Vaadin 8 Tree with multiple dataProviders for hierarchical structure

Flow
1

I am using a tree to display different objects in hierarchical structure. Each element in the tree are of different object type and based on selection of the tree node i display different view in UI. Here is an example of Tree:-

* Connection1
 |_User1
    |_Environment1
	|_Environment2
* Connection2
  |_User2
    |_Environment3
	|_Environment4

Current Tree code allows only one dataProvider of specific object type.
How do I handle the about usecase, I dont want to convert these objects to string and display tree of string. What is the alternate approach? This is a basic tree usecase.

2

You will need a wrapper object in that case - something that contains a reference to the actual object, but allows you to specify just a single data type for the Tree. Either that or your data objects could implement a common interface.

-Olli

3

Olli Tietäväinen:
You will need a wrapper object in that case - something that contains a reference to the actual object, but allows you to specify just a single data type for the Tree. Either that or your data objects could implement a common interface.

-Olli

Thanks Olli for quick reply. Cant we not implement HierarchicalDataProvider?? and do //connectionTree.setDataProvider(new ConnectionTreeDataProvider()); and connectionTree.setData(connectionList);
Unfortunately, I am finding it hard to find good example for HierarchicalDataProvider. Appreciate if you could give me good example for this problem.

4

It’s not just about the DataProvider, I think you would need to reimplement the whole DataCommunicator mechanism too. I’m not saying it’s not possible, but you will have an easier time by using a wrapper.

5

Olli Tietäväinen:
You will need a wrapper object in that case - something that contains a reference to the actual object, but allows you to specify just a single data type for the Tree. Either that or your data objects could implement a common interface.

-Olli

Thank you for the solution, implemented a common interface for all objects in the tree and using single data provider I was able to get the tree loaded.

6

SDS SDS:

Olli Tietäväinen:
You will need a wrapper object in that case - something that contains a reference to the actual object, but allows you to specify just a single data type for the Tree. Either that or your data objects could implement a common interface.

-Olli

Thank you for the solution, implemented a common interface for all objects in the tree and using single data provider I was able to get the tree loaded.

I am trying to add multiple Connection on add new Connection Action. Should I reconstruct the tree data provider from Root node?? I am doing the below code

Collection<ABSWrapper> aliasList = AbsUI.get().getAliasManager().getABSWrapper();

		TreeData<ABSWrapper> data = new TreeData<>();
		// add root level items
		data.addItems(null, aliasList);

		for (ABSWrapper alias : aliasList) {

			User user = alias.getUser();
			data.addItem(alias, user);

			List<ABSWrapperEnvironment> userEnvList = user.getUserWrapperEnvList();

			for (ABSWrapperEnvironment absWrapperEnvironment : userEnvList) {
				data.addItem(user, absWrapperEnvironment);
			}

		}
		// construct the data provider for the hierarchical data we've built
		TreeDataProvider<ABSWrapper> dataProvider = new TreeDataProvider<>(data);

		connectionTree.setDataProvider(dataProvider);

However it is throwing java.lang.IllegalArgumentException: Cannot add the same item multiple times: user1
at com.vaadin.data.TreeData.addItem(TreeData.java:166)

How do i solve this problem?? Appreciate if you could provide links to examples or document which will help me solve these problems.

7

You will need to provide working equals and hashCode methods for your wrapper class; you can’t have identical objects in the hierarchy.