) in the workbench;
• neither Action nor ActionDefinition interfaces specify anything about the items passed to the action - it's all done in the action's constructor;
• the ActionExecutor interface already expects multiple items in the isAvailable(String actionName, Item... items) method, and virtually also in the execute(String actionName, Object... args) method;

Proposal

Next: 5.1

The action availability described in the Concept - Action availability and access control will be extended with an availability.multiple property, set by default to false.

The AbstractActionExecutor.isAvailable() method will be changed to take the availability.multiple property into account in the availability evaluation (ATM it just returns false if the items.length is bigger than 1).

The BrowserPresenter.executeAction() method will be changed to pass the whole item list to the actionExecutor in such case, instead of just the first selected item. (There is already a TODO note with the above issue ID.)

The action is responsible to handle the items in a correct order, or solve the obvious dependencies (e.g. when deleting multiple nodes, where one node is a sub-node of the other one, delete them in a correct order to avoid exception, or handle such exception).

The action is responsible for informing the user about the result, i.e. whether it has successfully processed all the items, or failed on some of them. It is also responsible for the potential "transactional" processing, i.e. reverting all the items to the initial state, if the processing of one or more items fails. The recommended behaviour for most actions is "non-transactional" plus notifying the user about how many and which items couldn't be processed. The base support for this recommended behaviour will be implemented in new AbstractMultiItemAction class.

As an example (and a best-practices model), the DeleteItemAction will be made multi-item supporting.

Future

TODO - changes and enhancements after the 5.1 release