150 lines
3.6 KiB
Markdown
150 lines
3.6 KiB
Markdown
# Validation
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Redis OM uses [Pydantic][pydantic-url] behind the scenes to validate data at runtime, based on the model's type annotations.
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## Basic Type Validation
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Validation works for basic type annotations like `str`. Thus, given the following model:
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```python
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import datetime
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from typing import Optional
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from pydantic import EmailStr
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from redis_om import HashModel
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class Customer(HashModel):
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first_name: str
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last_name: str
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email: EmailStr
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join_date: datetime.date
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age: int
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bio: Optional[str]
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```
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... Redis OM will ensure that `first_name` is always a string.
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But every Redis OM model is also a Pydantic model, so you can use existing Pydantic validators like `EmailStr`, `Pattern`, and many more for complex validation!
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## Complex Validation
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Let's see what happens if we try to create a `Customer` object with an invalid email address.
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```python
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import datetime
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from typing import Optional
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from pydantic import EmailStr, ValidationError
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from redis_om import HashModel
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class Customer(HashModel):
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first_name: str
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last_name: str
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email: EmailStr
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join_date: datetime.date
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age: int
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bio: Optional[str]
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# We'll get a validation error if we try to use an invalid email address!
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try:
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Customer(
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first_name="Andrew",
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last_name="Brookins",
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email="Not an email address!",
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join_date=datetime.date.today(),
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age=38,
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bio="Python developer, works at Redis, Inc."
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)
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except ValidationError as e:
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print(e)
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"""
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pydantic.error_wrappers.ValidationError: 1 validation error for Customer
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email
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value is not a valid email address (type=value_error.email)
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"""
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```
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As you can see, creating the `Customer` object generated the following error:
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```
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Traceback:
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pydantic.error_wrappers.ValidationError: 1 validation error for Customer
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email
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value is not a valid email address (type=value_error.email)
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```
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We'll also get a validation error if we change a field on a model instance to an invalid value and then try to save the model:
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```python
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import datetime
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from typing import Optional
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from pydantic import EmailStr, ValidationError
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from redis_om import HashModel
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class Customer(HashModel):
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first_name: str
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last_name: str
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email: EmailStr
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join_date: datetime.date
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age: int
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bio: Optional[str]
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andrew = Customer(
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first_name="Andrew",
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last_name="Brookins",
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email="andrew.brookins@example.com",
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join_date=datetime.date.today(),
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age=38,
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bio="Python developer, works at Redis, Inc."
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)
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andrew.email = "Not valid"
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try:
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andrew.save()
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except ValidationError as e:
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print(e)
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"""
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pydantic.error_wrappers.ValidationError: 1 validation error for Customer
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email
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value is not a valid email address (type=value_error.email)
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"""
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```
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Once again, we get the validation error:
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```
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Traceback:
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pydantic.error_wrappers.ValidationError: 1 validation error for Customer
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email
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value is not a valid email address (type=value_error.email)
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```
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## Constrained Values
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If you want to use any of the constraints.
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Pydantic includes many type annotations to introduce constraints to your model field values.
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The concept of "constraints" includes quite a few possibilities:
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* Strings that are always lowercase
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* Strings that must match a regular expression
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* Integers within a range
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* Integers that are a specific multiple
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* And many more...
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All of these constraint types work with Redis OM models. Read the [Pydantic documentation on constrained types](https://pydantic-docs.helpmanual.io/usage/types/#constrained-types) to learn more.
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[pydantic-url]: https://github.com/samuelcolvin/pydantic
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