Reactjs 如何从'；反应'；使用'；Redux'；

从本质上说，这个应用程序在保存到数据库的视图中显示了一个“学生”列表。现在，我希望能够删除一个学生，并使其保持不变。我相信答案就在组件本身

这是我到目前为止所做的，这是我的学生部分：

import React, { Component } from "react";
import store from "../store";
import { scrubStudent } from "../reducers";

export default class Students extends Component {
  constructor(props) {
    super(props);
    this.state = store.getState();
    this.deleteStudent = this.deleteStudent.bind(this);
  }

  deleteStudent(itemIndex) {
    console.log(this.state);
    var students = this.state.students;
    store.dispatch(scrubStudent(this.state));
    students.splice(itemIndex, 1);
    this.setState({
      students: students
    });
  }

  render() {
    var students = this.props.students;
    return (
      <div className="container">
        <div className="sixteen columns">
          <h1 className="remove-bottom">Students</h1>
          <h5>List of current students and their campus</h5>
          <hr />
        </div>
        <div className="sixteen columns">
          <div className="example">
            <div>
              <table className="u-full-width">
                <thead>
                  <tr>
                    <th>#</th>
                    <th>Name</th>
                    <th>Email</th>
                    <th>Campus</th>
                  </tr>
                </thead>
                <tbody>
                  {students.map(function(student, index) {
                    return (
                      <tr key={index}>
                        <td>
                          {student.id}
                        </td>
                        <td>
                          {student.name}
                        </td>
                        <td>
                          {student.email}
                        </td>
                        <td>
                          {student.campus}
                        </td>
                        <td>
                          <a
                            className="button button-icon"
                            onClick={this.deleteStudent(index)}
                          >
                            <i className="fa fa-remove" />
                          </a>
                        </td>
                      </tr>
                    );
                  })}
                </tbody>
              </table>
            </div>
          </div>
        </div>
      </div>
    );
  }
}

我要探究原因

import React, { Component } from "react";
import store from "../store";
import { deleteStudent } from "../reducers";

export default class Students extends Component {
  constructor(props) {
    super(props);
    this.state = store.getState();
    this.deleteStudent = this.deleteStudent.bind(this);
  }

  componentDidMount() {
    this.unsubscribe = store.subscribe(function() {
      this.setState(store.getState());
    });
  }

  componentWillUnmount() {
    this.unsubscribe();
  }

  deleteStudent(index) {
    console.log(this.state);
    var students = this.state.students;
    store.dispatch(deleteStudent(index));
    this.state = store.getState();
  }

  render() {
    var students = this.props.students;
    return (
      <div className="container">
        <div className="sixteen columns">
          <h1 className="remove-bottom">Students</h1>
          <h5>List of current students and their campus</h5>
          <hr />
        </div>
        <div className="sixteen columns">
          <div className="example">
            <div>
              <table className="u-full-width">
                <thead>
                  <tr>
                    <th>#</th>
                    <th>Name</th>
                    <th>Email</th>
                    <th>Campus</th>
                  </tr>
                </thead>
                <tbody>
                  {students.map(function(student, index) {
                    return (
                      <tr key={index}>
                        <td>
                          {student.id}
                        </td>
                        <td>
                          {student.name}
                        </td>
                        <td>
                          {student.email}
                        </td>
                        <td>
                          {student.campus}
                        </td>
                        <td>
                          <a
                            className="button button-icon"
                            onClick={() => this.deleteStudent(student.id)}
                            key={index}
                          >
                            <i className="fa fa-remove" />
                          </a>
                        </td>
                      </tr>
                    );
                  }, this)}
                </tbody>
              </table>
            </div>
          </div>
        </div>
      </div>
    );
  }
}

