t.Fatalf("Blog should has three tags after Replace")
	}

	// Delete
	DB.Model(&blog).Association("Tags").Delete(tag5)
	var tags3 []Tag
	DB.Model(&blog).Association("Tags").Find(&tags3)
	if !compareTags(tags3, []string{"tag6"}) {
		t.Fatalf("Should find 1 tags after Delete")
	}

	if DB.Model(&blog).Association("Tags").Count() != 1 {
		t.Fatalf("Blog should has three tags after Delete")
	}

 */
internal sealed class Tags {
  /**
   * Returns a tags instance that maps [key] to [value]. If [value] is null, this returns a tags
   * instance that does not have any mapping for [key].
   */
  abstract fun <T : Any> plus(
    key: KClass<T>,
    value: T?,
  ): Tags

  abstract operator fun <T : Any> get(key: KClass<T>): T?
}

/** An empty tags. This is always the tail of a [LinkedTags] chain. */

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

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

        // Test roles
        String[] roles = { "admin", "user" };
        item.setRoles(roles);

        readings2[1] = new String[] { "kensaku", "fuga" };
        String[] tags2 = new String[] { "tag3" };
        String[] roles2 = new String[] { SuggestConstants.DEFAULT_ROLE, "role4" };
        queryItems[1] = new SuggestItem(new String[] { "全文", "検索" }, readings2, new String[] { "content" }, 1, 0, -1, tags2, roles2, null,
                SuggestItem.Kind.DOCUMENT);

        assertNotNull(dataMap);
        assertTrue(dataMap.get("tags") instanceof List);
        @SuppressWarnings("unchecked")
        List<String> tags = (List<String>) dataMap.get("tags");
        assertEquals(3, tags.size());
        assertEquals("tag1", tags.get(0));
        assertEquals("tag2", tags.get(1));
        assertEquals("tag3", tags.get(2));
    }

        .plus(Boolean::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromEmpty() {
    val tags = EmptyTags.plus(String::class, null)
    assertThat(tags).isEqualTo(EmptyTags)
    assertThat(tags.toString()).isEqualTo("{}")
  }

  @Test
  fun removeAbsentFromNonEmpty() {
    val tags =
      EmptyTags

        List<String> fields = new ArrayList<>();
        fields.add("field1");
        List<String> tags = new ArrayList<>();
        tags.add("tag1");
        List<String> roles = new ArrayList<>();
        roles.add("role1");

        elevateWord = new ElevateWord(word, boost, readings, fields, tags, roles);

        // Check that we get the same references
        assertTrue(readings == elevateWord.getReadings());

	defer r.Unlock()
	// Search of tag key already exists in tags
	var updated bool
	for _, tag := range r.tags {
		if tag.Key == key {
			tag.Val = val
			updated = true
			break
		}
	}
	if !updated {
		// Append to the end of tags list
		r.tags = append(r.tags, KeyVal{key, val})
	}
	return r
}

// GetTags - returns the user defined tags
func (r *ReqInfo) GetTags() []KeyVal {
	if r == nil {

                                    "required": ["name", "tags"],
                                    "type": "object",
                                    "properties": {
                                        "name": {"title": "Name", "type": "string"},
                                        "tags": {
                                            "title": "Tags",
                                            "type": "array",

/// tip

You don't have to add metadata for all the tags that you use.

///

### Use your tags { #use-your-tags }

Use the `tags` parameter with your *path operations* (and `APIRouter`s) to assign them to different tags:

{* ../../docs_src/metadata/tutorial004_py39.py hl[21,26] *}

/// info

Read more about tags in [Path Operation Configuration](path-operation-configuration.md#tags){.internal-link target=_blank}.

///