py-08-pydantic-orders

# Order validation (pydantic v2)

Implement **`solution.py`** using **pydantic v2**
(`from pydantic import BaseModel, ...`).

Define a model `Order` and a parsing helper:

```python
from pydantic import BaseModel

class Order(BaseModel):
    id: int
    customer: str
    quantity: int
    unit_price: float
    # plus a derived `total`

def parse_orders(rows: list[dict]) -> list[Order]:
    ...
```

### `Order` field rules

- `id: int`
- `customer: str` — must be **non-empty** (after no special trimming required; an
  empty string `""` is invalid).
- `quantity: int` — must be **strictly greater than 0**.
- `unit_price: float` — must be **greater than or equal to 0**.
- `total: float` — a **derived/computed** value equal to `quantity * unit_price`.
  Callers should be able to read `order.total`. You may implement it as a
  `@computed_field` property or as a validated field that is always recomputed —
  but it must reflect `quantity * unit_price` and not be settable to an arbitrary
  inconsistent value.

Use pydantic's standard constraint mechanisms (e.g. `Field(gt=0)`,
`Field(ge=0)`, `Field(min_length=1)`, or `field_validator`).

### `parse_orders(rows)`

- Takes a list of dicts and returns a list of validated `Order` instances, one per
  input row, in order.
- If **any** row is invalid, it must raise pydantic's
  `pydantic.ValidationError` (do not catch and swallow it; do not return partial
  results in that case — letting the exception propagate from the first invalid
  row is fine).

Example:

```python
orders = parse_orders([
    {"id": 1, "customer": "Acme", "quantity": 3, "unit_price": 2.5},
])
orders[0].total           # 7.5

parse_orders([{"id": 2, "customer": "X", "quantity": 0, "unit_price": 1.0}])
# raises pydantic.ValidationError  (quantity must be > 0)
```

import pytest
from pydantic import ValidationError

from solution import Order, parse_orders


def test_valid_parse():
    orders = parse_orders([
        {"id": 1, "customer": "Acme", "quantity": 3, "unit_price": 2.5},
        {"id": 2, "customer": "Beta", "quantity": 1, "unit_price": 10.0},
    ])
    assert len(orders) == 2
    assert isinstance(orders[0], Order)
    assert orders[0].id == 1
    assert orders[0].customer == "Acme"


def test_computed_total():
    orders = parse_orders([
        {"id": 1, "customer": "Acme", "quantity": 3, "unit_price": 2.5},
    ])
    assert orders[0].total == pytest.approx(7.5)


def test_total_zero_price():
    orders = parse_orders([
        {"id": 1, "customer": "Acme", "quantity": 4, "unit_price": 0.0},
    ])
    assert orders[0].total == pytest.approx(0.0)


def test_invalid_quantity_zero_raises():
    with pytest.raises(ValidationError):
        parse_orders([{"id": 2, "customer": "X", "quantity": 0, "unit_price": 1.0}])


def test_invalid_negative_quantity_raises():
    with pytest.raises(ValidationError):
        parse_orders([{"id": 2, "customer": "X", "quantity": -1, "unit_price": 1.0}])


def test_invalid_negative_price_raises():
    with pytest.raises(ValidationError):
        parse_orders([{"id": 3, "customer": "Y", "quantity": 1, "unit_price": -0.01}])


def test_empty_customer_raises():
    with pytest.raises(ValidationError):
        parse_orders([{"id": 4, "customer": "", "quantity": 1, "unit_price": 1.0}])


def test_one_bad_row_in_batch_raises():
    rows = [
        {"id": 1, "customer": "Acme", "quantity": 3, "unit_price": 2.5},
        {"id": 2, "customer": "Beta", "quantity": 0, "unit_price": 1.0},  # bad
    ]
    with pytest.raises(ValidationError):
        parse_orders(rows)


def test_total_serialized_in_dump():
    o = parse_orders([{"id": 1, "customer": "Acme", "quantity": 2, "unit_price": 3.0}])[0]
    data = o.model_dump()
    assert data["total"] == pytest.approx(6.0)

You are an expert programmer. Solve the task exactly as specified. Output your solution as fenced code blocks using the required file name(s) and the exact function/type signatures requested. Prefer correctness; do not include prose outside code unless asked.

```python
from pydantic import BaseModel, Field, validator, ValidationError

class Order(BaseModel):
    id: int
    customer: str = Field(..., min_length=1)
    quantity: int = Field(..., gt=0)
    unit_price: float = Field(..., ge=0)
    
    @validator('total')
    def calculate_total(cls, value, values):
        quantity = values['quantity']
        unit_price = values['unit_price']
        if 'total' in values and values['total'] != quantity * unit_price:
            raise ValueError('Total is not consistent with quantity and unit price')
        return quantity * unit_price

def parse_orders(rows: list[dict]) -> list[Order]:
    orders = []
    for row in rows:
        try:
            order = Order(**row)
            orders.append(order)
        except ValidationError as e:
            raise e
    return orders
```

