Show ML jobs on chart when only one environment

Make it so if you're looking at the latency chart for a service with only one environment, while the environment selector is set to "All", it uses the single environment so the ML will be shown.

It does this by overriding the uiFilters in this case.

Rename the exported function from use_transaction_latency_chart_fetcher to match the file name.

Fixes elastic#86775.

x-pack/plugins/apm/public/components/shared/charts/latency_chart/index.tsx

@@ -12,7 +12,7 @@ import { LatencyAggregationType } from '../../../../../common/latency_aggregatio
 import { getDurationFormatter } from '../../../../../common/utils/formatters';
 import { useLicenseContext } from '../../../../context/license/use_license_context';
 import { useUrlParams } from '../../../../context/url_params_context/use_url_params';
-import { useTransactionLatencyChartsFetcher } from '../../../../hooks/use_transaction_latency_chart_fetcher';
+import { useTransactionLatencyChartFetcher } from '../../../../hooks/use_transaction_latency_chart_fetcher';
 import { TimeseriesChart } from '../../../shared/charts/timeseries_chart';
 import {
   getMaxY,
@@ -40,7 +40,7 @@ export function LatencyChart({ height }: Props) {
   const {
     latencyChartsData,
     latencyChartsStatus,
-  } = useTransactionLatencyChartsFetcher();
+  } = useTransactionLatencyChartFetcher();
 
   const { latencyTimeseries, anomalyTimeseries, mlJobId } = latencyChartsData;
 

x-pack/plugins/apm/public/hooks/use_transaction_latency_chart_fetcher.ts

@@ -6,14 +6,15 @@
 
 import { useMemo } from 'react';
 import { useParams } from 'react-router-dom';
-import { useFetcher } from './use_fetcher';
-import { useUrlParams } from '../context/url_params_context/use_url_params';
 import { useApmServiceContext } from '../context/apm_service/use_apm_service_context';
+import { useUrlParams } from '../context/url_params_context/use_url_params';
 import { getLatencyChartSelector } from '../selectors/latency_chart_selectors';
-import { useTheme } from './use_theme';
+import { useEnvironmentsFetcher } from './use_environments_fetcher';
+import { useFetcher } from './use_fetcher';
 import { useLatencyAggregationType } from './use_latency_Aggregation_type';
+import { useTheme } from './use_theme';
 
-export function useTransactionLatencyChartsFetcher() {
+export function useTransactionLatencyChartFetcher() {
   const { serviceName } = useParams<{ serviceName?: string }>();
   const { transactionType } = useApmServiceContext();
   const latencyAggregationType = useLatencyAggregationType();
@@ -22,15 +23,30 @@ export function useTransactionLatencyChartsFetcher() {
     urlParams: { start, end, transactionName },
     uiFilters,
   } = useUrlParams();
+  const { environments } = useEnvironmentsFetcher({ start, end, serviceName });
 
   const { data, error, status } = useFetcher(
     (callApmApi) => {
+      // If we have "All" selected in the environment selector, there won't be
+      // any ML jobs for the "All" environment. If we have a single environment
+      // (fetched with the `useEnvironmentsFetcher`) we can safely assume the
+      // user would want to see ML data for that single environment.
+      //
+      // We modify the uiFilters here, which is not advised, but the uiFilters
+      // are what's used to specify the environment when using this endpoint.
+      const environmentCount = environments.length;
+      const modifiedUiFilters =
+        environmentCount === 1
+          ? { ...uiFilters, environment: environments[0] }
+          : uiFilters;
+
       if (
         serviceName &&
         start &&
         end &&
         transactionType &&
-        latencyAggregationType
+        latencyAggregationType &&
+        environmentCount > 0
       ) {
         return callApmApi({
           endpoint:
@@ -42,14 +58,15 @@ export function useTransactionLatencyChartsFetcher() {
               end,
               transactionType,
               transactionName,
-              uiFilters: JSON.stringify(uiFilters),
+              uiFilters: JSON.stringify(modifiedUiFilters),
               latencyAggregationType,
             },
           },
         });
       }
     },
     [
+      environments,
       serviceName,
       start,
       end,