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relationalai.std.strings.join()

join(strings: Sequence[str|Producer], separator: str|Producer) -> Expression

Combines a sequence of strings into a single string using a specified separator. If strings or separator is a Producer, then join() acts as a filter and removes any non-string values from the sequence. Must be called in a rule or query context.

Parameters

Name	Type	Description
`strings`	Sequence of `str` or `Producer`	The sequence of strings to be joined.
`separator`	`str` or `Producer`	The separator to use between strings.

Returns

An Expression object.

Example

Use join() to combine strings with a specified separator:

import relationalai as rai
from relationalai.std import strings


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

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

with model.rule():
    Person.add(id=1).set(first_name="Alice", last_name="Smith")
    Person.add(id=2).set(first_name="Bob", last_name="Jones")
    Person.add(id=3).set(first_name="Invalid", last_name=-1)  # Non-string last name


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

# Create a full_name property by joining first_name and last_name with a space.
with model.rule():
    person = Person()
    person.set(full_name=strings.join([person.first_name, person.last_name], " "))

# Since join() filters out non-string values, the full_name property
# is not set for the person with id=3.
with model.query() as select:
    person = Person()
    response = select(person.id, person.full_name)

print(response.results)
#    id     full_name
# 0   1   Alice Smith
# 1   2     Bob Jones
# 2   3           NaN

See Also