How to Filter and Query¶

Python operators¶

The most natural way to filter — use Python comparison operators directly:

City.state == "CA"
City.population > 1_000_000
City.population <= 500_000
City.state != "NY"

Named methods¶

For Firestore operators that don't have a Python symbol:

City.regions.array_contains("west_coast")
City.regions.array_contains_any(["west_coast", "east_coast"])
City.country.is_in(["USA", "Japan"])
City.country.not_in(["China"])

Explicit equivalents

Every operator also has a named method: .eq(), .ne(), .gt(), .gte(), .lt(), .lte(). Useful when you need to pass the method as a callback.

Compose with & and |¶

(City.state == "CA") & (City.population > 1_000_000)
(City.state == "CA") | (City.state == "NY")

Or use And / Or explicitly:

from cendry import And, Or

Or(
    City.state == "CA",
    And(City.country == "Japan", City.population > 1_000_000),
)

Use parentheses

& and | have higher precedence than == in Python. Always wrap comparisons in parentheses.

Chain filters on Query¶

Build up filters incrementally — each call returns a new immutable Query:

query = (
    ctx.select(City)
    .filter(City.state == "CA")
    .filter(City.population > 500_000)
)

Also accepts a list:

query = ctx.select(City).filter([
    City.state == "CA",
    City.population > 500_000,
])

Use FieldFilter directly¶

For raw Firestore filters when you need them:

from cendry import FieldFilter

ctx.select(City, FieldFilter("state", "==", "CA"))

Operators reference¶

Operator	Python	Method
`==`	`City.state == "CA"`	`.eq("CA")`
`!=`	`City.state != "CA"`	`.ne("CA")`
`>`	`City.pop > 100`	`.gt(100)`
`>=`	`City.pop >= 100`	`.gte(100)`
`<`	`City.pop < 100`	`.lt(100)`
`<=`	`City.pop <= 100`	`.lte(100)`
`array-contains`	—	`.array_contains(v)`
`array-contains-any`	—	`.array_contains_any([...])`
`in`	—	`.is_in([...])`
`not-in`	—	`.not_in([...])`