replace()#

relationalai.std.strings
#replace(string: str|Producer, old: str|Producer, new: str|Producer) -> Expression

Replaces all occurrences of a substring in a string. If any of the arguments are Producer objects, replace() acts as a filter and removes non-string values from the producer. Must be called in a rule or query context.

Parameters#

NameTypeDescription
stringstr or ProducerA string or a producer that produces string values.
oldstr or ProducerThe substring to replace.
newstr or ProducerThe substring to replace old with.

Returns#

An Expression object.

Example#

#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(name="Alice")
    Person.add(id=2).set(name="Bob")
    Person.add(id=3).set(name=-1)  # Non-string name


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

# Set a new_name property equal to the name property with all occurrences of
# "ice" replaced with "icia".
with model.rule():
    person = Person()
    person.set(new_name=strings.replace(person.name, "ice", "icia"))

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

print(response.results)
#    id   name new_name
# 0   1  Alice   Alicia
# 1   2    Bob      Bob
# 2   3     -1      NaN

See Also#