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* Make compatible with pydantic v1 * Remove unused import * Remove unused ignores * Update pydantic version * Fix minor formatting issue * ⏪ Revert removing iterate_in_threadpool * ✨ Add backwards compatibility with Pydantic 0.32.2 with deprecation warnings * ✅ Update tests to not break when using Pydantic < 1.0.0 * 📝 Update docs for Pydantic version 1.0.0 * 📌 Update Pydantic range version to support from 0.32.2 * 🎨 Format test imports * ✨ Add support for Pydantic < 1.2 for populate_validators * ✨ Add backwards compatibility for Pydantic < 1.2.0 with required fields * 📌 Relax requirement for Pydantic to < 2.0.0 🎉 🚀 * 💚 Update pragma coverage for older Pydantic versions
63 lines
2.6 KiB
Markdown
63 lines
2.6 KiB
Markdown
The same way you can declare additional validation and metadata in path operation function parameters with `Query`, `Path` and `Body`, you can declare validation and metadata inside of Pydantic models using Pydantic's `Field`.
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## Import `Field`
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First, you have to import it:
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```Python hl_lines="2"
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{!./src/body_schema/tutorial001.py!}
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```
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!!! warning
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Notice that `Field` is imported directly from `pydantic`, not from `fastapi` as are all the rest (`Query`, `Path`, `Body`, etc).
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## Declare model attributes
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You can then use `Field` with model attributes:
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```Python hl_lines="9 10"
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{!./src/body_schema/tutorial001.py!}
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```
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`Field` works the same way as `Query`, `Path` and `Body`, it has all the same parameters, etc.
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!!! note "Technical Details"
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Actually, `Query`, `Path` and others you'll see next create objects of subclasses of a common `Param` class, which is itself a subclass of Pydantic's `FieldInfo` class.
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And Pydantic's `Field` returns an instance of `FieldInfo` as well.
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`Body` also returns objects of a subclass of `FieldInfo` directly. And there are others you will see later that are subclasses of the `Body` class.
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Remember that when you import `Query`, `Path`, and others from `fastapi`, <a href="https://fastapi.tiangolo.com/tutorial/path-params-numeric-validations/#recap" target="_blank">those are actually functions that return classes of the same name</a>.
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!!! tip
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Notice how each model's attribute with a type, default value and `Field` has the same structure as a path operation function's parameter, with `Field` instead of `Path`, `Query` and `Body`.
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## Schema extras
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In `Field`, `Path`, `Query`, `Body` and others you'll see later, you can declare extra parameters apart from those described before.
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Those parameters will be added as-is to the output JSON Schema.
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If you know JSON Schema and want to add extra information apart from what we have discussed here, you can pass that as extra keyword arguments.
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!!! warning
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Have in mind that extra parameters passed won't add any validation, only annotation, for documentation purposes.
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For example, you can use that functionality to pass a <a href="http://json-schema.org/latest/json-schema-validation.html#rfc.section.8.5" target="_blank">JSON Schema example</a> field to a body request JSON Schema:
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```Python hl_lines="20 21 22 23 24 25"
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{!./src/body_schema/tutorial002.py!}
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```
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And it would look in the `/docs` like this:
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<img src="/img/tutorial/body-schema/image01.png">
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## Recap
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You can use Pydantic's `Field` to declare extra validations and metadata for model attributes.
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You can also use the extra keyword arguments to pass additional JSON Schema metadata.
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