feat: add() support index param

src/List.tsx

@@ -12,7 +12,7 @@ interface ListField {
 }
 
 interface ListOperations {
-  add: (defaultValue?: StoreValue) => void;
+  add: (defaultValue?: StoreValue, index?: number) => void;
   remove: (index: number | number[]) => void;
   move: (from: number, to: number) => void;
 }
@@ -59,13 +59,31 @@ const List: React.FunctionComponent<ListProps> = ({ name, children }) => {
            * Always get latest value in case user update fields by `form` api.
            */
           const operations: ListOperations = {
-            add: defaultValue => {
+            add: (defaultValue, index?: number) => {
               // Mapping keys
-              keyManager.keys = [...keyManager.keys, keyManager.id];
-              keyManager.id += 1;
-
               const newValue = getNewValue();
-              onChange([...newValue, defaultValue]);
+
+              if (index >= 0 && index <= newValue.length) {
+                keyManager.keys = [
+                  ...keyManager.keys.slice(0, index),
+                  keyManager.id,
+                  ...keyManager.keys.slice(index),
+                ];
+                onChange([...newValue.slice(0, index), defaultValue, ...newValue.slice(index)]);
+              } else {
+                if (
+                  process.env.NODE_ENV !== 'production' &&
+                  (index < 0 || index > newValue.length)
+                ) {
+                  warning(
+                    false,
+                    'The second parameter of the add function should be a valid positive number.',
+                  );
+                }
+                keyManager.keys = [...keyManager.keys, keyManager.id];
+                onChange([...newValue, defaultValue]);
+              }
+              keyManager.id += 1;
             },
             remove: (index: number | number[]) => {
               const newValue = getNewValue();

tests/list.test.js

@@ -321,6 +321,58 @@ describe('Form.List', () => {
     matchKey(0, '3');
   });
 
+  it('add when the second param is number', () => {
+    let operation;
+    const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
+    const [wrapper, getList] = generateForm((fields, opt) => {
+      operation = opt;
+      return (
+        <div>
+          {fields.map(field => (
+            <Field {...field}>
+              <Input />
+            </Field>
+          ))}
+        </div>
+      );
+    });
+
+    act(() => {
+      operation.add();
+    });
+    act(() => {
+      operation.add('1', 2);
+    });
+
+    act(() => {
+      operation.add('2', -1);
+    });
+
+    expect(errorSpy).toHaveBeenCalledWith(
+      'Warning: The second parameter of the add function should be a valid positive number.',
+    );
+    errorSpy.mockRestore();
+
+    wrapper.update();
+    expect(getList().find(Field).length).toEqual(3);
+    expect(form.getFieldsValue()).toEqual({
+      list: [undefined, '1', '2'],
+    });
+
+    act(() => {
+      operation.add('0', 0);
+    });
+    act(() => {
+      operation.add('4', 3);
+    });
+
+    wrapper.update();
+    expect(getList().find(Field).length).toEqual(5);
+    expect(form.getFieldsValue()).toEqual({
+      list: ['0', undefined, '1', '4', '2'],
+    });
+  });
+
   describe('validate', () => {
     it('basic', async () => {
       const [, getList] = generateForm(
@@ -417,6 +469,52 @@ describe('Form.List', () => {
       expect(form.getFieldError(['list', 0])).toEqual(["'list.1' must be at least 5 characters"]);
       expect(wrapper.find('input').props().value).toEqual('test');
     });
+
+    it('when add() second param is number', async () => {
+      const [wrapper, getList] = generateForm(
+        (fields, { add }) => (
+          <div>
+            {fields.map(field => (
+              <Field {...field} rules={[{ required: true }, { min: 5 }]}>
+                <Input />
+              </Field>
+            ))}
+
+            <button
+              className="button"
+              type="button"
+              onClick={() => {
+                add('test4', 1);
+              }}
+            />
+
+            <button
+              className="button1"
+              type="button"
+              onClick={() => {
+                add('test5', 0);
+              }}
+            />
+          </div>
+        ),
+        {
+          initialValues: { list: ['test1', 'test2', 'test3'] },
+        },
+      );
+
+      expect(wrapper.find(Input)).toHaveLength(3);
+      await changeValue(getField(getList(), 0), '');
+      expect(form.getFieldError(['list', 0])).toEqual(["'list.0' is required"]);
+
+      wrapper.find('.button').simulate('click');
+      wrapper.find('.button1').simulate('click');
+
+      expect(wrapper.find(Input)).toHaveLength(5);
+      expect(form.getFieldError(['list', 1])).toEqual(["'list.0' is required"]);
+
+      await changeValue(getField(getList(), 1), 'test');
+      expect(form.getFieldError(['list', 1])).toEqual(["'list.1' must be at least 5 characters"]);
+    });
   });
 
   it('warning if children is not function', () => {