# Body - Fields

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`.

## Import `Field`

First, you have to import it:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}


/// warning

		cause:      err,
	}
}

func errIncorrectSQLFunctionArgumentType(err error) *s3Error {
	return &s3Error{
		code:       "IncorrectSqlFunctionArgumentType",
		message:    "Incorrect type of arguments in function call.",
		statusCode: 400,
		cause:      err,
	}
}

func errLikeInvalidInputs(err error) *s3Error {
	return &s3Error{
		code:       "LikeInvalidInputs",

    QUICK_FEEDBACK_LINUX_ONLY("Quick Feedback - Linux Only", "Run checks and functional tests (embedded executer, Linux)", "QuickFeedbackLinuxOnly"),
    QUICK_FEEDBACK("Quick Feedback", "Run checks and functional tests (embedded executer, Windows)", "QuickFeedback"),
    PULL_REQUEST_FEEDBACK("Pull Request Feedback", "Run various functional tests", "PullRequestFeedback"),

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.io.Serializable;
import java.util.Spliterator;
import java.util.function.Consumer;
import javax.annotation.CheckForNull;

/**
 * {@code keySet()} implementation for {@link ImmutableMap}.
 *
 * @author Jesse Wilson
 * @author Kevin Bourrillion
 */
@GwtCompatible(emulated = true)

// form `bytes=first-last` where first and last are zero-based byte
// offsets. See
// http://docs.aws.amazon.com/AmazonS3/latest/API/mpUploadUploadPartCopy.html
// for full details. This function treats an empty rangeString as
// referring to the whole resource.
func parseCopyPartRangeSpec(rangeString string) (hrange *HTTPRangeSpec, err error) {
	hrange, err = parseRequestRangeSpec(rangeString)
	if err != nil {

		s.DialAvgDuration = atomic.LoadUint64(&globalStats.tcpDialTotalDur) / v
		s.TTFBAvgDuration = atomic.LoadUint64(&globalStats.tcpTimeForFirstByteTotalDur) / v
	}
	return s
}

// Return a function which update the global stats related to tcp connections
func setupReqStatsUpdate(req *http.Request) (*http.Request, func()) {
	var dialStart, dialEnd int64
	start := time.Now()
	trace := &httptrace.ClientTrace{

<img src="/img/tutorial/body-fields/image02.png">

## Detalhes técnicos

/// warning | "Atenção"

Esses são detalhes muito técnicos sobre os padrões **JSON Schema** e **OpenAPI**.

Se as ideias explicadas acima já funcionam para você, isso pode ser o suficiente, e você provavelmente não precisa desses detalhes, fique à vontade para pular.

///

      final Iterable<F> fromIterable, final Function<? super F, ? extends T> function) {
    checkNotNull(fromIterable);
    checkNotNull(function);
    return new FluentIterable<T>() {
      @Override
      public Iterator<T> iterator() {
        return Iterators.transform(fromIterable.iterator(), function);
      }
    };
  }

  /**

	lockFileFailImmediately = 1

	// see https://msdn.microsoft.com/en-us/library/windows/desktop/ms681382(v=vs.85).aspx
	errLockViolation syscall.Errno = 0x21
)

// lockedOpenFile is an internal function.
func lockedOpenFile(path string, flag int, perm os.FileMode, lockType uint32) (*LockedFile, error) {
	f, err := Open(path, flag, perm)
	if err != nil {
		return nil, err
	}

    }
    return result;
  }

  // Helpers + main

  private byte runHashFunction(int reps, HashFunction hashFunction) {
    byte result = 0x01;
    // Trick the JVM to prevent it from using the hash function non-polymorphically
    result ^= Hashing.crc32().hashInt(reps).asBytes()[0];
    result ^= Hashing.adler32().hashInt(reps).asBytes()[0];
    result ^= Hashing.fingerprint2011().hashInt(reps).asBytes()[0];