pydantic_user_model_validation_with_error_handling.py

1from datetime import datetime
2from typing import List, Optional
3from pydantic import BaseModel, ValidationError
4
5class User(BaseModel):
6    id: int
7    name: str = 'John Doe'
8    signup_ts: Optional[datetime] = None
9    friends: List[int] = []
10
11external_data = {
12    'id': '123',
13    'signup_ts': '2019-06-01 12:22',
14    'friends': [1, 2, '3'],
15}
16
17user = User(**external_data)
18
19print(user.id)
20#> 123
21print(user.model_dump())
22"""
23{
24    'id': 123,
25    'name': 'John Doe',
26    'signup_ts': datetime.datetime(2019, 6, 1, 12, 22),
27    'friends': [1, 2, 3],
28}
29"""
30
31try:
32    User(signup_ts='broken', friends=[1, 2, 'not number'])
33except ValidationError as e:
34    print(e.json())
35"""
36[
37  {
38    "type": "missing",
39    "loc": ["id"],
40    "msg": "Field required",
41    "input": {"signup_ts": "broken", "friends": [1, 2, "not number"]},
42    "url": "https://errors.pydantic.dev/2/v/missing"
43  },
44  {
45    "type": "datetime_from_date_parsing",
46    "loc": ["signup_ts"],
47    "msg": "Input should be a valid datetime or date, first part must be a year",
48    "input": "broken",
49    "ctx": {"error": "unexpected character at line 1 column 1"},
50    "url": "https://errors.pydantic.dev/2/v/datetime_from_date_parsing"
51  },
52  {
53    "type": "int_parsing",
54    "loc": ["friends", 2],
55    "msg": "Input should be a valid integer, unable to parse string as an integer",
56    "input": "not number",
57    "url": "https://errors.pydantic.dev/2/v/int_parsing"
58  }
59]
60"""