Flag nested fields as non-aggregatable (#51774)

* Flag nested fields as non-aggregatable

* Update tests

src/plugins/data/server/index_patterns/fetcher/lib/field_capabilities/field_caps_response.test.js

@@ -144,6 +144,13 @@ describe('index_patterns/field_capabilities/field_caps_response', () => {
         expect(child).toHaveProperty('subType', { nested: { path: 'nested_object_parent' } });
       });
 
+      it('returns nested sub-fields as non-aggregatable', () => {
+        const fields = readFieldCapsResponse(esResponse);
+        // Normally a keyword field would be aggregatable, but the fact that it is nested overrides that
+        const child = fields.find(f => f.name === 'nested_object_parent.child.keyword');
+        expect(child).toHaveProperty('aggregatable', false);
+      });
+
       it('handles fields that are both nested and multi', () => {
         const fields = readFieldCapsResponse(esResponse);
         const child = fields.find(f => f.name === 'nested_object_parent.child.keyword');

src/plugins/data/server/index_patterns/fetcher/lib/field_capabilities/field_caps_response.ts

@@ -182,6 +182,14 @@ export function readFieldCapsResponse(fieldCapsResponse: FieldCapsResponse): Fie
 
       if (Object.keys(subType).length > 0) {
         field.subType = subType;
+
+        // We don't support aggregating on nested fields, trying to do so in the UI will return
+        // blank results. For now we will stop showing nested fields as an option for aggregation.
+        // Once we add support for nested fields this condition should be removed and old index
+        // patterns should be migrated.
+        if (field.subType.nested) {
+          field.aggregatable = false;
+        }
       }
     }
   });

test/api_integration/apis/index_patterns/fields_for_wildcard_route/response.js

@@ -72,7 +72,7 @@ export default function ({ getService }) {
               readFromDocValues: true,
             },
             {
-              aggregatable: true,
+              aggregatable: false,
               esTypes: [
                 'keyword'
               ],
@@ -156,7 +156,7 @@ export default function ({ getService }) {
               readFromDocValues: true,
             },
             {
-              aggregatable: true,
+              aggregatable: false,
               esTypes: [
                 'keyword'
               ],