Editable Grid

The dynamic link to add a new row has a showWhen parameter. Add any condition to this to make it visible as needed.

You can use showwhen condition in the add row link. You can follow below code snippet.

a!localVariables(
  local!Items,
  local!files,
  {
    a!gridLayout(
      label: "Editable Grid",
      labelPosition: "ABOVE",
      headerCells: {
        a!gridLayoutHeaderCell(label: "Header Cell")
      },
      columnConfigs: {},
      rows: {
        a!gridRowLayout(
          contents: a!fileUploadField(
            label: "File Upload",
            value: local!files,
            saveInto: local!files
          )
        ),
        a!forEach(
          items: local!Items,
          expression: a!gridRowLayout(
            contents: a!fileUploadField(
              label: "File Upload",
              value: local!files,
              saveInto: local!files
            )
          )
        ),
        
      },
      addRowLink: a!dynamicLink(
        label: "Add row",
        value: local!Items,
        saveInto: 
        a!save(
          local!Items,
          append(local!Items,save!value)  
        ),
        showWhen: if(a!isNullOrEmpty(local!files),false(),true())
        
      ),
      selectionSaveInto: {},
      validations: {},
      shadeAlternateRows: true
    )
  }
  
)

Use showWhen parameter