In fact, in some cases, it will even have **two JSON Schemas** in OpenAPI for the same Pydantic model, for input and output, depending on if they have **default values**.

Let's see how that works and how to change it if you need to do that.

## Pydantic Models for Input and Output { #pydantic-models-for-input-and-output }

Let's say you have a Pydantic model with default values, like this one:

		{strings.Repeat("Ꙁ", 64) + "Ꚁ", '䚀', -1},  // 'Ꚁ' and '䚀' share the same last two bytes

		// 4 bytes
		{"𡌀", '𡌀', 0},
		{"a", '𡌀', -1},
		{"  𡌀", '𡌀', 2},
		{"  a", '𡌀', -1},
		{strings.Repeat("𡋀", 64) + "𡌀", '𡌀', 256}, // test cutover
		{strings.Repeat("𡋀", 64) + "𡌀", '𣌀', -1},  // '𡌀' and '𣌀' share the same last two bytes

		// RuneError should match any invalid UTF-8 byte sequence.

import java.util.Map.Entry;
import java.util.Set;
import java.util.Spliterator;
import java.util.function.BiConsumer;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Multimap} whose contents will never change, with many other important properties
 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableMultimap} as a type (as with

public class AbstractSetTester<E> extends AbstractCollectionTester<E> {
  /*
   * Previously we had a field named set that was initialized to the value of
   * collection in setUp(), but that caused problems when a tester changed the
   * value of set or collection but not both.
   */
  protected final Set<E> getSet() {
    return (Set<E>) collection;
  }

func TestSetAndGet(t *testing.T) {
	if value, ok := DB.Set("hello", "world").Get("hello"); !ok {
		t.Errorf("Should be able to get setting after set")
	} else if value.(string) != "world" {
		t.Errorf("Set value should not be changed")
	}

	if _, ok := DB.Get("non_existing"); ok {
		t.Errorf("Get non existing key should return error")
	}

In many cases your application could need some external settings or configurations, for example secret keys, database credentials, credentials for email services, etc.

Most of these settings are variable (can change), like database URLs. And many could be sensitive, like secrets.

For this reason it's common to provide them in environment variables that are read by the application.

/// tip

## Using the `jsonable_encoder` in a `Response` { #using-the-jsonable-encoder-in-a-response }

Because **FastAPI** doesn't make any changes to a `Response` you return, you have to make sure its contents are ready for it.

import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;

/**
 * This annotation tags types that are part of an experimental API.
 * Classes or methods annotated with this annotation may be changed / removed without notice.
 *
 * @since 4.0.0
 */
@Experimental
@Documented
@Retention(RetentionPolicy.CLASS)

TFCI_BAZEL_COMMON_ARGS="--repo_env=HERMETIC_PYTHON_VERSION=$TFCI_PYTHON_VERSION --repo_env=USE_PYWRAP_RULES=True --config release_arm64_linux"
TFCI_BAZEL_TARGET_SELECTING_CONFIG_PREFIX=linux_arm64
# Note: this is not set to "--cpu", because that changes the package name
# to tensorflow_cpu. These ARM builds are supposed to have the name "tensorflow"
# despite lacking Nvidia CUDA support.
TFCI_BUILD_PIP_PACKAGE_WHEEL_NAME_ARG="--repo_env=WHEEL_NAME=tensorflow"

import java.util.function.BinaryOperator;
import java.util.function.Function;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * A {@link Table} whose contents will never change, with many other important properties detailed
 * at {@link ImmutableCollection}.
 *
 * <p>See the Guava User Guide article on <a href=