Fixes issues with empty objects in toJson

Author: larf311

src/relationUtils.test.ts

@@ -1075,6 +1075,39 @@ describe('relationUtils', () => {
       },
     ]);
 
+    const nestedEmptyObject: ArrowRelation[] = plainToArrow([
+      {
+        relationId: '/:object/:name/String',
+        columns: [['obj1']],
+      },
+      {
+        relationId: '/:object/:arr/:[]/Int64/:id/Int64',
+        columns: [
+          [1, 2],
+          [1, 2],
+        ],
+      },
+      {
+        relationId: '/:object/:arr/:[]/Int64/:attrs',
+        columns: [[1]],
+      },
+      {
+        relationId: '/:object/:arr/:[]/Int64/:attrs/:attr1/String',
+        columns: [[2], ['value1']],
+      },
+      {
+        relationId: '/:idt/String',
+        columns: [['432412341234']],
+      },
+    ]);
+
+    const rootEmptyObject: ArrowRelation[] = plainToArrow([
+      {
+        relationId: '/:foo',
+        columns: [],
+      },
+    ]);
+
     it('should handle empty inputs', () => {
       const json = toJson([]);
 
@@ -1493,6 +1526,37 @@ describe('relationUtils', () => {
       });
     });
 
+    it('should handle nested empty objects', () => {
+      const json = toJson(nestedEmptyObject);
+
+      expect(json).toEqual({
+        idt: '432412341234',
+        object: {
+          name: 'obj1',
+          arr: [
+            {
+              id: 1,
+              attrs: {},
+            },
+            {
+              id: 2,
+              attrs: {
+                attr1: 'value1',
+              },
+            },
+          ],
+        },
+      });
+    });
+
+    it('should handle root empty objects', () => {
+      const json = toJson(rootEmptyObject);
+
+      expect(json).toEqual({
+        foo: {},
+      });
+    });
+
     it('should handle root prop', () => {
       const json = toJson(rootPropOutput);
 

src/relationUtils.ts

@@ -255,43 +255,53 @@ export function toJson(output: Relation[] | ArrowRelation[]): any {
       }
     }
 
-    for (let i = 0; i < relation.columns[0].length; i++) {
-      let pathToSet = propPath.slice();
-      let value: any;
-
-      for (let j = 0; j < relation.columns.length; j++) {
-        const colValue = relation.columns[j][i];
-        const pathIndex = columnLookup[j];
-
-        if (pathIndex !== undefined) {
-          const isArray = pathToSet[pathIndex] === ARRAY_MARKER;
-
-          if (isArray) {
-            const arrayIndex =
-              typeof colValue === 'number'
-                ? colValue - 1 // rel indices start from 1, not 0
-                : i; // wow, non-number array index?
-            pathToSet[columnLookup[j]] = arrayIndex;
-          } else {
-            pathToSet[columnLookup[j]] = colValue as string | number;
+    // if the last key is a symbol, then we need to add it to the prop path
+    // so we can set the value to an empty object
+    if (keys[keys.length - 1][0] === SYMBOL_PREFIX) {
+      propPath.push(keys[keys.length - 1].slice(1));
+    }
+
+    if (relation.columns.length === 0) {
+      set(result, propPath, {});
+    } else {
+      for (let i = 0; i < relation.columns[0].length; i++) {
+        let pathToSet = propPath.slice();
+        let value: any;
+
+        for (let j = 0; j < relation.columns.length; j++) {
+          const colValue = relation.columns[j][i];
+          const pathIndex = columnLookup[j];
+
+          if (pathIndex !== undefined) {
+            const isArray = pathToSet[pathIndex] === ARRAY_MARKER;
+
+            if (isArray) {
+              const arrayIndex =
+                typeof colValue === 'number'
+                  ? colValue - 1 // rel indices start from 1, not 0
+                  : i; // wow, non-number array index?
+              pathToSet[columnLookup[j]] = arrayIndex;
+            } else {
+              pathToSet[columnLookup[j]] = colValue as string | number;
+            }
+          } else if (j === relation.columns.length - 1) {
+            value = colValue;
           }
-        } else if (j === relation.columns.length - 1) {
-          value = colValue;
         }
-      }
 
-      if (
-        pathToSet[pathToSet.length - 1] === ARRAY_MARKER &&
-        keys[keys.length - 1] === EMPTY_ARRAY_MARKER
-      ) {
-        pathToSet = pathToSet.slice(0, -1);
-        value = [];
-      } else if (value === undefined) {
-        // present value
-        value = {};
-      }
+        if (
+          pathToSet[pathToSet.length - 1] === ARRAY_MARKER &&
+          keys[keys.length - 1] === EMPTY_ARRAY_MARKER
+        ) {
+          pathToSet = pathToSet.slice(0, -1);
+          value = [];
+        } else if (value === undefined) {
+          // present value
+          value = {};
+        }
 
-      set(result, pathToSet, value);
+        set(result, pathToSet, value);
+      }
     }
   });