Errors in expression rule when multiple matches from the database.

Please share your current version of the top 4 lines of code.  Here's what I think you would need to have currently for it to work (and not give the error message even when the query results in an empty return set):

a!localVariables(
  local!asset: rule!BC_QE_GetVAsset(
    partid: ri!asset.partId,
    isHazardous: 1
  ).data,
  
  a!formLayout(
    label: "Summary of Asset" & " " & property(local!asset, "partId", "[no matches found]"),

Hi Mike, 

Your coding worked. But facing another issue now. I am getting an error for the quantity field now. So I should be using property function for all the remaining fields? 

alVariables(
  local!asset:rule!BC_QE_GetVAsset(partid: ri!asset.partId,isHazardous: 1).data,
  a!formLayout(
    contents: {
      a!richTextDisplayField(
        value: {
          a!richTextItem(
            text: (
              "Summary of" & " " & "Asset" & " " & property(local!asset, "partId", null),
            ),
            color: "ACCENT",
            size: "MEDIUM_PLUS",
            style: "STRONG"
          )
        }
      ),
      a!boxLayout(
        label: "This asset is no longer available",
        showWhen: local!asset.quantity = 0,
        style: "#cc0000",
        marginBelow: "STANDARD"
      ),

Thanks

Yes, if there's any chance in the query returning an empty value, in such a way that "local!asset" would come back null rather than containing a valid dictionary, then you'd need to access its properties using property() to avoid the error.  But you should consider whether this is really a valid use case first - or whether you should be gatekeeping this at a higher level (in other words, only letting users access this interface when you already know the query will return a valid dictionary into local!asset).  If you can be sure of that, then you can access the properties directly using dot property notation.

Thank you Mike for your input.