Struct Metadata 

pub struct Metadata(/* private fields */);

An immutable, ordered map of metadata keys to Values.

Build one from a BTreeMap with From, or collect it from an iterator of (String, Value) pairs. Read it with get, len, is_empty, and iter. There are no setters — to change metadata, build a new value.

Examples

use iqdb_types::{Metadata, Value};

let meta: Metadata = [
    ("title".to_string(), Value::String("intro".to_string())),
    ("year".to_string(), Value::Int(2026)),
]
.into_iter()
.collect();

assert_eq!(meta.len(), 2);
assert_eq!(meta.get("year"), Some(&Value::Int(2026)));
assert_eq!(meta.get("missing"), None);

Implementations

impl Metadata

pub fn get(&self, key: &str) -> Option<&Value>

Returns the value for key, or None if the key is absent.

Examples

use iqdb_types::{Metadata, Value};

let meta: Metadata =
    [("year".to_string(), Value::Int(2026))].into_iter().collect();
assert_eq!(meta.get("year"), Some(&Value::Int(2026)));
assert_eq!(meta.get("nope"), None);

pub fn len(&self) -> usize

Returns the number of entries.

Examples

use iqdb_types::{Metadata, Value};

let meta: Metadata =
    [("a".to_string(), Value::Null)].into_iter().collect();
assert_eq!(meta.len(), 1);

pub fn is_empty(&self) -> bool

Returns true if there are no entries.

Examples

use iqdb_types::Metadata;

assert!(Metadata::default().is_empty());

pub fn iter(&self) -> Iter<'_, String, Value>

Returns an iterator over the entries in key order.

Examples

use iqdb_types::{Metadata, Value};

let meta: Metadata = [
    ("b".to_string(), Value::Int(2)),
    ("a".to_string(), Value::Int(1)),
]
.into_iter()
.collect();

// BTreeMap iterates in key order.
let keys: Vec<&String> = meta.iter().map(|(key, _)| key).collect();
assert_eq!(keys, vec!["a", "b"]);

Trait Implementations

impl Clone for Metadata

fn clone(&self) -> Metadata

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Metadata

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Metadata

fn default() -> Metadata

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Metadata

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<BTreeMap<String, Value>> for Metadata

fn from(map: BTreeMap<String, Value>) -> Self

Converts to this type from the input type.

impl FromIterator<(String, Value)> for Metadata

fn from_iter<I: IntoIterator<Item = (String, Value)>>(iter: I) -> Self

Creates a value from an iterator.

impl PartialEq for Metadata

fn eq(&self, other: &Metadata) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Metadata

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Metadata