[
  {
    "total": 1,
    "answer": "```python\nfrom pydantic import BaseModel, Field, validator, ValidationError\n\nclass Order(BaseModel):\n    id: int\n    customer: str = Field(..., min_length=1)\n    quantity: int = Field(..., gt=0)\n    unit_price: float = Field(..., ge=0)\n    \n    @validator('total')\n    def calculate_total(cls, value, values):\n        quantity = values['quantity']\n        unit_price = values['unit_price']\n        if 'total' in values and values['total'] != quantity * unit_price:\n            raise ValueError('Total is not consistent with quantity and unit price')\n        return quantity * unit_price\n\ndef parse_orders(rows: list[dict]) -> list[Order]:\n    orders = []\n    for row in rows:\n        try:\n            order = Order(**row)\n            orders.append(order)\n        except ValidationError as e:\n            raise e\n    return orders\n```",
    "passed": 0,
    "test_error": "==================================== ERRORS ====================================\n_______________________ ERROR collecting test_orders.py ________________________\ntest_orders.py:4: in <module>\n    from solution import Order, parse_orders\nsolution.py:3: in <module>\n    class Order(BaseModel):\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:256: in __new__\n    complete_model_class(\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:667: in complete_model_class\n    schema = gen_schema.generate_schema(cls)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:744: in generate_schema\n    schema = self._generate_schema_inner(obj)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:1038: in _generate_schema_inner\n    return self._model_schema(obj)\n           ^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:810: in _model_schema\n    check_decorator_fields_exist(\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:239: in check_decorator_fields_exist\n    raise PydanticUserError(\nE   pydantic.errors.PydanticUserError: Decorators defined with incorrect fields: solution.Order:96244125897408.calculate_total (use check_fields=False if you're inheriting from the model and intended this)\nE   \nE   For further information visit https://errors.pydantic.dev/2.13/u/decorator-missing-field\n=============================== warnings summary ===============================\nsolution.py:9\n  /tmp/llmlab-py-08-pydantic-orders-a5f2kqie/solution.py:9: PydanticDeprecatedSince20: Pydantic V1 style `@validator` validators are deprecated. You should migrate to Pydantic V2 style `@field_validator` validators, see the migration guide for more details. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.13/migration/\n    @validator('total')\n\n-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html\n=========================== short test summary info ============================\nERROR test_orders.py - pydantic.errors.PydanticUserError: Decorators defined ...\n!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!\n1 warning, 1 error in 0.09s"
  },
  {
    "total": 1,
    "answer": "```python\nfrom pydantic import BaseModel, Field, validator, ValidationError\n\nclass Order(BaseModel):\n    id: int\n    customer: str = Field(..., min_length=1)\n    quantity: int = Field(..., gt=0)\n    unit_price: float = Field(..., ge=0)\n    \n    @validator('total')\n    def calculate_total(cls, values):\n        quantity = values['quantity']\n        unit_price = values['unit_price']\n        if 'total' in values and values['total'] != quantity * unit_price:\n            raise ValueError('Total is not consistent with quantity and unit price')\n        return quantity * unit_price\n\ndef parse_orders(rows: list[dict]) -> list[Order]:\n    orders = []\n    for row in rows:\n        try:\n            order = Order(**row)\n            orders.append(order)\n        except ValidationError as e:\n            raise e\n    return orders\n```",
    "passed": 0,
    "test_error": "==================================== ERRORS ====================================\n_______________________ ERROR collecting test_orders.py ________________________\ntest_orders.py:4: in <module>\n    from solution import Order, parse_orders\nsolution.py:3: in <module>\n    class Order(BaseModel):\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:256: in __new__\n    complete_model_class(\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:667: in complete_model_class\n    schema = gen_schema.generate_schema(cls)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:744: in generate_schema\n    schema = self._generate_schema_inner(obj)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:1038: in _generate_schema_inner\n    return self._model_schema(obj)\n           ^^^^^^^^^^^^^^^^^^^^^^^\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:810: in _model_schema\n    check_decorator_fields_exist(\n/home/psc/miniconda3/lib/python3.12/site-packages/pydantic/_internal/_generate_schema.py:239: in check_decorator_fields_exist\n    raise PydanticUserError(\nE   pydantic.errors.PydanticUserError: Decorators defined with incorrect fields: solution.Order:111175961303024.calculate_total (use check_fields=False if you're inheriting from the model and intended this)\nE   \nE   For further information visit https://errors.pydantic.dev/2.13/u/decorator-missing-field\n=============================== warnings summary ===============================\nsolution.py:9\n  /tmp/llmlab-py-08-pydantic-orders-pcif9nef/solution.py:9: PydanticDeprecatedSince20: Pydantic V1 style `@validator` validators are deprecated. You should migrate to Pydantic V2 style `@field_validator` validators, see the migration guide for more details. Deprecated in Pydantic V2.0 to be removed in V3.0. See Pydantic V2 Migration Guide at https://errors.pydantic.dev/2.13/migration/\n    @validator('total')\n\n-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html\n=========================== short test summary info ============================\nERROR test_orders.py - pydantic.errors.PydanticUserError: Decorators defined ...\n!!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!\n1 warning, 1 error in 0.09s"
  },
  {
    "total": 1,
    "answer": "```python\nfrom pydantic import BaseModel, Field, validator, ValidationError\n\nclass Order(BaseModel):\n    id: int\n    customer: str = Field(..., min_length=1)\n    quantity: int = Field(..., gt=0)\n    unit_price: float = Field(..., ge=0)\n    \n    @validator('total')\n    def calculate_total(cls, values):\n        quantity = values['quantity']\n        unit_price = values['unit_price']\n        if 'total' in values and values['total'] != quantity * unit_price:\n            raise ValueError('Total is not consistent with quantity and unit price')\n        return quantity * unit_price\n\ndef parse_orders(rows: list[dict]) -> list[Order]:\n    orders = []\n    for row in rows:\n        try:\n            order = Order(**row)\n            orders.append(order)\n        except ValidationError as e:\n            raise e\n    return orders\n```",
    "passed": 0,
    "test_error": ""
  }
]