Struct MetadataStore

Source

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

Expand description

A lightweight key-value metadata store backed by a HashMap.

MetadataStore is designed for storing arbitrary string metadata such as task attributes, labels, annotations, headers, or contextual information.

Keys are unique within the store. Attempting to insert a duplicate key returns a MetadataError::DuplicateKey error.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("request_id", "abc-123")?;
metadata.insert("environment", "production")?;

assert_eq!(
    metadata.get("request_id"),
    Some(&"abc-123".to_string())
);

assert!(metadata.contains_key("environment"));

Implementations§

Source §

impl MetadataStore

Source

pub fn new() -> Self

Creates an empty MetadataStore.

§Examples

let metadata = MetadataStore::new();

assert_eq!(metadata.iter().count(), 0);

Source

pub fn insert<K, V>(&mut self, key: K, value: V) -> Result<(), MetadataError>
where K: Into<String>, V: Into<String>,

Inserts a key-value pair into the store.

Returns an error if the key already exists.

§Errors

Returns MetadataError::DuplicateKey if the provided key is already present in the store.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("region", "us-east-1")?;

assert_eq!(
    metadata.get("region"),
    Some(&"us-east-1".to_string())
);

Duplicate keys are rejected:

let mut metadata = MetadataStore::new();

metadata.insert("service", "api")?;

let err = metadata.insert("service", "worker").unwrap_err();

assert_eq!(
    err,
    MetadataError::DuplicateKey("service".to_string())
);

Source

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

Returns a reference to the value corresponding to the given key.

Returns None if the key does not exist.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("version", "1.0")?;

assert_eq!(
    metadata.get("version"),
    Some(&"1.0".to_string())
);

assert_eq!(metadata.get("missing"), None);

Source

pub fn remove(&mut self, key: &str) -> Option<String>

Removes a key from the store, returning the stored value if it existed.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("token", "secret")?;

assert_eq!(
    metadata.remove("token"),
    Some("secret".to_string())
);

assert!(!metadata.contains_key("token"));

Source

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

Returns true if the store contains the specified key.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("owner", "alice")?;

assert!(metadata.contains_key("owner"));
assert!(!metadata.contains_key("missing"));

Source

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

Returns an iterator over all key-value pairs in the store.

The iterator yields (&String, &String) pairs.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("a", "1")?;
metadata.insert("b", "2")?;

let items: Vec<_> = metadata.iter().collect();

assert_eq!(items.len(), 2);

Source

pub fn into_inner(self) -> HashMap<String, String>

Consumes the store and returns the underlying HashMap.

§Examples

let mut metadata = MetadataStore::new();

metadata.insert("key", "value")?;

let inner = metadata.into_inner();

assert_eq!(
    inner.get("key"),
    Some(&"value".to_string())
);