Module `grainite_cl.api.value`

Classes

class Value (value: Any, b_value: Optional[bytes] = None)

Represents a typed value in Grainite. The underlying value may be of types int, float, str, bool, list, dict, bytes, None. Nested, arbitrarily complex, objects are supported via lists and dicts.

A typed value is understood by Grainite across supported languages. The lexicographical comparator on the serialized bytes will offer the same result as a comparison for the Type itself.

A typed value may be used anywhere, including for Grain Keys, Values, Map Keys or Map Values. However, it's recommended to use Key objects to represent Keys, as they add some additional constraints on the contents of a key.

You can construct a Value object in the following ways:

>>> Value(<value>)
>>> Value.of(<value1>, <value2>, ...) # Passing multiple arguments constructs a compound value
>>> Value.deserialize(<bytes>)

Use Value.is_null() to check if the underlying value is null. After retrieving a Value object from Grainite, use the appropriate as_long / as_double / as_string / as_bool / as_list / as_dict / as_bytes method to retrieve the underlying object, corresponding to the underyling object's type.

Subclasses

Class variables

var NULLVALUE: This is equivalent to None

Static methods

def deserialize(b_value: bytes) ‑> Value: Returns a Value object from the given bytes
def max_key() ‑> Value: Represents the largest possible (non-compound) Value.

Useful when fetching a range of Values or Keys.
def min_key() ‑> Value: Represents the smallest possible (non-compound) Value.

Useful when fetching a range of Values or Keys.
def of(*args) ‑> Value: Used to construct a compound Value object from multiple arguments provided as underlying values. This function is also used by Key to construct compound keys.

Methods

def as_bytes(self) ‑> bytes: Return the underlying value as bytes
def as_dict(self) ‑> Dict: Return the underlying value as a dict
def as_double(self) ‑> float: Return the underlying value as a float
def as_list(self) ‑> List: Return the underlying value as a list
def as_long(self) ‑> int: Return the underlying value as an int
def as_string(self) ‑> str: Return the underlying value as a str
def get_bytes(self) ‑> bytes: Return the underlying value as bytes
def is_null(self) ‑> bool: Returns True if the underlying value is Value.NULLVALUE or None
def last_key_for_prefix(self) ‑> Value: Produces a Value that by literal order would be immediately after the last possible key with the current Value as a prefix.

Useful when performing a range scan to compute the ending key.
def size(self) ‑> int: Return the length of the underlying value when represented as bytes