Operators

fastapi-filters supports a rich set of filter operators. Operators are automatically assigned to fields based on their Python type, but you can always customize them.

All Available Operators

Operator	Query Syntax	Description
eq	field[eq]=value	Equal to
ne	field[ne]=value	Not equal to
gt	field[gt]=value	Greater than
ge	field[ge]=value	Greater than or equal
lt	field[lt]=value	Less than
le	field[le]=value	Less than or equal
like	field[like]=value	SQL LIKE pattern match
ilike	field[ilike]=value	Case-insensitive LIKE
not_like	field[not_like]=value	Negated LIKE
not_ilike	field[not_ilike]=value	Negated case-insensitive LIKE
in	field[in]=a,b,c	Value in list
not_in	field[not_in]=a,b,c	Value not in list
is_null	field[is_null]=true	Is NULL / Is NOT NULL
overlap	field[overlap]=a,b,c	Arrays overlap
not_overlap	field[not_overlap]=a,b,c	Arrays do not overlap
contains	field[contains]=a,b,c	Array contains all values
not_contains	field[not_contains]=a,b,c	Array does not contain all values

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Auto-Generated Operators by Type

The library generates operators based on the field's Python type:

bool

Operators
eq, ne

int, float, date, datetime, timedelta

Operators
eq, ne, in, not_in, gt, ge, lt, le

str

Operators
eq, ne, in, not_in, like, ilike, not_like, not_ilike, gt, ge, lt, le

list[T] (Sequence types)

Operators
overlap, not_overlap, contains, not_contains

Optional[T] (T | None)

All operators for type T plus is_null.

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Operator Groups

The operators are organized into groups internally:

from fastapi_filters.operators import (
    BOOL_OPERATORS,      # eq, ne
    DEFAULT_OPERATORS,   # eq, ne, in, not_in
    NUM_OPERATORS,       # gt, ge, lt, le
    SEQ_OPERATORS,       # overlap, not_overlap, contains, not_contains
    STR_OPERATORS,       # like, ilike, not_like, not_ilike
)

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FilterOperator Enum

All operators are defined in the FilterOperator enum:

from fastapi_filters import FilterOperator

# Use in FilterField definitions
from fastapi_filters import FilterField, FilterSet


class UserFilters(FilterSet):
    name: FilterField[str] = FilterField(
        operators=[FilterOperator.eq, FilterOperator.ilike],
    )

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Query Parameter Format

Filters are passed as query parameters using bracket notation:

GET /users?name[eq]=John&age[gt]=25&email[in]=a@test.com,b@test.com

• field[operator]=value -- explicit operator
• CSV values for list operators: field[in]=a,b,c
• Boolean values for is_null: field[is_null]=true or field[is_null]=false