Hello Gollavilli,

If it a user input so you can do validation first before saving data. you can check below URL for form and input fields validation then you can apply your own logic for validation (for example Rate > 0) and set validation message for field

https://success.outsystems.com/Documentation/11/Developing_an_Application/Design_UI/Forms/Validate_the_fields_of_a_form

Hi Gollavilli, 

For your use-case, one of the work-around solutions would be to set the Number Column min value to 0

Implementation Steps:

• Define the Grid OnInitiazlie event handler
• In the OnInitiazlie event handler action flow execute the below mentioned JS to set the min value to 0 

JavaScript Snippet:

var grid = GridAPI.GridManager.GetGridById($parameters.GridWidgetId);

grid.getColumn($parameters.Binding)._configs.getProviderConfig().editor._min = 0;

Refer to the attached oml solution.

Demo Screen: DG_OnlyPositiveNumber

I hope this helps you!

Kind regards,

Benjith Sam