Allow overriding data while saving

Now you can add save({ data: {}, mapData: data => data }) to allow
overriding data send to the backend.

This only works for save atm, saveAll is unchanged for now.

Author: abzainuddin

src/Model.js

@@ -620,15 +620,18 @@ export default class Model {
     }
 
     @action
-    save(options = {}) {
+    save({ data = {}, mapData = (x) => x, ...options } = {}) {
         this.clearValidationErrors();
         return this.wrapPendingRequestCount(
             this.__getApi()
             .saveModel({
                 url: options.url || this.url,
-                data: this.toBackend({
-                    fields: options.fields,
-                    onlyChanges: options.onlyChanges,
+                data: mapData({
+                    ...this.toBackend({
+                        fields: options.fields,
+                        onlyChanges: options.onlyChanges,
+                    }),
+                    ...data,
                 }),
                 isNew: this.isNew,
                 requestOptions: omit(options, 'url'),

src/__tests__/Model.js

@@ -1068,6 +1068,36 @@ describe('requests', () => {
         return animal.save({ params: { branch_id: 1 } });
     });
 
+    test('save with custom data', () => {
+        const animal = new Animal();
+        mock.onAny().replyOnce(config => {
+            expect(JSON.parse(config.data)).toEqual({ id: null, name: '', extra_data: 'can be saved' });
+            return [201, {}];
+        });
+
+        return animal.save({ data: { extra_data: 'can be saved' } });
+    });
+
+    test('save with mapped data', () => {
+        const animal = new Animal();
+        mock.onAny().replyOnce(config => {
+            expect(JSON.parse(config.data)).toEqual({ id: 'overwritten', name: '' });
+            return [201, {}];
+        });
+
+        return animal.save({ mapData: data => ({ ...data, id: 'overwritten' }) });
+    });
+
+    test('save with custom and mapped data', () => {
+        const animal = new Animal();
+        mock.onAny().replyOnce(config => {
+            expect(JSON.parse(config.data)).toEqual({ id: 'overwritten', name: '', extra_data: 'can be saved' });
+            return [201, {}];
+        });
+
+        return animal.save({ data: { extra_data: 'can be saved' }, mapData: data => ({ ...data, id: 'overwritten' }) });
+    });
+
     test('save all with relations', () => {
         const animal = new Animal(
             {