---

应使用箭头函数，以便在映射函数中保留相关上下文：

{students.map((student, index) => {

---

这样，当您在函数中使用

This

时，它就是您当前的组件

下面的答案直接回答了出现错误的原因，但通过阅读代码，您缺少了Redux的一个基本点…**关注点分离**请参阅我的答案，了解一些相关信息@MatthewBrent事实上，当我测试此操作过程时，我达到了最大调用堆栈，在那里一切都出了问题！谢谢你的链接。@AntonioPavicevac Ortiz你检查我的答案了吗？你还有什么问题吗？@Dekel嘿，是的，我有！非常感谢。根据马修指出的，我还有一些其他的问题。我已经更新了我的问题，以反映到目前为止的进展情况！如果不知道上面代码中的第90行是哪一行，就很难帮上忙，但我的猜测是，这也是一个范围问题。当您使用

function（）{…}

时，您就失去了当前函数的作用域，这就是为什么我在回答中说您应该使用arrow函数的原因。

import { combineReducers } from "redux";
import axios from "axios";

// INITIAL STATE

const initialState = {
  students: [],
  campuses: []
};

//ACTION CREATORS

const UPDATE_NAME = "UPDATE_NAME";
const ADD_STUDENT = "ADD_STUDENT";
const DELETE_STUDENT = "DELETE_STUDENT";
const GET_STUDENTS = "GET_STUDENTS";
const UPDATE_CAMPUS = "UPDATE_CAMPUS";
const GET_CAMPUS = "GET_CAMPUS";
const GET_CAMPUSES = "GET_CAMPUSES";

// ACTION CREATORS

export function updateName(name) {
  const action = {
    type: UPDATE_NAME,
    name
  };
  return action;
}

export function addStudent(student) {
  return {
    type: ADD_STUDENT,
    student
  };
}

export function scrubStudent(student) {
  return {
    type: DELETE_STUDENT,
    student
  };
}

export function getStudents(students) {
  const action = {
    type: GET_STUDENTS,
    students
  };
  return action;
}

export function updateCampus(campus) {
  const action = {
    type: UPDATE_CAMPUS,
    campus
  };
  return action;
}

export function getCampus(campus) {
  const action = {
    type: GET_CAMPUS,
    campus
  };
  return action;
}

export function getCampuses(campuses) {
  const action = {
    type: GET_CAMPUSES,
    campuses
  };
  return action;
}

//THUNK CREATORS

export function fetchStudents() {
  return function thunk(dispatch) {
    return axios
      .get("/api/students")
      .then(function(res) {
        return res.data;
      })
      .then(function(students) {
        return dispatch(getStudents(students));
      })
      .catch(function(err) {
        return console.error(err);
      });
  };
}

export function postStudent(student) {
  return function thunk(dispatch) {
    return axios
      .post("/api/students", student)
      .then(function(res) {
        return res.data;
      })
      .then(function(newStudent) {
        return dispatch(addStudent(newStudent));
      })
      .catch(function(err) {
        return console.error(err);
      });
  };
}

export function deleteStudent(student) {
  return function thunk(dispatch) {
    return axios
      .delete("/api/students/" + student.toString())
      .then(function(res) {
        return res.data;
      })
      .then(function(student) {
        return dispatch(scrubStudent(student));
      })
      .catch(function(err) {
        return console.error(err);
      });
  };
}

export function fetchCampuses() {
  return function thunk(dispatch) {
    return axios
      .get("/api/campuses")
      .then(function(res) {
        return res.data;
      })
      .then(function(campuses) {
        return dispatch(getCampuses(campuses));
      })
      .catch(function(err) {
        return console.error(err);
      });
  };
}

export function postCampus(student) {
  return function thunk(dispatch) {
    return axios
      .post("/api/campuses", campuse)
      .then(function(res) {
        return res.data;
      })
      .then(function(newCampus) {
        return dispatch(getCampus(newCampus));
      })
      .catch(function(err) {
        return console.error(err);
      });
  };
}

// REDUCER

const rootReducer = function(state = initialState, action) {
  var newState = Object.assign({}, state);

  switch (action.type) {
    case GET_STUDENTS:
      newState.students = state.students.concat(action.students);
      return newState;

    case ADD_STUDENT:
      newState.students = state.students.concat([action.student]);
      return newState;

    case DELETE_STUDENT:
      newState.students = state.students.concat([action.student]);
      return newState;

    case GET_CAMPUSES:
      newState.campuses = state.campuses.concat(action.campuses);
      return newState;

    case GET_CAMPUS:
      newState.campuses = state.campuses.concat([action.campus]);
      return newState;

    default:
      return state;
  }
};

export default rootReducer;

{students.map((student, index) => {