When working on some source code it is important to be aware of the runtimes in which it will run, so that you don't break these constraints.
There is some assistance in the IDE for this plus a lot of validation that is applied at build time and on CI, but it is useful to keep these constraints in mind as well.

See [Gradle runtimes](runtimes.md) for a list of these runtimes and more details.

### Build execution model

# Dependency Injection

Use dependencies when:

* They can't be declared in Pydantic validation and require additional logic
* The logic depends on external resources or could block in any other way
* Other dependencies need their results (it's a sub-dependency)
* The logic can be shared by multiple endpoints to do things like error early, authentication, etc.
* They need to handle cleanup (e.g., DB sessions, file handles), using dependencies with `yield`

# Path Parameters and Numeric Validations { #path-parameters-and-numeric-validations }

In the same way that you can declare more validations and metadata for query parameters with `Query`, you can declare the same type of validations and metadata for path parameters with `Path`.

## Import `Path` { #import-path }

First, import `Path` from `fastapi`, and import `Annotated`:

{* ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py hl[1,3] *}

    FESS_MAX_MEM=$FESS_HEAP_SIZE
fi

# External opensearch cluster
#SEARCH_ENGINE_HTTP_URL=http://localhost:9200
#FESS_DICTIONARY_PATH=/var/lib/opensearch/config/

# SSL truststore for certificate validation over https
#FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Djavax.net.ssl.trustStore=/tech/elastic/config/truststore.jks"
#FESS_JAVA_OPTS="$FESS_JAVA_OPTS -Djavax.net.ssl.trustStorePassword=changeit"

			}

			if data.valid && err != nil {
				t.Errorf("Error while verifying token: %T:%v", err, err)
			}

			if !data.valid && err == nil {
				t.Errorf("Invalid token passed validation")
			}

			if data.errors != 0 {
				_, ok := err.(*jwt.ValidationError)
				if !ok {
					t.Errorf("Expected *jwt.ValidationError, but got %#v instead", err)
				}
			}
		})
	}

```Python
item: Item
```

...and with that single declaration you get:

* Editor support, including:
    * Completion.
    * Type checks.
* Validation of data:
    * Automatic and clear errors when the data is invalid.
    * Validation even for deeply nested JSON objects.

 *
 * <p>Features:
 * <ul>
 *   <li>Automatic initialization of GCS client</li>
 *   <li>Support for HEAD and GET operations</li>
 *   <li>Content length validation</li>
 *   <li>MIME type detection</li>
 *   <li>Handling of large files through temporary file storage</li>
 *   <li>Object metadata retrieval</li>
 *   <li>Directory listing capabilities</li>
 * </ul>
 *

- The `DeclarativeValidation` feature gate is enabled by default. When enabled, mismatches with existing hand written validation is reported via metrics.

So, even with the code above that doesn't use Pydantic explicitly, FastAPI is using Pydantic to convert those standard dataclasses to Pydantic's own flavor of dataclasses.

And of course, it supports the same:

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

- **XML Processing** (`org.codelibs.core.xml`) - XML DOM utilities, SAX parser helpers, and schema validation support
- **SQL Utilities** (`org.codelibs.core.sql`) - JDBC helper methods for result sets, prepared statements, and connection management