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feat: useWatch support dynamic names #758

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merged 2 commits into from
Jul 2, 2025
Merged

feat: useWatch support dynamic names #758

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27328cb
feat: useWatch support dynamic names
zombieJ Jul 1, 2025
1c2a469
fix: lint
zombieJ Jul 1, 2025
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57 changes: 18 additions & 39 deletions docs/examples/debug.tsx
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Original file line number Diff line number Diff line change
@@ -1,51 +1,30 @@
import Form, { Field } from 'rc-field-form';
import React from 'react';

function WatchCom({ name }: { name: number }) {
const data = Form.useWatch(name);
return data;
}
import Input from './components/Input';

export default function App() {
const [form] = Form.useForm();
const [open, setOpen] = React.useState<boolean>(true);
const [keyName, setKeyName] = React.useState(true);

const data = React.useMemo(() => {
return Array.from({ length: 1 * 500 }).map((_, i) => ({
key: i,
name: `Edward King ${i}`,
age: 32,
address: `London, Park Lane no. ${i}`,
}));
}, []);
// const val = Form.useWatch(keyName ? 'name' : 'age', form);
const val = Form.useWatch(values => values[keyName ? 'name' : 'age'], form);

return (
<Form form={form}>
<div className="App">
{/* When I made the switch, it was very laggy */}
<button
onClick={() => {
setOpen(!open);
}}
>
Switch
</button>
<WatchCom name={0} />
<WatchCom name={1} />
{open ? (
<div className="flex gap-[5px] flex-wrap">
{data?.map(item => {
return (
<Field key={item.name} name={item.name}>
<input />
</Field>
);
})}
</div>
) : (
<h2>some thing</h2>
)}
</div>
<button
onClick={() => {
setKeyName(!keyName);
}}
>
Switch {String(keyName)}
</button>
<Field name="name" initialValue="bamboo">
<Input />
</Field>
<Field name="age" initialValue="light">
<Input />
</Field>
{val}
</Form>
);
}
114 changes: 52 additions & 62 deletions src/useWatch.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -7,10 +7,12 @@ import type {
InternalNamePath,
NamePath,
Store,
WatchCallBack,
WatchOptions,
} from './interface';
import { isFormInstance } from './utils/typeUtil';
import { getNamePath, getValue } from './utils/valueUtil';
import { useEvent } from '@rc-component/util';

type ReturnPromise<T> = T extends Promise<infer ValueType> ? ValueType : never;
type GetGeneric<TForm extends FormInstance> = ReturnPromise<ReturnType<TForm['validateFields']>>;
Expand All @@ -23,19 +25,6 @@ export function stringify(value: any) {
}
}

const useWatchWarning =
process.env.NODE_ENV !== 'production'
? (namePath: InternalNamePath) => {
const fullyStr = namePath.join('__RC_FIELD_FORM_SPLIT__');
const nameStrRef = useRef(fullyStr);

warning(
nameStrRef.current === fullyStr,
'`useWatch` is not support dynamic `namePath`. Please provide static instead.',
);
}
: () => {};

function useWatch<
TDependencies1 extends keyof GetGeneric<TForm>,
TForm extends FormInstance,
Expand Down Expand Up @@ -123,56 +112,57 @@ function useWatch(
);
}

const namePath = getNamePath(dependencies);
const namePathRef = useRef(namePath);
namePathRef.current = namePath;

useWatchWarning(namePath);

useEffect(
() => {
// Skip if not exist form instance
if (!isValidForm) {
return;
}

const { getFieldsValue, getInternalHooks } = formInstance;
const { registerWatch } = getInternalHooks(HOOK_MARK);

const getWatchValue = (values: any, allValues: any) => {
const watchValue = options.preserve ? allValues : values;
return typeof dependencies === 'function'
? dependencies(watchValue)
: getValue(watchValue, namePathRef.current);
};

const cancelRegister = registerWatch((values, allValues) => {
const newValue = getWatchValue(values, allValues);
const nextValueStr = stringify(newValue);

// Compare stringify in case it's nest object
if (valueStrRef.current !== nextValueStr) {
valueStrRef.current = nextValueStr;
setValue(newValue);
}
});

// TODO: We can improve this perf in future
const initialValue = getWatchValue(getFieldsValue(), getFieldsValue(true));

// React 18 has the bug that will queue update twice even the value is not changed
// ref: https://github.com/facebook/react/issues/27213
if (value !== initialValue) {
setValue(initialValue);
}

return cancelRegister;
},

// We do not need re-register since namePath content is the same
// ============================== Form ==============================
const { getFieldsValue, getInternalHooks } = formInstance;
const { registerWatch } = getInternalHooks(HOOK_MARK);

// ============================= Update =============================
const triggerUpdate = useEvent((values?: any, allValues?: any) => {
const watchValue = options.preserve
? (allValues ?? getFieldsValue(true))
: (values ?? getFieldsValue());

const nextValue =
typeof dependencies === 'function'
? dependencies(watchValue)
: getValue(watchValue, getNamePath(dependencies));

if (stringify(value) !== stringify(nextValue)) {
setValue(nextValue);
}
});

// ============================= Effect =============================
const flattenDeps =
typeof dependencies === 'function' ? dependencies : JSON.stringify(dependencies);

// Deps changed
useEffect(() => {
// Skip if not exist form instance
if (!isValidForm) {
return;
}

triggerUpdate();

// eslint-disable-next-line react-hooks/exhaustive-deps
}, [isValidForm, flattenDeps]);
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方法的话，那每次 render 就是新的方法吧？

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我想的是，如果 dependencies 是方法，那判断返回的值，stringify处理，如果改变了就 render

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我想的是，如果 dependencies 是方法，那判断返回的值，stringify处理，如果改变了就 render

就是这么做的。

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现在是只要 render 了，flattenDeps 就变了

image

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哦，只是 triggerUpdate 执行了，但是 setValue 还是判断变没变

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嗯


// Value changed
useEffect(() => {
// Skip if not exist form instance
if (!isValidForm) {
return;
}

const cancelRegister = registerWatch((values, allValues) => {
triggerUpdate(values, allValues);
});

return cancelRegister;

// eslint-disable-next-line react-hooks/exhaustive-deps
[isValidForm],
);
}, [isValidForm]);

return value;
}
Expand Down
38 changes: 25 additions & 13 deletions tests/useWatch.test.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -426,25 +426,37 @@ describe('useWatch', () => {
errorSpy.mockRestore();
});

it('dynamic change warning', () => {
const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
it('dynamic change', () => {
const Demo: React.FC = () => {
const [form] = Form.useForm();
const [watchPath, setWatchPath] = React.useState('light');
Form.useWatch(watchPath, form);

React.useEffect(() => {
setWatchPath('bamboo');
}, []);
const value = Form.useWatch(watchPath, form);

return <Form form={form} />;
return (
<Form form={form} initialValues={{ light: 1128, bamboo: 903 }}>
<Field name="light">
<Input />
</Field>
<Field name="bamboo">
<Input />
</Field>
<button
onClick={() => {
setWatchPath('bamboo');
}}
>
{value}
</button>
</Form>
);
};
render(<Demo />);

expect(errorSpy).toHaveBeenCalledWith(
'Warning: `useWatch` is not support dynamic `namePath`. Please provide static instead.',
);
errorSpy.mockRestore();
const { container } = render(<Demo />);
const btn = container.querySelector('button')!;
expect(btn.textContent).toEqual('1128');

fireEvent.click(btn);
expect(btn.textContent).toEqual('903');
});

it('useWatch with preserve option', async () => {
Expand Down
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