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relationalai.std.strings.String()

String(item: Producer) -> Expression

Filters values produced by a Producer to only include strings. Must be called in a rule or query context.

Parameters

Name	Type	Description
`item`	`Producer`	The Producer object to filter.

Returns

An Expression object.

Example

Use String() to filter string values:

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")  # id is a string.


# ========
# EXAMPLES
# ========

# Get people whose id is a string.
with model.query() as select:
    person = Person()
    strings.String(person.id)
    response = select(person.id, person.name)

print(response.results)
#   id name
# 0  1  Bob


# Get people whose id is not a string.
with model.query() as select:
    person = Person()
    with model.not_found():
        strings.String(person.id)
    response = select(person.id, person.name)

print(response.results)
#   id  name
# 0  2 Alice

See Also