fix: ensure joined data is null if the row is empty

even if `first` is configured on the joined query

Author: Joel Mukuthu

lib/KnormRelations.js

@@ -256,6 +256,7 @@ class KnormRelations {
             }
 
             join.parent = this;
+            // depended on by @knorm/postgres
             join.config.joined = true;
             join.config.index = ++this.config.index;
             // TODO: support custom aliases
@@ -327,18 +328,16 @@ class KnormRelations {
             // values while parsing the row but at a cost of code complexity
             const isEmpty = Object.values(data).every(value => value === null);
 
-            if (first) {
+            if (isEmpty) {
+              // TODO: test this next `if`
+              if (!parsedRow[as]) {
+                parsedRow[as] = null;
+              }
+            } else if (first) {
               parsedRow[as] = data;
             } else {
-              if (isEmpty) {
-                // TODO: test this
-                if (!parsedRow[as]) {
-                  parsedRow[as] = null;
-                }
-              } else {
-                parsedRow[as] = parsedRow[as] || [];
-                parsedRow[as].push(data);
-              }
+              parsedRow[as] = parsedRow[as] || [];
+              parsedRow[as].push(data);
             }
           });
         }

test/KnormRelations.spec.js

@@ -644,6 +644,23 @@ describe('KnormRelations', () => {
               [new User({ id: 1, name: 'User 1', image: new Image({ id: 1 }) })]
             );
           });
+
+          // TODO: requires fixes in @knorm/postgres
+          it.skip('includes other joined models as `null` if no rows were matched', async () => {
+            const query = new Query(User).leftJoin(new Query(Image).first());
+            await expect(
+              query.fetch(),
+              'to be fulfilled with sorted rows satisfying',
+              [
+                new User({
+                  id: 1,
+                  name: 'User 1',
+                  image: new Image({ id: 1 })
+                }),
+                new User({ id: 2, name: 'User 2', image: null })
+              ]
+            );
+          });
         });
 
         it('creates a left join to the model on all fields wih references', async () => {