如何在 react/JS 中映射数组和 object 后设置 State？

Question

我在 state 中有一个patients array 。 如果patient.room匹配roomStates.room那么我想将patient.roomStatus设置为roomStates[key].name 。 我的 function 如下，但我不明白为什么它不起作用。

Patient array

const patients = [
{name: "Jay”, room: "room01", roomStatus: ""}, 
{name: "Leo”, room: "room02", roomStatus: ""}, 
{name: "Jim", room: "room05", roomStatus: ""}
]

const  roomState = { 
room01: {type: "info", room: "room01", name: "Stopped"},
room02: {type: "normal",room: "room02", name: "InRoom"},
room05: {type: "normal", room: "room05",name: "InRoom"},
}

   handleRoomStateChange(roomStates) {

        Object.keys(roomStates).map((key) => {
            this.state.patients.map(patient => {

                if (patient.room === roomStates[key].room) {


                    this.setState({ ...patient, roomStatus: roomStates[key].name});
                }

            })

        });
    }

Answer 1

不要在每次循环迭代时设置 state，将数据保存到数组中，然后在循环执行完成后设置它：

handleRoomStateChange = roomStates => {
  const patients = Object.keys(roomStates).map(key => {
    return this.state.patients.map(patient => {
      if (patient.room === roomStates[key].room) {
        return {
          ...patient,
          roomStatus: roomStates[key].name
        };
      }
      return patient;
    });
  });

  this.setState({patients});
};

编辑：实际上返回一个嵌套数组，为了获得正确的数据结构，可以避免额外的map ：

handleRoomStateChange = roomStates => {
  const patients = this.state.patients.map(patient => {
    const roomKey = Object.keys(roomStates).find(key => key === patient.room);
    return {
      ...patient,
      roomStatus: roomStates[roomKey].name
    }
  });
  this.setState({ patients });
}