Add optional parameter modifierFiltersResults for disabling count of …

…$modify query results (#136)

* Add optional parameter modifierFiltersResults for disabling count of $modify query results

* Improve test case for modifierFiltersResults parameter

README.md

@@ -261,6 +261,9 @@ Note that all this eager related options are optional.
   See [`withSchema`](https://vincit.github.io/objection.js/api/query-builder/find-methods.html#withschema)
   documentation.
 
+- **`modifierFiltersResults`** - when `false` the `total` count of a `find()` query is calculated from the original result set, ignoring the `count` of any `$modify` query.
+  The default behaviour is to apply the count of the modifier to the result total, assuming that the modifier may influence the result total by filtering the result set. This can be used to workaround issues with `groupBy` and the result count. See [this issue](https://github.com/feathersjs-ecosystem/feathers-objection/issues/102) for a detailed explanation.
+
 ### Composite primary keys
 
 Composite primary keys can be passed as the `id` argument using the following

src/index.js

@@ -574,7 +574,7 @@ class Service extends AdapterService {
           countQuery.count({ total: countColumns });
         }
 
-        if (query && query.$modify) {
+        if (query && query.$modify && params.modifierFiltersResults !== false) {
           this.modifyQuery(countQuery, query.$modify);
         }
 

test/company.js

@@ -57,6 +57,9 @@ export default class Company extends Model {
     },
     withRelation: builder => {
       builder.withGraphFetched('employees');
+    },
+    withRelationAndGroupBy: builder => {
+      builder.withGraphFetched('employees').groupBy('id');
     }
   }
 

test/index.test.js

@@ -2098,6 +2098,49 @@ describe('Feathers Objection Service', () => {
       });
     });
 
+    it('params.modifierFiltersResults=false does not apply count from modify query', () => {
+      companies.options.paginate = {
+        default: 2,
+        max: 2
+      };
+
+      return companies.find({
+        query: { $modify: ['withRelationAndGroupBy'] }, modifierFiltersResults: false
+      }).then(data => {
+        expect(data.total).to.be.equal(2);
+        expect(data.data.length).to.be.equal(2);
+        expect(data.data[0].name).to.be.equal('Google');
+      });
+    });
+
+    it('params.modifierFiltersResults=true applies count from modify query', () => {
+      companies.options.paginate = {
+        default: 2,
+        max: 2
+      };
+
+      return companies.find({
+        query: { $modify: ['withRelationAndGroupBy'] }, modifierFiltersResults: true
+      }).then(data => {
+        expect(data.total).to.be.equal(1); // count result from GROUP BY
+        expect(data.data.length).to.be.equal(2);
+        expect(data.data[0].name).to.be.equal('Google');
+      });
+    });
+
+    it('params.modifierFiltersResults=undefined applies count from modify query', () => {
+      companies.options.paginate = {
+        default: 2,
+        max: 2
+      };
+
+      return companies.find({ query: { $modify: ['withRelationAndGroupBy'] } }).then(data => {
+        expect(data.total).to.be.equal(1); // count result from GROUP BY
+        expect(data.data.length).to.be.equal(2);
+        expect(data.data[0].name).to.be.equal('Google');
+      });
+    });
+
     it('allow $modify query with paginate, groupBy and joinRelation', () => {
       companies.options.paginate = {
         default: 1,