[Alerting] discrepancy in typing of index threshold "index" parameter - server vs ui

[pmuellr]

I just noticed that I got an error thrown in the UI when I tried to display an alert I created with kbn-alert.

The error occurred here:

kibana/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_alert_types/threshold/expression.tsx

Line 186 in f090775

selectedOptions={(index || []).map((anIndex: string) => {

At this point, the value of index was a string, but the code assumed it was an array. That's what's specified in it's type:

kibana/x-pack/plugins/triggers_actions_ui/public/application/components/builtin_alert_types/threshold/types.ts

Lines 27 to 28 in 1e45e98

	export interface IndexThresholdAlertParams {
	index: string[];

However, the alert type itself has index spec'd as string || string[]:

kibana/x-pack/plugins/alerting_builtins/server/alert_types/index_threshold/lib/core_query_types.ts

Lines 14 to 19 in 1e45e98

	export const CoreQueryParamsSchemaProperties = {
	// name of the indices to search
	index: schema.oneOf([
	schema.string({ minLength: 1 }),
	schema.arrayOf(schema.string({ minLength: 1 }), { minSize: 1 }),
	]),

So, that all makes sense, the alert was created at the API level, not the UI, and passed it's validation, but that shape is not valid within the UI.

I'm a little surprised at seeing this, it seems to indicate that I haven't edited in the UI and alerts I've created at the command-line, but ... I'd swear I have. Ah well ...

We'll need to fix this up so they are compatible.

[elasticmachine]

Pinging @elastic/kibana-alerting-services (Team:Alerting Services)

[pmuellr]

I'm tempted to change the alert type to make the index a string array, matching the ui, however it is possible someone has already created alerts with a string value instead of a string array.

So it seems like we'll need to change the UI to be more flexible and support string | string[]