TransactionMetadata

class cometa.auxiliary_data.transaction_metadata.TransactionMetadata(ptr=None)[source]

Bases: object

Represents transaction metadata as a map of labels to metadatum values.

Transaction metadata in Cardano is organized as a map where keys are unsigned 64-bit integers (labels) and values are Metadatum objects. Common labels include 721 for NFT metadata (CIP-25).

Example

>>> metadata = TransactionMetadata()
>>> metadata.insert(721, Metadatum.from_string("NFT metadata"))

__init__(ptr=None)[source]

Return type:: None

__enter__()[source]

Return type:: TransactionMetadata

__exit__(exc_type, exc_val, exc_tb)[source]

Return type:: None

__repr__()[source]

Return repr(self).

Return type:: str

classmethod from_cbor(reader)[source]

Deserializes TransactionMetadata from CBOR data.

Parameters:: reader (CborReader) – A CborReader positioned at the metadata data.
Returns:: A new TransactionMetadata deserialized from the CBOR data.
Raises:: CardanoError – If deserialization fails.
Return type:: TransactionMetadata

insert(label, value)[source]

Inserts or updates a metadatum entry with the given label.

Parameters:

label (int) – The metadata label (unsigned 64-bit integer).
value (Metadatum) – The metadatum value to associate with the label.

Raises:

CardanoError – If insertion fails.

Return type:

None

Example

>>> metadata.insert(721, nft_metadatum)

get(label)[source]

Retrieves the metadatum associated with a label.

Parameters:: label (int) – The metadata label to look up.
Returns:: The Metadatum associated with the label.
Raises:: CardanoError – If the label is not found or retrieval fails.
Return type:: Metadatum

Example

>>> nft_meta = metadata.get(721)

get_key_at(index)[source]

Retrieves the label at a specific index.

Parameters:

index (int) – The index of the label to retrieve.

Returns:

The label at the specified index.

Raises:

CardanoError – If retrieval fails.
IndexError – If index is out of bounds.

Return type:

int

get_value_at(index)[source]

Retrieves the metadatum at a specific index.

Parameters:

index (int) – The index of the metadatum to retrieve.

Returns:

The Metadatum at the specified index.

Raises:

CardanoError – If retrieval fails.
IndexError – If index is out of bounds.

Return type:

Metadatum

get_key_value_at(index)[source]

Retrieves the key-value pair at a specific index.

Parameters:

index (int) – The index of the key-value pair to retrieve.

Returns:

A tuple containing the label (int) and Metadatum at the specified index.

Raises:

CardanoError – If retrieval fails.
IndexError – If index is out of bounds.

Return type:

tuple[int, Metadatum]

get_keys()[source]

Retrieves all keys (labels) from the metadata.

Returns:: A MetadatumLabelList containing all labels in the metadata.
Raises:: CardanoError – If retrieval fails.
Return type:: MetadatumLabelList

to_cbor(writer)[source]

Serializes the transaction metadata to CBOR format.

Parameters:: writer (CborWriter) – A CborWriter to write the serialized data to.
Raises:: CardanoError – If serialization fails.
Return type:: None

__len__()[source]

Returns the number of metadata entries.

Return type:: int

__iter__()[source]

Iterates over all (label, metadatum) pairs.

Return type:: Iterator[Tuple[int, Metadatum]]

__contains__(label)[source]

Checks if a label exists in the metadata.

Parameters:: label (int)
Return type:: bool

__getitem__(label)[source]

Gets a metadatum by label using bracket notation.

Parameters:: label (int)
Return type:: Metadatum

__setitem__(label, value)[source]

Sets a metadatum by label using bracket notation.

Parameters:

label (int)
value (Metadatum)

Return type:

None

to_cip116_json(writer)[source]

Serializes this object to CIP-116 compliant JSON.

Parameters:: writer (JsonWriter) – The JsonWriter to write the JSON to.
Raises:: CardanoError – If serialization fails.
Return type:: None