How to deal with the slow Appian grid selection validation?

Question

Hi, 
 I have a grid based on a RecordType, and I have coded a multi-selection mecanism inside the selectionSaveInto portion code. 
 When I select a line, some tests are made, but Appian takes 2 seconds to accept the selection (even if I do nothing, just click on a row). 
 Then I can select or deselect another line.... etc... 
 All works fine as, I let Appian finishing the work (progression bar is displayed at the top of the screen). 
 The problem goes when I click quickly on many lines: this creates some bugs. 
 
 How may I rid of this issue? is there any way to toggle enable/disable selection after having selected a row (while Appian is working)? 
 or is there any way to deactivate the mouse cursor during the Appian progression bar (as we could do with any other language like Java)? 
 Regards

Mike Schmitt · Answer

One potential issue here is that in your grid selection saveInto, you're doing maybe 5 or 6 consecutive operations for every single click, when you could probably accomplish the same thing in 1 or 2 operations.

Mike Schmitt · Answer

See my dramatically simplified example for some other options. Instead of doing 6 consecutive saves in your SaveInto, we simply save the row ID of the selected vehicle, then use some evaluation chaining in the local variables to resolve things like selected vehicle CDT list as well as calculated selected value sums. I'm not exactly clear on how you want to restrict row selection precisely, so I've given you 2 different options within the "disableRowSelectionWhen" parameter - basically one which will limit any new selections once the max has been exceeded, and a secondary measure which will prevent any item from being selected if it would cause the total value to exceed your limit. 
 a!localVariables(
 local!vehicles: {
 {
 id: 1,
 make: "Ford",
 model: "Taurus",
 value: "$200"
 },
 {
 id: 2,
 make: "Volvo",
 model: "760 TI",
 value: "$1500"
 },
 {
 id: 3,
 make: "Chevy",
 model: "Impala",
 value: "$11,000"
 }
 },
 
 local!selection: {},
 
 local!selectedVehicles: if(
 rule!PIRS_RULE_General_isListEmpty(local!selection),
 {},
 index(
 local!vehicles,
 local!selection
 )
 ),
 
 local!valMaxAuto: 5000,
 local!totalValueSelected: if(
 not(rule!PIRS_RULE_General_isListEmpty(local!selectedVehicles)),
 sum(
 a!forEach(
 items: local!selectedVehicles,
 expression: tointeger(fv!item.value)
 )
 ),
 0
 ),
 local!maxValueReached: local!totalValueSelected > local!valMaxAuto,
 
 
 a!sectionLayout(
 contents: {
 a!columnsLayout(
 columns: {
 a!columnLayout(
 contents: {
 a!cardLayout(
 contents: {
 a!gridField(
 label: "Read-only Grid",
 labelPosition: "ABOVE",
 data: local!vehicles,
 columns: {
 a!gridColumn(
 label: "Make",
 value: fv!row.make
 ),
 a!gridColumn(
 label: "Model",
 value: fv!row.model
 ),
 a!gridColumn(
 label: "Value",
 value: fv!row.value
 ),
 },
 selectable: true,
 disableRowSelectionWhen: or(
 
 /* allow rows to be un-selected, but no new rows to be selected, when max value is passed */
 and(
 not(contains(tointeger(local!selection), fv!identifier)),
 local!maxValueReached
 ),
 
 /* un-comment the following row to selectively disable rows that would cause max value to be exceeded */
 /*local!totalValueSelected + fv!row.value > local!valMaxAuto*/
 ),
 selectionStyle: "ROW_HIGHLIGHT",
 selectionValue: local!selection,
 
 selectionSaveInto: {
 
 /* you can basically just use this - since my example is using a dictionary, the index of the row will be saved -- when using a queried datasubset, you may need to adjust accordingly since the saved value will use the identifier instead */
 local!selection

 },
 validations: {}
 )
 },
 height: "AUTO",
 style: "NONE",
 marginBelow: "STANDARD"
 ),

 }
 ),
 a!columnLayout(
 contents: {}
 )
 }
 ),
 
 a!paragraphField(
 label:"ri!selectedVehicle",
 value: local!selectedVehicles
 )
 },
 showWhen: true
 )
)

Mike Schmitt · Answer

I can reproduce this behavior in Chrome on Appian Cloud. I'm not sure it's a bug per se - variable evaluation is quick but not guaranteed to be instantaneous. You might want to just set up validation on the grid to handle cases where someone "super-clicks" the rows.