Logical Operators

Logical Operators#

EQL provides intuitive ways to combine multiple constraints using logical operators. These allow you to build complex filters beyond simple attribute checks.

The Conjunction (AND)#

You can combine conditions using the and_() operator or by passing multiple arguments to .where(). Both methods are equivalent.

1. Multiple conditions in .where()#

# Select robots that are named 'R2D2' AND have battery > 50
query = entity(r).where(r.name == "R2D2", r.battery > 50)

2. Using the and_() operator#

# This produces the same result
query = entity(r).where(and_(r.name == "R2D2", r.battery > 50))

Hint

Using multiple arguments in .where() is generally cleaner for simple (unnested) conjunctions.

The Disjunction (OR)#

Use the or_() operator to specify that at least one of the conditions must be met.

# Select robots that are either 'R2D2' OR have battery < 10
query = entity(r).where(or_(r.name == "R2D2", r.battery < 10))

The Negation (NOT)#

The not_() operator inverts a condition. It returns results that do not satisfy the specified constraint.

# Select all robots EXCEPT those named 'R2D2'
query = entity(r).where(not_(r.name == "R2D2"))

Note

Negation can be particularly useful for “anti-joins” or excluding specific subsets from your results.

Full Example: Complex Logic#

Let’s build a query that combines all these operators.

from dataclasses import dataclass
from krrood.entity_query_language.factories import variable, entity, an, Symbol, not_

@dataclass
class ExampleRobot(Symbol):
    name: str
    battery: int
    online: bool

robots = [
    ExampleRobot("R2D2", 100, True),
    ExampleRobot("C3PO", 20, False),
    ExampleRobot("BB8", 80, True),
    ExampleRobot("Gonk", 5, True)
]

r = variable(ExampleRobot, domain=robots)

# We want robots that are (ONLINE and (battery > 50)) OR (NOT ONLINE and battery < 30)
query = an(entity(r).where(
    or_(and_(r.online , r.battery > 50), and_(not_(r.online) , r.battery < 30))
))

for robot in query.evaluate():
    print(f"Robot: {robot.name} (Online: {robot.online}, Battery: {robot.battery})")

API Reference#