fix destructive recursion

Author: tsullivan

src/plugins/data/common/search/search_source/search_source.test.ts

@@ -141,6 +141,33 @@ describe('SearchSource', () => {
           ],
         }
       `);
+
+      // calling twice gives the same result: no searchSources in the hierarchy were modified
+      expect(searchSource.getFields(RECURSE)).toMatchInlineSnapshot(`
+        Object {
+          "aggs": 5,
+          "filter": Array [
+            Object {
+              "meta": Object {
+                "alias": null,
+                "disabled": false,
+                "index": "d180cae0-60c3-11eb-8569-bd1f5ed24bc9",
+                "negate": false,
+                "params": Object {},
+              },
+              "query": Object {
+                "range": Object {
+                  "@date": Object {
+                    "format": "strict_date_optional_time",
+                    "gte": "2016-01-27T18:11:05.010Z",
+                    "lte": "2021-01-27T18:11:05.010Z",
+                  },
+                },
+              },
+            },
+          ],
+        }
+      `);
     });
 
     test('recurses parents to get the entire filters: function filter', () => {
@@ -192,6 +219,33 @@ describe('SearchSource', () => {
           ],
         }
       `);
+
+      // calling twice gives the same result: no double-added filters
+      expect(searchSource.getFields(RECURSE)).toMatchInlineSnapshot(`
+        Object {
+          "aggs": 5,
+          "filter": Array [
+            Object {
+              "meta": Object {
+                "alias": null,
+                "disabled": false,
+                "index": "d180cae0-60c3-11eb-8569-bd1f5ed24bc9",
+                "negate": false,
+                "params": Object {},
+              },
+              "query": Object {
+                "range": Object {
+                  "@date": Object {
+                    "format": "strict_date_optional_time",
+                    "gte": "2016-01-27T18:11:05.010Z",
+                    "lte": "2021-01-27T18:11:05.010Z",
+                  },
+                },
+              },
+            },
+          ],
+        }
+      `);
     });
   });
 

src/plugins/data/common/search/search_source/search_source.ts

@@ -206,10 +206,13 @@ export class SearchSource {
           }
         }
 
-        // set filter to the array of non-function-type filters
-        this.setField('filter', thisFilter);
+        // add combined filters to the fields
+        const thisFields = {
+          ...this.fields,
+          filter: thisFilter,
+        };
 
-        return { ...parentFields, ...this.fields };
+        return { ...parentFields, ...thisFields };
       }
     }
     return { ...this.fields };