# Тіло — Поля { #body-fields }

Так само як ви можете оголошувати додаткову валідацію та метадані в параметрах *функції операції шляху* за допомогою `Query`, `Path` та `Body`, ви можете оголошувати валідацію та метадані всередині моделей Pydantic, використовуючи `Field` від Pydantic.

## Імпорт `Field` { #import-field }

Спочатку вам потрібно імпортувати це:

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


/// warning | Попередження

// JSON utilities with proper escaping
String escaped = JsonUtil.escape("Hello \"World\" with special chars");
String unescaped = JsonUtil.unescape(escaped);

// Text tokenization
Tokenizer tokenizer = new Tokenizer("field1,field2,field3", ",");
while (tokenizer.hasMoreTokens()) {
    String token = tokenizer.nextToken();
    // Process each token
}

// Decimal formatting

        Map<String, Object> source;
        while ((source = reader.read()) != null) {
            assertTrue(source.get("field1").toString().startsWith("test"));
            valueSet.add(source.get("field1").toString());
            count++;
        }
        assertEquals(num, count);
        assertEquals(num, valueSet.size());
    }

    @Test

        item.setReadings(newReadings);
        assertArrayEquals(newReadings, item.getReadings());

        // Test fields
        String[] fields = { "field1", "field2" };
        item.setFields(fields);
        assertArrayEquals(fields, item.getFields());

        // Test tags
        String[] tags = { "tag1", "tag2" };
        item.setTags(tags);

        assertTrue(result.contains("field1"));
        assertTrue(result.contains("exclude1"));
    }

    @Test
    public void test_getCacheKey_sorting() {
        String seed = "test_seed";
        String[] tags = { "zzz", "aaa", "mmm" };
        String[] roles = { "role3", "role1", "role2" };
        String[] fields = { "field3", "field1", "field2" };

   * identity equality of its Thread field so that the task field is only accessed by a single
   * thread.
   */
  private static final class ThreadConfinedTaskQueue {
    /**
     * This field is only used for identity comparisons with the current thread. Field assignments
     * are atomic, but do not provide happens-before ordering; however:
     *
     * <ul>

Bazı özel kullanım senaryolarında (muhtemelen çok yaygın değildir), form field'larını yalnızca Pydantic model'inde tanımlananlarla **sınırlamak** isteyebilirsiniz. Ve **fazladan** gelen field'ları **yasaklayabilirsiniz**.

/// note | Not

Bu özellik FastAPI `0.114.0` sürümünden itibaren desteklenmektedir. 🤓

///

        emptyGenerator = new EmptyGenerator();

        // Test adding conditions - this should work without container
        emptyGenerator.addCondition("field1", "pattern1");
        emptyGenerator.addCondition("field1", "pattern2");
        emptyGenerator.addCondition("field2", "pattern.*");

        // We can't test isTarget properly without container,
        // but we can verify conditions are added

    void testConstantsArePublicStaticFinal() {
        Field[] fields = SecurityInfo.class.getDeclaredFields();

        for (Field field : fields) {
            int modifiers = field.getModifiers();
            assertTrue(Modifier.isPublic(modifiers), "Field " + field.getName() + " should be public");
            assertTrue(Modifier.isStatic(modifiers), "Field " + field.getName() + " should be static");

        </field>
        <field>
          <name>exists</name>
          <version>1.0.0+</version>
          <type>String</type>
          <description>
            The name of the file that should exist to activate a profile. Please note, that missing and exists
            fields cannot be used together. Only one of them should be used at any one time.
          </description>
        </field>
      </fields>
    </class>