Metadata Class Reference

Public Member Functions
None	__init__ (self)
	Initialize an empty metadata container.
None	set_value_by_name (self, str key, AllowedTypes value)
	Store a value using a string-based key.
None	remove_entry_by_name (self, str key)
	Removes the entry using a string-based name.
bool	has_entry_by_name (self, str key)
	Check if a string key is present in the metadata.
Any	try_get_value_by_name (self, str key)
	Retrieve a value by string key, returning None if not found.
T	get_value_by_name (self, Type[T] expected_type, str key)
	Retrieve the value for a key and validate that it is of the expected type.
None	set_value_by_key (self, MetadataKey key, Any value)
	Store a value using a strongly typed metadata key.
bool	has_entry_by_key (self, MetadataKey key)
	Check if a strongly typed metadata key is present and matches the expected type.
Any	get_value_by_key (self, MetadataKey key)
	Retrieve the value of a strongly typed metadata key.
List[str]	get_key_names (self)
	Returns a list of metadata key names.
bool	__eq__ (self, Any other)
	Check if two metadata are equal.
bool	__ne__ (self, Any other)
	Check if two metadata are not equal.
str	__str__ (self)
	Return a human-readable string of metadata keys and values.
str	__repr__ (self)
	Return an unambiguous string of the Metadata object.

Static Public Attributes
	AllowedTypes

Protected Attributes
dict	_data = {}

Detailed Description

A type-safe container for metadata key-value pairs.

This class provides a flexible mechanism for storing and retrieving metadata:

• Arbitrary runtime keys (string string_values).
• Strongly typed keys defined in a schema.

Values are stored in a Python dictionary but accessed with additional safety checks to ensure type correctness.

Example usage::

metadata = Metadata()
metadata.set_value_by_key(MetadataKey.DEVICE_FRAME_ID, 1)
print(metadata.get_value_by_key(MetadataKey.DEVICE_FRAME_ID)) # outputs: 1
print(metadata.has_entry_by_key(MetadataKey.DEVICE_FRAME_ID)) # outputs: True

Constructor & Destructor Documentation

__init__()

None __init__

(

self

)

Initialize an empty metadata container.

Member Function Documentation

__eq__()

bool __eq__	(		self,
		Any	other )

Check if two metadata are equal.

Parameters

other

Another Metadata object

Returns

True if metadata are equal, False otherwise

__ne__()

bool __ne__	(		self,
		Any	other )

Check if two metadata are not equal.

Parameters

other

Another metadata object

Returns

True if metadata are not equal, False otherwise

__repr__()

str __repr__

(

self

)

Return an unambiguous string of the Metadata object.

__str__()

str __str__

(

self

)

Return a human-readable string of metadata keys and values.

Example: { "DeviceFrameID": 42, "DeviceTimestamp": 1695472000, "custom_data": "xyz" }

get_key_names()

List[str] get_key_names

(

self

)

Returns a list of metadata key names.

Returns

A list of metadata key names

get_value_by_key()

Any get_value_by_key	(		self,
		MetadataKey	key )

Retrieve the value of a strongly typed metadata key.

Parameters

key	A MetadataKey object.

Exceptions

OutOfRangeException	If the key does not exist.
InvalidCastException	If the type does not match.

Returns

The stored value.

get_value_by_name()

T get_value_by_name	(		self,
		Type[T]	expected_type,
		str	key )

Retrieve the value for a key and validate that it is of the expected type.

Parameters

expected_type	The expected type of the stored value.
key	The metadata key.

Exceptions

OutOfRangeException	If the key does not exist.
InvalidCastException	If the stored type does not match.

Returns

The stored value cast to the expected type.

has_entry_by_key()

bool has_entry_by_key	(		self,
		MetadataKey	key )

Check if a strongly typed metadata key is present and matches the expected type.

Parameters

key	A MetadataKey object.

Returns

True if the key exists and type matches, False otherwise.

has_entry_by_name()

bool has_entry_by_name	(		self,
		str	key )

Check if a string key is present in the metadata.

Parameters

key	The metadata key.

Returns

True if the key exists, False otherwise.

remove_entry_by_name()

None remove_entry_by_name	(		self,
		str	key )

Removes the entry using a string-based name.

If the key does not exist, nothing happens.

Parameters

key	The metadata key to be removed.

set_value_by_key()

None set_value_by_key	(		self,
		MetadataKey	key,
		Any	value )

Store a value using a strongly typed metadata key.

Note that passing an empty list may result in a loss of information when the metadata object is passed to an image.

Parameters

key	A MetadataKey object containing key name and expected type.
value	The value to store.

Exceptions

InvalidCastException

If the value type does not match the trait type.

set_value_by_name()

None set_value_by_name	(		self,
		str	key,
		AllowedTypes	value )

Store a value using a string-based key.

Note that ignoring the allowed types for parameter value or passing an empty list may result in a loss of information when the metadata object is passed to an image.

Parameters

key	The key under which the value is stored.
value	Value to store.

try_get_value_by_name()

Any try_get_value_by_name	(		self,
		str	key )

Retrieve a value by string key, returning None if not found.

Parameters

key	The metadata key.

Returns

The stored value if found, otherwise None.

Field Documentation

_data

dict _data = {}

protected

AllowedTypes

AllowedTypes

static

Initial value:

=  Union[
        int, list[int],
        float, list[float],
        str, list[str],
        bool, list[bool]]