Properly set extraColumns on group-report table for anomaly vs stoppage.

dashboard/dashboard/elements/group-report-page.html

Index: dashboard/dashboard/elements/group-report-page.html
diff --git a/dashboard/dashboard/elements/group-report-page.html b/dashboard/dashboard/elements/group-report-page.html
index b40ff87f1ce2565b05a24d61578777821b1112b0..71d8997af3a7ba4e018e82e9eb911287f8fbf562 100644
--- a/dashboard/dashboard/elements/group-report-page.html
+++ b/dashboard/dashboard/elements/group-report-page.html
@@ -142,20 +142,7 @@ found in the LICENSE file.
       properties: {
         extraColumns: {
           type: Array,
-          value: () => ([
-            {
-              'key': 'percent_changed',
-              'label': 'Delta %'
-            },
-            {
-              'key': 'absolute_delta',
-              'label': 'Abs Delta'
-            },
-            {
-              'key': 'units',
-              'label': 'Units'
-            }
-          ])
+          value: () => []
         },
         loading: {
           type: Boolean,
@@ -416,6 +403,47 @@ found in the LICENSE file.
       },
 
       /**
+       * Sets the extra columns on the alerts table based on the type of alerts
+       * in the list for the table.
+       */
+      setExtraColumns: function(alertList) {
+        // Make a set of types in the table.
+        var types = new Set(alertList.map(item => item.type));
+
+        // Check if there is only one type.
+        if (types.size === 1) {
+          if (types.has('anomaly')) {
+            // Only anomalies in the table. Use anomaly extraColumns.
+            this.set('extraColumns', [
+              {
+                'key': 'percent_changed',
+                'label': 'Delta %'
+              },
+              {
+                'key': 'absolute_delta',
+                'label': 'Abs Delta'
+              },
+              {
+                'key': 'units',
+                'label': 'Units'
+              }
+            ]);
+          } else {
+            // Only stoppage alerts in the table. Use stoppage extraColumns.
+            this.set('extraColumns', [
+              {
+                'key': 'last_row_date',
+                'label': 'Date'
+              }
+            ]);
+          }
+        } else {
+          // Either multiple or no types. Can't set extraColumns.
+          this.set('extraColumns', []);
+        }
+      },
+
+      /**
        * The url params determine what data to request from
        * /group_report. sid is a hash of a group of keys.
        */
@@ -448,6 +476,7 @@ found in the LICENSE file.
             this.xsrfToken = response['xsrf_token'];
             this.warningBug = response['warning_bug'];
             this.warningMessage = response['warning_message'];
+            this.setExtraColumns(response['alert_list']);
             this.alertList = response['alert_list'];
             this.selectedKeys = response['selected_keys'];
             if (this.warningMessage) {