Hiding a panel when nested list data source is empty

[Balazs]

Hello,

I have the following scenario and would like guidance on how to achieve the desired behavior.

I have a panel that contains:

• some common elements (for example, a title and metadata textboxes), and

• an outer list, which itself contains an inner list.

The data source has the following structure (simplified):

[
  [
    { "Text": "exampleText1", "Value": 1 },
    { "Text": "exampleText2", "Value": 2 },
    { "Text": "exampleText3", "Value": 3 }
  ],
  [
    { "Text": "exampleText21", "Value": 1 },
    { "Text": "exampleText22", "Value": 2 },
    { "Text": "exampleText23", "Value": 3 }
  ]
]

The outer list is bound to the main data source.
The inner list uses a data source binding like:

DataSource = Fields.Item

The panel that contains the lists also includes common elements (title, metadata) that should only be visible when there is data.

The issue I am facing is related to visibility:
I would like to hide the entire panel (including the common elements) when there are no elements at all in the data structure (for example, when the outer list is empty or when it does not contain any inner items).

I have already tried the following approach:

• creating a report parameter bound to the data source,

• attempting to evaluate a condition such as Count(Fields.Item) > 0,

• setting the parameter to true or false based on that condition,

• and then binding the panel’s Visible property to this parameter.

However, I was not able to make this approach work as expected.

Could you please advise on the recommended way to detect this condition and properly control the panel’s visibility in this scenario?

Thank you in advance for your help.

Best regards,
Balazs

[Petar]

Hi Balazs,

Thank you for the detailed explanation of your scenario.

Have you considered using an integer report parameter that is indeed bound to the data source, but uses `= Fields.Item.Length` for the value members and `= Max(Fields.Item.Length)` for the actual value?

Then, in the panel, you could add conditional formatting rules to control the visibility based on the following conditions:

The first check should address the scenario where the data source consists of an empty string:

[]

The second check should handle cases with empty nested arrays:

[
  [],
  []
]

If you believe I misunderstood your scenario, I would appreciate it if you could provide additional information so I can propose a better-suited suggestion.

Regards,
Petar
Progress Telerik