為什麼我的程式碼沒有將資料加入我的 json 檔案？

Question

我正在製作一個註冊頁面，但似乎不明白為什麼它不起作用。

編輯：更新了程式碼以刪除 userObject。仍然無法取得將資料實際發佈到我的 json 檔案的程式碼。

新程式碼：

import { useState } from "react";

const Signup = () => {
  const [formData, setFormData] = useState({
    email: "",
    password: "",
    confirmPassword: "",
  });

  const handleInputChange = (event) => {
    setFormData({
      ...formData,
      [event.target.name]: event.target.value,
    });
  };

  console.log(formData)

  const handleSubmit = (event) => {
    event.preventDefault();

    console.log(formData); 

    fetch("http://localhost:8000/users", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(formData),
    }).then(() => {
      window.location.href = "/profile"; 
    });
  };

  return (
    <div>
      <h2>Sign up</h2>
      <form onSubmit={handleSubmit}>
        <div>
          <label>Email:</label>
          <input
            type="email"
            name="email"
            value={formData.email}
            onChange={handleInputChange}
            required
          />
        </div>
        <div>
          <label>Password:</label>
          <input
            type="password"
            name="password"
            value={formData.password}
            onChange={handleInputChange}
            required
          />
        </div>
        <div>
          <label>Confirm Password:</label>
          <input
            type="password"
            name="confirmPassword"
            value={formData.confirmPassword}
            onChange={handleInputChange}
            required
          />
        </div>
        <button type="submit">Sign up</button>
      </form>
    </div>
  );
};

export default Signup;

舊程式碼：

import { useState } from "react";

const Signup = () => {
  const [formData, setFormData] = useState({
    email: "",
    password: "",
    confirmPassword: "",
  });

  const handleInputChange = (event) => {
    setFormData({
      ...formData,
      [event.target.name]: event.target.value,
    });
  };

  console.log(formData)

  const handleSubmit = (event) => {
    event.preventDefault();
    const userObject = {
      email: formData.email,
      password: formData.password,
    };
 
    fetch("http://localhost:8000/users", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(userObject),
    }).then(() => {
      window.location.href = "/profile"; 
    });
  };

  console.log(userObject)

  return (
    <div>
      <h2>Sign up</h2>
      <form onSubmit={handleSubmit}>
        <div>
          <label>Email:</label>
          <input
            type="email"
            name="email"
            value={formData.email}
            onChange={handleInputChange}
            required
          />
        </div>
        <div>
          <label>Password:</label>
          <input
            type="password"
            name="password"
            value={formData.password}
            onChange={handleInputChange}
            required
          />
        </div>
        <div>
          <label>Confirm Password:</label>
          <input
            type="password"
            name="confirmPassword"
            value={formData.confirmPassword}
            onChange={handleInputChange}
            required
          />
        </div>
        <button type="submit">Sign up</button>
      </form>
    </div>
  );
};

export default Signup;

當我console.log formData時，它正在接收數據，但是當我嘗試console.log userObject時，它返回為未定義。我已經在谷歌上搜索了幾個小時，檢查了這裡類似問題的解決方案，並嘗試了不同的方法，但似乎無法將其保存到我的 json 文件中。希望以新的眼光我能得到一些幫助。謝謝！

Answer 1

這是正常的。很遺憾地告訴您，您的 console.log 函數沒有在正確的時間呼叫！

您的程式碼應該是：

import { useState } from "react";

const Signup = () => {
  const [formData, setFormData] = useState({
    email: "",
    password: "",
    confirmPassword: "",
  });

  const handleInputChange = (event) => {
    setFormData({
      ...formData,
      [event.target.name]: event.target.value,
    });
  };

  console.log(formData)

  const handleSubmit = (event) => {
    event.preventDefault();
    const userObject = {
      email: formData.email,
      password: formData.password,
    };

    console.log(userObject);
 
    fetch("http://localhost:8000/users", {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(userObject),
    }).then(() => {
      window.location.href = "/profile";
    });
  };

  return (
    

      
Sign up
      

        

          Email:
          
        
        

          Password:
          
        
        

          Confirm Password:
          
        
        Sign up
      
    
  );
};

export default Signup;

就像支出者所說：