How to make a drop-down field concating multiple rows from a record?

Question

I have a local variable local!allProcesses: rule!myGetAllProcesses().data which contains data from a database. The columns are processId, processName, processYear and processQuarter. I now want to have choiceLabels of a drop-down menu which combines processName, processYear and processQuarter. The corresponding choiceValues will be the processIds. Obviously, the following code works only as long as I have only a single row in the database:
     choiceLabels:  {
        concat(
          {
            local!AllProcesses.processName
          },
          " for ",
          {
            local!AllProcesses.processYear
          },
          " Q",
          {
            local!AllProcesses.processQuarter
          }
        )
      },
      choiceValues: {local!allProcesses.processId},
Otherwise, for more than one row in the database, the error code will read
Could not display interface. Please check definition and inputs. Interface Definition: Expression evaluation error at function a!dropdownField [line 9]: A dropdown component [label=&ldquo;Process&rdquo;] has an invalid value for &ldquo;choiceValues&rdquo;. The choiceLabels and choiceValues arrays must be the same length, but choiceLabels was length 1 and choiceValues was length 2.
My question is: How to implement the merging of rows in the most efficient fashion, ideally in the interface itself? I read quite some old threads here in the community, and apparently in the newest Appian version there is a simple solution for it without introducing an expression rule or even a new, derived column in the database. Any guidance would be much appreciated!

floriang0001 · Accepted Answer

Thanks for the hint. Your code misses a few comas, but otherwise, the solution is to define a local variable as the following (and use it as choiceValues inside the interface).

a!foreach(
  items: local!AllProcesses,
  expression: concat(
    fv!item.processName,
    " for ",
    fv!item.processYear,
    " Q",
    fv!item.processQuarter
  )
}

.

stefanhelzle0001 · Answer

a!foreach(  items: local!AllProcesses,  expression: concat(    fv!item.processName    " for ",    fv!item.processYear    " Q",    fv!item.processQuarter  )},

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