ant-design getFieldDecorator 无法获取自定义组件的值

1.自定义或第三方的表单控件，也可以与 Form 组件一起使用。只要该组件遵循以下的约定：

（1）提供受控属性 value 或其它与 valuePropName 的值同名的属性。

（2）提供 onChange 事件或 trigger 的值同名的事件。

（3）不能是函数式组件。

2.创建组件

components/PriceInput/index.js

import React, { PureComponent } from 'react';
import { Input, Select } from 'antd';

const Option = Select.Option;

export default class PriceInput extends PureComponent {
  constructor(props) {
    super(props);

    const value = props.value || {};
    this.state = {
      number: value.number || 0,
      currency: value.currency || 'rmb',
    };
  }

  componentWillReceiveProps(nextProps) {
    // Should be a controlled component.
    if ('value' in nextProps) {
      const value = nextProps.value;
      this.setState(value);
    }
  }

  handleNumberChange = (e) => {
    const number = parseInt(e.target.value || 0, 10);
    if (isNaN(number)) {
      return;
    }
    if (!('value' in this.props)) {
      this.setState({ number });
    }
    this.triggerChange({ number });
  }

  handleCurrencyChange = (currency) => {
    if (!('value' in this.props)) {
      this.setState({ currency });
    }
    this.triggerChange({ currency });
  }

  triggerChange = (changedValue) => {
    // Should provide an event to pass value to Form.
    const onChange = this.props.onChange;
    if (onChange) {
      onChange(Object.assign({}, this.state, changedValue));
    }
  }

  render() {
    const { size } = this.props;
    const state = this.state;
    return (
      <span>
        <Input
          type="text"
          size={size}
          value={state.number}
          onChange={this.handleNumberChange}
          style={{ width: '65%', marginRight: '3%' }}
        />
        <Select
          value={state.currency}
          size={size}
          style={{ width: '32%' }}
          onChange={this.handleCurrencyChange}
        >
          <Option value="rmb">RMB</Option>
          <Option value="dollar">Dollar</Option>
        </Select>
      </span>
    );
  }
}

3.调用

import React, { PureComponent } from 'react';
import { Form, Button } from 'antd';

const FormItem = Form.Item;

class Demo extends PureComponent {
  handleSubmit = (e) => {
    e.preventDefault();
    this.props.form.validateFields((err, values) => {
      if (!err) {
        console.log('Received values of form: ', values);
      }
    });
  }

  checkPrice = (rule, value, callback) => {
    if (value.number > 0) {
      callback();
      return;
    }
    callback('Price must greater than zero!');
  }

  render() {
    const { getFieldDecorator } = this.props.form;
    return (
      <Form layout="inline" onSubmit={this.handleSubmit}>
        <FormItem label="Price">
          {getFieldDecorator('price', {
            initialValue: { number: 0, currency: 'rmb' },
            rules: [{ validator: this.checkPrice }],
          })(<PriceInput />)}
        </FormItem>
        <FormItem>
          <Button type="primary" htmlType="submit">Submit</Button>
        </FormItem>
      </Form>
    );
  }
}

const WrappedDemo = Form.create()(Demo);

export default WrappedDemo;

.