How can I solve Uvicorn 422 Unprocessable Entity error with Flutter: fastapi

Question

I am trying to connect the backend(python) and frontend(flutter). Currently, I am connecting Signin Function.

Python Codes

1. user type
2. fastapi (signin function) code

class User(BaseModel):
    user_name: str
    real_name: str
    password: str
    phone_number: str
    email: str
    car_number: int
    car_color: str
    car_type: str
    # car_license: str
    homeroom: str
    user_type: str
    warning: list[str]
    penalty: int 

@router.post("/create")
async def create_user(new_user: User):
    data = new_user.dict()
    hashed_pw = Hash.bcrypt(new_user.password)
    data["password"] = hashed_pw
    result = router.database.user.insert_one(data)
    return {"message": "User registration successful."}

Flutter Codes

1. save(fastapi using through http.post code), saveTwo(fastapi using through dio pub dev)
2. How I am using the functions by using onpressed

Future save(String inputusername, String inputName, String inputpassword,
      String inputphoneNumber, String inputemail, String inputhomeroom) async {
    final Map<String, dynamic> userData = {
      'userName': inputusername,
      'realName': inputName,
      'password': inputpassword,
      'phoneNumber': inputphoneNumber,
      'email': inputemail,
      'carNumber': 0, // An integer, not a string
      'carColor': '0',
      'carType': '0',
      'homeroom': inputhomeroom, // Assuming inputhomeroom is a string
      'userType': 'Passenger',
      'warning': ['0'], // An empty list of strings
      'penalty': 0, // An integer, not a string
    };
    await http.post(Uri.parse('http://10.0.2.2:8000/user/create'),
        headers: <String, String>{
          'Content-Type': 'application/json; charset=UTF-8',
        },
        body: jsonEncode(userData));
  }



Future saveTwo(String inputusername, String inputName, String inputpassword,
      String inputphoneNumber, String inputemail, String inputhomeroom) async {
    final Map<String, dynamic> userData = {
      'userName': inputusername,
      'realName': inputName,
      'password': inputpassword,
      'phoneNumber': inputphoneNumber,
      'email': inputemail,
      'carNumber': 0, // An integer, not a string
      'carColor': '0',
      'carType': '0',
      'homeroom': inputhomeroom, // Assuming inputhomeroom is a string
      'userType': 'Passenger',
      'warning': ['0'], // An empty list of strings
      'penalty': 0, // An integer, not a string
    };

     await dio.post('http://10.0.2.2:8000/user/create', data: {

       'userName': inputusername,
       'realName': inputName,
       'password': inputpassword,
       'phoneNumber': inputphoneNumber,
       'email': inputemail,
       'carNumber': 0,
       'carColor': '0',
       'carType': '0',
       'homeroom': inputhomeroom,
       'userType': 'Passenger',
       'warning': ['0'],
       'penalty': 0
     }
     );
  }

TextButton(
        child: Text("Signin", style: TextStyle(color: Colors.white)),
                    onPressed: () {
                      save(
                          idController.text,
                          nameController.text,
                          pwController.text,
                          phoneController.text,
                          emailController.text,
                          homeroomController.text);
}
),

TextButton(
        child: Text("Signin", style: TextStyle(color: Colors.white)),
                    onPressed: () {
                      saveTwo(
                          idController.text,
                          nameController.text,
                          pwController.text,
                          phoneController.text,
                          emailController.text,
                          homeroomController.text);
}
),

I have tried into two different ways(save, saveTwo), but it only shows 422 error. I could not figure out whether I put wrong variable type of not. Please help me.

PS. I run python code on the unvicorn docs, and it worked.

Answer 1

API expects fields in snake case (user_name) while camel case (userName) is sent.

final Map<String, dynamic> userData = {
      'user_name': inputusername,
...
};