High performance Form component with data scope management. Including data collection, verification, and styles.
## When to use
- When you need to create an instance or collect information.
- When you need to validate fields in certain rules.
## Form Component
You can align the controls of a `form` using the `layout` prop:
-`horizontal`:to horizontally align the `label`s and controls of the fields. (Default)
-`vertical`:to vertically align the `label`s and controls of the fields.
-`inline`:to render form fields in one line.
## Form Item Component
A form consists of one or more form fields whose type includes input, textarea, checkbox, radio, select, tag, and more. A form field is defined using `<a-form-item />`.
## API
### Form
| Property | Description | Type | Default Value | Version |
| --- | --- | --- | --- | --- |
| model | data of form component | object | | |
| rules | validation rules of form | object | | |
| hideRequiredMark | Hide required mark of all form items | Boolean | false | |
| labelAlign | text align of label of all items | 'left' \| 'right' | 'right' | |
| labelCol | The layout of label. You can set `span``offset` to something like `{span: 3, offset: 12}` or `sm: {span: 3, offset: 12}` same as with `<Col>` | [object](/components/grid/#Col) | | |
| wrapperCol | The layout for input controls, same as `labelCol` | [object](/components/grid/#Col) | | |
| colon | change default props colon value of Form.Item (only effective when prop layout is horizontal) | boolean | true | |
| validateOnRuleChange | whether to trigger validation when the `rules` prop is changed | boolean | true | |
| name | Form name. Will be the prefix of Field `id` | string | - | 2.0.0 |
| scrollToFirstError | Auto scroll to first failed field when submit | boolean \| [options](https://github.com/stipsan/scroll-into-view-if-needed/#options) | false | 2.0.0 |
| scrollToField | Scroll to field position | (name: [NamePath](#NamePath), options: [[ScrollOptions](https://github.com/stipsan/scroll-into-view-if-needed/tree/ece40bd9143f48caf4b99503425ecb16b0ad8249#options)]) => void | |
| resetFields | reset all the fields and remove validation result | — |
| clearValidate | clear validation message for certain fields. The parameter is name or an array of names of the form items whose validation messages will be removed. When omitted, all fields' validation messages will be cleared | Function(props: string \| array) |
### Form.Item
| Property | Description | Type | Default Value | Version |
| --- | --- | --- | --- | --- |
| name | a key of `model`. In the use of validate and resetFields method, the attribute is required | string | | 2.0.0 |
| rules | validation rules of form | object \| array | | |
| autoLink | Whether to automatically associate form fields. In most cases, you can use automatic association. If the conditions for automatic association are not met, you can manually associate them. See the notes below. | boolean | true | |
| colon | Used with `label`, whether to display `:` after label text. | boolean | true | |
| extra | The extra prompt message. It is similar to help. Usage example: to display error message and prompt message at the same time. | string\|slot | | |
| hasFeedback | Used with `validateStatus`, this option specifies the validation status icon. Recommended to be used only with `Input`. | boolean | false | |
| help | The prompt message. If not provided, the prompt message will be generated by the validation rule. | string\|slot | | |
| htmlFor | Set sub label `htmlFor`. | string | | |
| label | Label text | string\|slot | | |
| labelCol | The layout of label. You can set `span``offset` to something like `{span: 3, offset: 12}` or `sm: {span: 3, offset: 12}` same as with `<Col>` | [object](/components/grid/#Col) | | |
| labelAlign | text align of label | 'left' \| 'right' | 'right' | |
| required | Whether provided or not, it will be generated by the validation rule. | boolean | false | |
| validateStatus | The validation status. If not provided, it will be generated by validation rule. options: 'success' 'warning' 'error' 'validating' | string | | |
| wrapperCol | The layout for input controls, same as `labelCol` | [object](/components/grid/#Col) | | |
| validateFirst | Whether stop validate on first rule of error for this field. | boolean | false | |
| validateTrigger | When to validate the value of children node | string \| string[] | `change` | |
### Note
#### 3.x
Since version 3.0, Form.Item no longer hijacks child elements, but automatically checks through provider/inject dependency injection. This method can improve component performance, and there is no limit to the number of child elements. The same is true for child elements. It can be a high-level component that is further encapsulated.
You can reference [Customized Form Controls](#components-form-demo-customized-form-controls)
But it also has some disadvantages:
1. If the custom component wants Form.Item to be verified and displayed, you need to inject `const {id, onFieldChange, onFieldBlur} = useFormItemContext()` and call the corresponding method.
2. A Form.Item can only collect the data of one form item. If there are multiple form items, it will cause collection confusion, for example,
```html
<a-form-item>
<a-inputname="a"></a-input>
<a-inputname="b"></a-input>
</a-form-item>
```
As above Form.Item does not know whether to collect `name="a"` or `name=`b``, you can solve this kind of problem in the following two ways:
The second way is to wrap it with a custom component and call `useFormItemContext` in the custom component, It is equivalent to merging multiple form items into one.
Third, the component library provides an `a-form-item-rest` component, which will prevent data collection. You can put form items that do not need to be collected and verified into this component. It is the same as the first This method is very similar, but it does not generate additional dom nodes.
Form.Item hijacks the only child element and listens to the `blur` and `change` events to achieve the purpose of automatic verification, so please make sure that the form field is not wrapped by other elements. If there are multiple child elements, only the change of the first child element will be monitored.
If the form field to be monitored does not meet the conditions of automatic monitoring, you can associate the form field as follows:
| validator | custom validate function (Note: [callback must be called](https://github.com/ant-design/ant-design/issues/5155)) | function(rule, value, callback) | - |
| whitespace | treat required fields that only contain whitespace as errors | boolean | `false` |
See more advanced usage at [async-validator](https://github.com/yiminghe/async-validator).
### useForm (v2.2)
`useForm` is a method that can run independently of the Form component. It uses the Vue response mechanism to monitor and verify data, and returns the verification result. You can bind the verification result to any component, `Form. Item` only displays the results.
The following versions need to be provided separately by `@ant-design-vue/use` library, it is not recommended to continue to use, you should upgrade to version 2.2+ as soon as possible