rule()#

relationalai.Model
Model.rule(dynamic: bool = False) -> Context

Creates a rule Context.

Parameters#

NameTypeDescription
dynamicboolWhether or not the rule is dynamic. Dynamic queries support Python control flow as macros. See Context for more information.

Returns#

A Context object.

Example#

Model.rule() is a context manager and should be called in a with statement.

Rules describe objects in a model:

import relationalai as rai

model = rai.Model("people")
Person = model.Type("Person")
Adult = model.Type("Adult")

# Add people to the model.
with model.rule():
    alex = Person.add(name="Alex", age=19)
    bob = Person.add(name="Bob", age=47)
    carol = Person.add(name="Carol", age=17)

# All people that are 18 years old or older are adults.
with model.rule() as select:
    person = Person()
    person.age >= 18
    person.set(Adult)

You write rules using RelationalAI’s declarative query builder syntax. See Getting Started with RelationalAI for an introduction to writing rules and queries.

Note that you may pass data from your Python application into a rule:

min_adult_age = 21

with model.rule() as select:
    person = Person()
    person.age >= min_adult_age
    person.set(Adult)

By default, rules do not support while and for loops and other flow control tools such as if and match. You can enable flow control by setting the dynamic parameter to True, which lets you use Python flow control as a macro to build up a rule dynamically:

with model.rule(dynamic=True):
    person = Person()
    for i in range(3):
        person.set(count=i)

See Also#