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relationalai.std.strings.length()

length(string: str|Producer) -> Expression

Gets the length of a string. If string is a Producer, then length() acts as a filter and removes non-string values from the producer. Must be called in a rule or query context.

Parameters

Name	Type	Description
`string`	`Producer` or Python `str` object	A string or a producer that produces string values.

Returns

An Expression object.

Example

Use length() to get the length of a string:

import relationalai as rai
from relationalai.std import alias, strings


# =====
# SETUP
# =====

model = rai.Model("MyModel")
Person = model.Type("Person")

with model.rule():
    alice = Person.add(id=1).set(name="Alice")
    # Set a multi-valued hobbies property with a mix of string and non-string values.
    alice.hobbies.extend(["reading", "swimming", -1])


# =======
# EXAMPLE
# =======

with model.query() as select:
    person = Person()
    hobby = person.hobbies
    response = select(
        alias(hobby, "hobby_string"),
        alias(strings.length(hobby), "length")
    )

print(response.results)
#   hobby_string  length
# 0      reading       7
# 1     swimming       8

See Also