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问题描述

我正在构建一个在某些情况下需要显示确认对话框的应用.

假设我想删除某些内容，然后我将发送一个类似 deleteSomething(id) 的操作，这样一些 reducer 将捕获该事件并填充对话框 reducer 以显示它.

当这个对话框提交时，我的怀疑就来了.

该组件如何根据分派的第一个动作分派正确的动作?
动作创建者应该处理这个逻辑吗?
我们可以在 reducer 中添加操作吗?

为了更清楚:

deleteThingA(id) =>显示带有问题的对话框 =>远程删除事物(id)createThingB(id) =>显示带有问题的对话框 =>远程创建事物(id)

所以我试图重用对话框组件.显示/隐藏对话框不是问题，因为这可以在减速器中轻松完成.我试图指定的是如何根据在左侧启动流程的动作从右侧分派动作.

解决方案

更新:React 16.0 通过 ReactDOM.createPortal

这里是真正的生产代码.再简单不过了:)

<联系按钮/></MenuHotspots.contacts>

编辑:刚刚发现允许渲染的 react-gateway进入您选择的节点(不一定是主体)

编辑:看来 react-popper 是一个不错的选择替代反应系绳.PopperJS 是一个只计算元素合适位置的库，不直接接触 DOM，让用户选择何时何地放置 DOM 节点，而 Tether 则直接附加到主体.

编辑:还有react-slot-fill这很有趣，并且可以通过允许将元素渲染到保留的元素槽中来帮助解决类似的问题，您可以将其放置在树中的任何位置

I'm building an app that needs to show a confirm dialog in some situations.

Let's say I want to remove something, then I'll dispatch an action like deleteSomething(id) so some reducer will catch that event and will fill the dialog reducer in order to show it.

My doubt comes when this dialog submits.

How can this component dispatch the proper action according to the first action dispatched?
Should the action creator handle this logic?
Can we add actions inside the reducer?

edit:

to make it clearer:

deleteThingA(id) => show dialog with Questions => deleteThingARemotely(id)

createThingB(id) => Show dialog with Questions => createThingBRemotely(id)

So I'm trying to reuse the dialog component. Showing/hiding the dialog it's not the problem as this can be easily done in the reducer. What I'm trying to specify is how to dispatch the action from the right side according to the action that starts the flow in the left side.

解决方案

Update: React 16.0 introduced portals through ReactDOM.createPortal link

Update: next versions of React (Fiber: probably 16 or 17) will include a method to create portals: ReactDOM.unstable_createPortal() link

Use portals

Dan Abramov answer first part is fine, but involves a lot of boilerplate. As he said, you can also use portals. I'll expand a bit on that idea.

The advantage of a portal is that the popup and the button remain very close into the React tree, with very simple parent/child communication using props: you can easily handle async actions with portals, or let the parent customize the portal.

What is a portal?

A portal permits you to render directly inside document.body an element that is deeply nested in your React tree.

The idea is that for example you render into body the following React tree:

<div className="layout">
  <div className="outside-portal">
    <Portal>
      <div className="inside-portal">
        PortalContent
      </div>
    </Portal>
  </div>
</div>

And you get as output:

<body>
  <div class="layout">
    <div class="outside-portal">
    </div>
  </div>
  <div class="inside-portal">
    PortalContent
  </div>
</body>

The inside-portal node has been translated inside <body>, instead of its normal, deeply-nested place.

When to use a portal

A portal is particularly helpful for displaying elements that should go on top of your existing React components: popups, dropdowns, suggestions, hotspots

Why use a portal

No z-index problems anymore: a portal permits you to render to <body>. If you want to display a popup or dropdown, this is a really nice idea if you don't want to have to fight against z-index problems. The portal elements get added do document.body in mount order, which means that unless you play with z-index, the default behavior will be to stack portals on top of each others, in mounting order. In practice, it means that you can safely open a popup from inside another popup, and be sure that the 2nd popup will be displayed on top of the first, without having to even think about z-index.

In practice

Most simple: use local React state: if you think, for a simple delete confirmation popup, it's not worth to have the Redux boilerplate, then you can use a portal and it greatly simplifies your code. For such a use case, where the interaction is very local and is actually quite an implementation detail, do you really care about hot-reloading, time-traveling, action logging and all the benefits Redux brings you? Personally, I don't and use local state in this case. The code becomes as simple as:

class DeleteButton extends React.Component {
  static propTypes = {
    onDelete: PropTypes.func.isRequired,
  };

  state = { confirmationPopup: false };

  open = () => {
    this.setState({ confirmationPopup: true });
  };

  close = () => {
    this.setState({ confirmationPopup: false });
  };

  render() {
    return (
      <div className="delete-button">
        <div onClick={() => this.open()}>Delete</div>
        {this.state.confirmationPopup && (
          <Portal>
            <DeleteConfirmationPopup
              onCancel={() => this.close()}
              onConfirm={() => {
                this.close();
                this.props.onDelete();
              }}
            />
          </Portal>
        )}
      </div>
    );
  }
}

Simple: you can still use Redux state: if you really want to, you can still use connect to choose whether or not the DeleteConfirmationPopup is shown or not. As the portal remains deeply nested in your React tree, it is very simple to customize the behavior of this portal because your parent can pass props to the portal. If you don't use portals, you usually have to render your popups at the top of your React tree for z-index reasons, and usually have to think about things like "how do I customize the generic DeleteConfirmationPopup I built according to the use case". And usually you'll find quite hacky solutions to this problem, like dispatching an action that contains nested confirm/cancel actions, a translation bundle key, or even worse, a render function (or something else unserializable). You don't have to do that with portals, and can just pass regular props, since DeleteConfirmationPopup is just a child of the DeleteButton

Conclusion

Portals are very useful to simplify your code. I couldn't do without them anymore.

Note that portal implementations can also help you with other useful features like:

Accessibility
Espace shortcuts to close the portal
Handle outside click (close portal or not)
Handle link click (close portal or not)
React Context made available in portal tree

react-portal or react-modal are nice for popups, modals, and overlays that should be full-screen, generally centered in the middle of the screen.

react-tether is unknown to most React developers, yet it's one of the most useful tools you can find out there. Tether permits you to create portals, but will position automatically the portal, relative to a given target. This is perfect for tooltips, dropdowns, hotspots, helpboxes... If you have ever had any problem with position absolute/relative and z-index, or your dropdown going outside of your viewport, Tether will solve all that for you.

You can, for example, easily implement onboarding hotspots, that expands to a tooltip once clicked:

Real production code here. Can't be any simpler :)

<MenuHotspots.contacts>
  <ContactButton/>
</MenuHotspots.contacts>

Edit: just discovered react-gateway which permits to render portals into the node of your choice (not necessarily body)

Edit: it seems react-popper can be a decent alternative to react-tether. PopperJS is a library that only computes an appropriate position for an element, without touching the DOM directly, letting the user choose where and when he wants to put the DOM node, while Tether appends directly to the body.

Edit: there's also react-slot-fill which is interesting and can help solve similar problems by allowing to render an element to a reserved element slot that you put anywhere you want in your tree

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