What are the limitation in VRO with using a predefined list of elements in your presentation?

[improvingdaily]

I have done some limited testing and noticed a major difference when I select to "select value as" and specify list vs. using a predefined list of elements and selecting an action that gets the same list.  In my case I am trying to select a VM.  When I specify to select values as list I noticed that the list is empty when it first comes up and you either have to press a space or something in the filter box to find the system you are looking for.  I thought I might be able to fix this by using a predefined list of elements and linking it to the action getAllVMs.  When I do this it take a long time for my presentation to even come up and when I go to select a VM I am not even presented a list view.  It presents a tree.  I think I must be at the limit of the array however I am not sure what that limit is.  I also prefer to use the list format vs the other options.  Any suggestions for best practices when displaying and searching large lists? 

[iiliev]

Hi,

When you use 'predefined list of elements' bound to an action, the action code may gets called multiple times before the presentation comes up, which could take a lot of time, especially with actions that are inherently slow (like enumerating and returning all VMs in a vCenter).

Usually, when you want to use an object selector with potentially huge number of objects, it is better either to use tree chooser instead of list chooser, or filter the list to reduce the number of objects to choose from.

For getAllVMs results presented as a tree instead of list - I'm not sure why. Which vRO version is this?

[improvingdaily]

This is actually VCO version 5.5.  So it should be faster if I run a action to filter my results before I present them in a predefined list of elements?

[iiliev · Accepted solution]

It should be faster if the action bound to 'predefined list of elements' presentation property is not getAllVMs (which is a very slow action) but your custom action with return type Array/VC:VirtualMachine that returns a small set of virtual machines, eg. returns the virtual machines on a given host.

If you don't have good criteria to filter on, it is recommended to not use the properties like 'predefined list of elements' that is computationally very expensive, and instead use the object tree chooser.