# JSON Compatible Encoder { #json-compatible-encoder }

There are some cases where you might need to convert a data type (like a Pydantic model) to something compatible with JSON (like a `dict`, `list`, etc).

For example, if you need to store it in a database.

For that, **FastAPI** provides a `jsonable_encoder()` function.

## Using the `jsonable_encoder` { #using-the-jsonable-encoder }

 * <strong>not</strong> equal to {@code key2}, it is <strong>not</strong> guaranteed that {@code
 * striped.get(key1) != striped.get(key2)}; the elements might nevertheless be mapped to the same
 * lock. The lower the number of stripes, the higher the probability of this happening.
 *
 * <p>There are three flavors of this class: {@code Striped<Lock>}, {@code Striped<Semaphore>}, and

certificate.

The trusted roots don't need to be the same for client and server when using client authentication.
Clients might rely on the platform certificates and servers might use a private
organization-specific certificate authority.

By default `HeldCertificate` instances expire after 24 hours. Use `duration()` to adjust.

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	// If format.json is available and request sent the right disk-id, we allow the request
	return true
}

// checkID - check if the disk-id in the request corresponds to the underlying disk.
func (s *storageRESTServer) checkID(wantID string) bool {
	if s.getStorage() == nil {
		return false
	}
	if wantID == "" {
		// Request sent empty disk-id, we allow the request
		// as the peer might be coming up and trying to read format.json

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			objSize: 2 << 10,
			sizeFilter: BatchJobSizeFilter{
				UpperBound: 10 << 20,
				LowerBound: 1 << 20,
			},
			want: false,
		},
		{
			// 11MiB > 10 MiB -> out of range from right
			objSize: 11 << 20,
			sizeFilter: BatchJobSizeFilter{
				UpperBound: 10 << 20,
				LowerBound: 1 << 20,
			},
			want: false,
		},
		{
			//  2MiB < 10MiB -> in range
			objSize: 2 << 20,

<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Forbid Extra Headers { #forbid-extra-headers }

In some special use cases (probably not very common), you might want to **restrict** the headers that you want to receive.

You can use Pydantic's model configuration to `forbid` any `extra` fields:

{* ../../docs_src/header_param_models/tutorial002_an_py310.py hl[10] *}

    assertEquals("null=null", entry(NK, NV).toString());
  }

  public void testEquals() {
    Entry<String, Integer> foo1 = entry("foo", 1);
    // Explicitly call `equals`; `assertEquals` might return fast
    assertTrue(foo1.equals(foo1));
    assertEquals(control("foo", 1), foo1);
    assertEquals(control("bar", 2), entry("bar", 2));
    assertFalse(control("foo", 1).equals(entry("foo", 2)));

  }

  private static final class NullFriendlyComparator<T> implements Comparator<T>, Serializable {
    @Override
    public int compare(T left, T right) {
      return String.valueOf(left).compareTo(String.valueOf(right));
    }
  }