Struct Metadata 

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

Key → value metadata, stored as JSON values internally.

Converts to/from WIT list<tuple<string, list<u8>>> (CBOR) at the boundary.

Implementations

impl Metadata

pub fn new() -> Self

pub fn insert(&mut self, key: impl Into<String>, value: impl Into<Value>)

Insert a value. Overwrites any existing entry for the key.

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

Get a value by key.

pub fn get_as<T: DeserializeOwned>(&self, key: &str) -> Option<T>

Get a value by key, deserializing into a typed value.

pub fn contains_key(&self, key: &str) -> bool

Check if a key exists.

pub fn is_empty(&self) -> bool

Returns true if there are no entries.

pub fn iter(&self) -> impl Iterator<Item = (&String, &Value)>

Iterate over key-value pairs.

pub fn len(&self) -> usize

Number of entries.

pub fn extend(&mut self, other: Metadata)

Merge all entries from other into self. Entries in other overwrite existing keys.

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 From<Metadata> for Value

Convert to a JSON object value (consuming).

fn from(m: Metadata) -> Self

Converts to this type from the input type.

impl From<Metadata> for Vec<(String, Vec<u8>)>

Convert to WIT metadata (CBOR-encoded values).

fn from(m: Metadata) -> Self

Converts to this type from the input type.

impl From<Value> for Metadata

Convert from a JSON object value. Non-object values produce empty metadata.

fn from(value: Value) -> Self

Converts to this type from the input type.

impl From<Vec<(String, Vec<u8>)>> for Metadata

Convert from WIT metadata (CBOR-encoded values).

fn from(v: Vec<(String, Vec<u8>)>) -> Self

Converts to this type from the input type.