ReactJS Firebase添加多个文档失败

Question

我已将firebase云存储中的读写规则设置为true，但是，当我尝试向数据库中添加多个文档时，firebase控制台中仅显示第一个文档。我正在React中设置一个变量作为对象，然后将该对象添加到数据库中。没有来自前端或后端的反馈。如何添加更多文档？

import React, { useState } from 'react';
import Table from './Table';
import firebase from '../firebase';
const Form = () => {

    const[activity,setActivity]=useState({
        date:"",
        back:false,
        chest:false,
        biceps:false,
        triceps:false,
        forearms:false,
        quads:false,
        hams:false,
        calves:false,
        abs:false,
        delts:false,
        traps:false,
        tread:false,
        skip:"",
        cigs:"",
        com:""
    });
    const postValues = () => {
        firebase
        .firestore()
        .collection("exercises")
        .add({
          activity
        });
  
      setActivity({});
    };

    //for checkbox values
    const updateField = e => {
        setActivity({
          ...activity,
          [e.target.name]: e.target.checked
        });
      };

      //For non checkbox values
      const updateField2 = e => {
        setActivity({
          ...activity,
          [e.target.name]: e.target.value
        });
      };
    return (
        <div>
            ADD YOUR WORKOUT
            <form onSubmit={postValues}>
                Date<input type="date" name="date" onChange={updateField2}/>
                Back:<input type="checkbox" checked={activity.back} name="back" onChange={updateField}/>
                Chest:<input type="checkbox" name="chest" onChange={updateField}/>
                Biceps:<input type="checkbox" name="biceps" onChange={updateField}/>
                Triceps:<input type="checkbox" name="triceps" onChange={updateField}/>
                Forearms:<input type="checkbox" name="forearms" onChange={updateField}/>
                Quads:<input type="checkbox" name="quads" onChange={updateField}/>
                Hamstrings:<input type="checkbox" name="hams" onChange={updateField}/>
                Calves:<input type="checkbox" name="calves" onChange={updateField}/>
                Abs:<input type="checkbox" name="abs" onChange={updateField}/>
                Deltoids:<input type="checkbox" name="delts" onChange={updateField}/>
                Traps:<input type="checkbox" name="traps" onChange={updateField}/>
                Treadmill:<select name="tread" onChange={updateField2}>
                <option>0</option>
                    <option>5</option>
                    <option>10</option>
                    <option>15</option>
                    <option>20</option>
                    <option>25</option>
                    </select>
                Skipping:<select name="skip" onChange={updateField2}>
                    <option>0</option>
                    <option>5</option>
                    <option>10</option>
                    <option>15</option>
                    <option>20</option>
                    <option>25</option>
                    </select>
                Cigs:<select name="cigs" onChange={updateField2}>
                    <option>0</option>
                    <option>5</option>
                    <option>10</option>
                    <option>15</option>
                    <option>20</option>
                    <option>20+</option>
                    </select>
                Comments:<textarea name="com" onChange={updateField2}></textarea>
                <button>Add record</button>
            </form>
        <Table />
        </div>
    );
};

export default Form;