Using custom hierarchical datasource

Support
#1

Hello, I need to use a treeTable with an entity, which has no parent property, but has children list… Maybe there is a common way to solve this problem? I guess it could be solved by a CustomHierarchicalDatasource, then could you, please, give a working sample of using custom hierarchical datasource? the one hosted on github is not working in local network without internet connection (i left an issue there)

#2

Hello,

Your case doesn’t feel like a huge programming problem.
Just copy the code of existing datasource (e.g. HierarchicalDatasourceImpl or CustomHierarchicalDatasource).
And replace all usages of:

Entity<K> parentItem = item.getValue(hierarchyPropertyName);

by this pseudo code:

Entity<K> parentItem = items.stream()
          .findFirst(p -> p.getChildren().contains(item))
          .orElse(null);

Example above is of course inefficient for large collections, so you might want to maintain an auxiliary data
structure to speed up parent lookup.

Regards,
Alexander.

1 Like
#3

let’s say i’m not so good at handling datasources to understand this pseudocode. could you, please, provide some more info? Also i didnt find any information about how to include a custom datasource to a screen, can you help me with that, please?

#4

A custom datasource is defined in the screen XML using the datasourceClass attribute of the datasource XML element. See the docs.

#5

thanks, maybe you could provide a sample with parent-to-child hierarchy? or better a sample for this one Showing a complex hierarchy - CUBA.Platform?

#6

You could at least try to save our time which you want us to spend for solving your problem by providing a test project with data model and screens.

#7

Parent-Children.zip (92.8 KB)

I created a tree, but can’t properly handle datasources in it… it asks for a view in a treenode datasource, i guess… anyhow it can’t handle different amounts fo kids in a parent((

#8

I tried to understand the data model in your sample but I failed.
You wrote " I need to use a treeTable with an entity, which has no parent property, but has children list… " but in your project the entity has two lists: parents and children. What does it mean and how do you want to present it?

#9

sorry for bothering, i did it by myself, creating a virtual tree. my question was an attemt to understand - is there a known easy way to implement something like complex hierarchy with a many-to-many connection through another entity. Once again sorry