feat: allow to use an Action Selector with only a fn callback. path i…

…s now optional

src/MorphismTree.ts

@@ -129,6 +129,10 @@ export class MorphismSchemaTree<Target, Source> {
       parentKeyPath = parentKeyPath ? `${parentKeyPath}.${actionKey}` : actionKey;
     } else {
       if (actionKey) {
+        if (isEmptyObject(partialSchema as any))
+          throw new Error(
+            `A value of a schema property can't be an empty object. Value ${JSON.stringify(partialSchema)} found for property ${actionKey}`
+          );
         // check if actionKey exists to verify if not root node
         this.add({ propertyName: actionKey, action: null }, parentKeyPath);
         parentKeyPath = parentKeyPath ? `${parentKeyPath}.${actionKey}` : actionKey;
@@ -214,10 +218,14 @@ export class MorphismSchemaTree<Target, Source> {
       // Action<Object>: a path and a function: [ destination : { path: 'source', fn:(fieldValue, items) }]
       return ({ object, items, objectToCompute }) => {
         let result;
-        if (Array.isArray(action.path)) {
-          result = aggregator(action.path, object);
-        } else if (isString(action.path)) {
-          result = get(object, action.path);
+        if (action.path) {
+          if (Array.isArray(action.path)) {
+            result = aggregator(action.path, object);
+          } else if (isString(action.path)) {
+            result = get(object, action.path);
+          }
+        } else {
+          result = object;
         }
 
         if (action.fn) {

src/morphism.spec.ts

@@ -353,6 +353,28 @@ describe('Morphism', () => {
           expect(errors.length).toBe(1);
         }
       });
+
+      it('should allow to use an action selector with a `fn` callback only', () => {
+        interface Target {
+          t1: string;
+        }
+        const schema = createSchema<Target>({ t1: { fn: value => value.s1 } });
+        const result = morphism(schema, { s1: 'value' });
+        expect(result.t1).toEqual('value');
+      });
+
+      it('should allow to use an action selector with a `fn` callback only along with validation options', () => {
+        interface Target {
+          t1: string;
+        }
+        const schema = createSchema<Target>({ t1: { fn: value => value.s1, type: string } });
+        const result = morphism(schema, { s1: 1234 });
+        const errors = reporter.report(result);
+        expect(errors).not.toBeNull();
+        if (errors) {
+          expect(errors.length).toBe(1);
+        }
+      });
     });
     describe('Function Predicate', function() {
       it('should support es6 destructuring as function predicate', function() {

src/types.ts

@@ -159,7 +159,7 @@ export type ActionAggregator<T extends unknown = unknown> = T extends object ? (
  *
  */
 export interface ActionSelector<Source = object, R = any> {
-  path: ActionString<Source> | ActionAggregator<Source>;
+  path?: ActionString<Source> | ActionAggregator<Source>;
   // | ((source: Source) => unknown);
   fn?: (fieldValue: any, object: Source, items: Source, objectToCompute: R) => R;
   type?: BasicTypes;