reactjs - Slide Material-UI无法读取 "undefined"的属性样式

Question

我最近在我的项目中实现了 Material-UI Slide，想问是否有人可以向我解释为什么当我这样编写代码时代码可以工作:

{selectedItem && selectedItem.modal && selectedItem.modal.body ? (
    selectedItem.modal.body.map((section, key) => (
      <Section section={section} key={key} />
    ))
  ) : (
    <Slide
      direction={animate === 'stepIn' ? 'right' : 'left'}
      in={animate === 'idle'}
    >
      <Grid container={true} spacing={3}>
        {items.map((item, key) => (
          <Grid item={true} xs={6} md={4} lg={3} key={key}>
            <MaterialCard
              key={key}
              onClick={onCardClicked(item)}
              className={classes.card}
            >
              <CardActionArea className={classes.cardArea}>
                <CardMedia
                  image={item.image || undefined}
                  component="img"
                />

                <CardContent className={classes.cardContent}>
                  <Typography
                    component="p"
                    className={classes.cardContentTypographyHeader}
                  >
                    <Hyphenated language={de}>{item.label}</Hyphenated>
                  </Typography>

                  {item.description ? (
                    <Typography
                      component="p"
                      className={classes.cardContentTypography}
                    >
                      <Hyphenated language={de}>
                        {item.description}
                      </Hyphenated>
                    </Typography>
                  ) : null}
                </CardContent>
              </CardActionArea>

              {selectedItem && selectedItem.id === item.id ? (
                <>
                  <div className={classes.cardSelectedOverlay} />
                  <Done className={classes.cardSelectedOverlayIcon} />
                </>
              ) : null}
            </MaterialCard>
          </Grid>
        ))}
      </Grid>
    </Slide>

但是当我将section.map移动到幻灯片内时无法编译。我也想为即将到来的部分制作动画。

<Slide
    direction={animate === 'stepIn' ? 'right' : 'left'}
    in={animate === 'idle'}
  >
    {selectedItem && selectedItem.modal && selectedItem.modal.body ? (
      selectedItem.modal.body.map((section, key) => (
        <Section section={section} key={key} />
      ))
    ) : (
      <Grid container={true} spacing={3}>
        {items.map((item, key) => (
          <Grid item={true} xs={6} md={4} lg={3} key={key}>
            <MaterialCard
              key={key}
              onClick={onCardClicked(item)}
              className={classes.card}
            >
              <CardActionArea className={classes.cardArea}>
                <CardMedia
                  image={item.image || undefined}
                  component="img"
                />

                <CardContent className={classes.cardContent}>
                  <Typography
                    component="p"
                    className={classes.cardContentTypographyHeader}
                  >
                    <Hyphenated language={de}>{item.label}</Hyphenated>
                  </Typography>

                  {item.description ? (
                    <Typography
                      component="p"
                      className={classes.cardContentTypography}
                    >
                      <Hyphenated language={de}>
                        {item.description}
                      </Hyphenated>
                    </Typography>
                  ) : null}
                </CardContent>
              </CardActionArea>

              {selectedItem && selectedItem.id === item.id ? (
                <>
                  <div className={classes.cardSelectedOverlay} />
                  <Done className={classes.cardSelectedOverlayIcon} />
                </>
              ) : null}
            </MaterialCard>
          </Grid>
        ))}
      </Grid>
    )}
  </Slide>

该代码适用于每张卡片，但内部带有模态框的卡片除外。模态包含例如文本，文本输入。当我单击其中包含模式的卡片时，我收到此错误:

感谢您的帮助!

Answer 1

在 Slide's children prop 的文档中你可以找到:

A single child content element.

⚠️ Needs to be able to hold a ref.

Slide uses React.cloneElement 为单个 child 添加 ref 和 props。如果有多个 child 或者如果 children是一个数组(即使该数组只包含一个子数组)，则 Slide将收到您遇到的错误，因为 children.props未定义，它试图引用 children.props.style .

下面是一个小例子，可以帮助更好地理解错误的原因:

import React from "react";
import ReactDOM from "react-dom";

const MockSlide = ({ children }) => {
  if (children.props) {
    return (
      <div>
        {children}
        children.props is defined
      </div>
    );
  }
  return (
    <div>
      {children}
      children.props is not defined
    </div>
  );
};
const sectionArray = [
  "An array also causes problems (even if only one element)"
];
function App() {
  return (
    <div className="App">
      <MockSlide>
        <div>Single child works fine</div>
      </MockSlide>
      <br />
      <br />
      <MockSlide>
        <div>Multiple children</div>
        <div>causes problems with Slide</div>
      </MockSlide>
      <br />
      <br />
      <MockSlide>
        {sectionArray.map(section => {
          return <div>{section}</div>;
        })}
      </MockSlide>
    </div>
  );
}

const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);

一个可能的解决方案是将所有内容包装在 Slide 中在一个<div>元素。