我想对某些用户操作执行导航，例如按钮的 onSubmit。假设用户单击“添加联系人”按钮，我希望反应路由器在主页“/”中重定向。目前我正面临这个问题--> TypeError: Cannot read properties of undefined (reading 'push')。作为初学者，我非常感谢专家的帮助。

添加联系人.js

import React, { Component } from "react";
import { Consumer } from "../../context";
import TextInputGroup from "../layout/TextInputGroup";
import { v4 as uuidv4 } from "uuid";
import { useNavigate } from "react-router-dom";

class AddContacts extends Component {
  state = {
    name: "",
    email: "",
    phone: "",
    errors: {},
  };
  onSubmit = (dispatch, e) => {
    e.preventDefault();

    const { name, email, phone } = this.state;

    //Check for errors

    if (name === "") {
      this.setState({ errors: { name: "Name is required" } });
      return;
    }
    if (email === "") {
      this.setState({ errors: { email: "Email is required" } });
      return;
    }
    if (phone === "") {
      this.setState({ errors: { phone: "Phone is required" } });
      return;
    }

    const newContact = {
      id: uuidv4(),
      name,
      email,
      phone,
    };
    dispatch({ type: "ADD_CONTACT", payload: newContact });

    this.setState({
      name: "",
      email: "",
      phone: "",
      errors: {},
    });
    this.props.navigate.push("/");
  };

  onChange = (e) => this.setState({ [e.target.name]: e.target.value });
  render() {
    const { name, email, phone, errors } = this.state;

    return (
      <Consumer>
        {(value) => {
          const { dispatch } = value;

          return (
            <div className="card mb-3">
              <div className="card-header">Add Contacts</div>
              <div className="card-body">
                <form onSubmit={this.onSubmit.bind(this, dispatch)}>
                  <TextInputGroup
                    label="Name"
                    name="name"
                    placeholder="Enter Name..."
                    value={name}
                    onChange={this.onChange}
                    error={errors.name}
                  />
                  <TextInputGroup
                    label="Email"
                    name="email"
                    type="email"
                    placeholder="Enter Email..."
                    value={email}
                    onChange={this.onChange}
                    error={errors.email}
                  />
                  <TextInputGroup
                    label="Phone"
                    name="phone"
                    placeholder="Enter Phone..."
                    value={phone}
                    onChange={this.onChange}
                    error={errors.phone}
                  />
                  <input
                    type="submit"
                    value="Add Contact"
                    className="btn btn-light btn-block mt-3"
                  />
                </form>
              </div>
            </div>
          );
        }}
      </Consumer>
    );
  }
}

export default AddContacts;

这是App.js 文件

import React, { Component } from "react";
import { BrowserRouter, Routes, Route, Link } from "react-router-dom";

import Contacts from "./components/contacts/Contacts";
import Header from "./components/layout/Header";
import AddContacts from "./components/contacts/AddContacts";
import About from "./components/pages/About";

import { Provider } from "./context";

import "bootstrap/dist/css/bootstrap.min.css";
import "./App.css";

function App() {
  return (
    <Provider>
      <BrowserRouter>
        <div className="App">
          <Header branding="Contact manager" />
          <div className="container">
            <Routes>
              <Route path="/" element={<Contacts />} />{" "}
              <Route path="/contact/add/*" element={<AddContacts />} />{" "}
              <Route path="about/*" element={<About />} />{" "}
            </Routes>{" "}
          </div>{" "}
        </div>{" "}
      </BrowserRouter>{" "}
    </Provider>
  );
}

export default App;

Issue

TypeError: Cannot read properties of undefined (reading 'push')

这是由于您尝试从navigateprop 不存在，它是未定义的。

this.props.navigate.push("/");

The useNavigatehook 仅与功能组件兼容，因此您想要/需要使用navigate对于类组件，您必须转换AddContacts到功能组件，或滚动您自己的自定义withRouter高阶组件注入“路由道具”，如withRouterHOC 来自react-router-domv5.x 做到了。

Solution

我不会介绍如何将类组件转换为函数组件。这是一个自定义示例withRouter HOC:

const withRouter = WrappedComponent => props => {
  const navigate = useNavigate();
  // etc... other react-router-dom v6 hooks

  return (
    <WrappedComponent
      {...props}
      navigate={navigate}
      // etc...
    />
  );
};

并装饰AddContacts具有新 HOC 的组件。

export default withRouter(AddContacts);

现在将通过navigate prop (以及您设置的任何其他内容）到装饰组件和this.navigate现在将被定义。

另外，导航API从v5变为v6，不再是直接的history正在使用的对象。navigate是一个函数而不是一个对象。要使用该函数，请调用该函数并传递 1 或 2 个参数，第一个是目标路径，第二个是可选的“选项”对象，其中replace and/or state键/值。

interface NavigateFunction {
  (
    to: To,
    options?: { replace?: boolean; state?: State }
  ): void;
  (delta: number): void;
}

现在导航如下：

this.props.navigate("/");