# Query Parameter Models { #query-parameter-models }

If you have a group of **query parameters** that are related, you can create a **Pydantic model** to declare them.

This would allow you to **re-use the model** in **multiple places** and also to declare validations and metadata for all the parameters at once. 😎

/// note

This is supported since FastAPI version `0.115.0`. 🤓

///

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 }

Let's imagine that you have a database `fake_db` that only receives JSON compatible data.

For example, it doesn't receive `datetime` objects, as those are not compatible with JSON.

./mvnw clean install --projects '!guava-testlib,!guava-tests,!guava-bom' -Dmaven.test.skip=true -Dmaven.javadoc.skip=true -f android

# We run this separately so that its change to the default toolchain doesn't affect anything else.
# (And we run it after the main build so that that build has already downloaded Java 11 if necessary.)
./mvnw --projects '!guava-testlib,!guava-tests,!guava-bom,!guava-gwt' initialize -P print-java-11-home

    .sslSocketFactory(clientCertificates.sslSocketFactory(), clientCertificates.trustManager())
    .build();
```

With a server that holds a certificate and a client that trusts it we have enough for an HTTPS
handshake. The best part of this example is that we don't need to make our test code insecure with a
a fake `HostnameVerifier` or `X509TrustManager`.

Certificate Authorities
-----------------------

          private final char[] unknown = new char[] {'?'};

          @Override
          protected char[] escapeUnsafe(char c) {
            return unknown;
          }
        };
    EscaperAsserts.assertBasic(replacingEscaper);

    // Replacements are applied first regardless of whether the character is in
    // the safe range or not ('&' is a safe char while '\t' and '\n' are not).

/**
 * Creates temporary files and directories whose permissions are restricted to the current user or,
 * in the case of Android, the current app. If that is not possible (as is the case under the very
 * old Android Ice Cream Sandwich release), then this class throws an exception instead of creating
 * a file or directory that would be more accessible.
 */
@J2ktIncompatible
@GwtIncompatible
@J2ObjCIncompatible
abstract class TempFileCreator {

        // and a file that is READONLY, HIDDEN, and SYSTEM
        when(mockFile.getAttributes()).thenReturn(SmbFile.ATTR_READONLY | SmbFile.ATTR_HIDDEN | SmbFile.ATTR_SYSTEM);

        // When calling accept
        // Then it should be accepted because the READONLY attribute is present
        assertTrue(dosFileFilter.accept(mockFile));
    }

    /**

    exec.shutdown();
    exec.awaitTermination(100, MILLISECONDS);
  }

  /**
   * Tests that all listeners complete, even if they were added before or after the future was
   * finishing. Also acts as a concurrency test to make sure the locking is done correctly when a
   * future is finishing so that no listeners can be lost.
   */
  public void testAllListenersCompleteSuccessfully()

                    corresponding JSON.
                * Filtering: the JSON sent to the client will only contain the data
                    (fields) defined in the `response_model`. If you returned an object
                    that contains an attribute `password` but the `response_model` does
                    not include that field, the JSON sent to the client would not have

   * values by applying the remapping function. The remapping function accepts the map's existing
   * value for that part of the range and the given value. It returns the value to be associated
   * with that part of the map, or it returns {@code null} to clear that part of the map.
   *
   * <p>Any parts of the range not already present in this map are mapped to the specified value,