The filter query parameter is a percent-encoded JSON object conforming to ../schemas/filter.schema.json. Field names are RFC 6901 JSON Pointers into a resource representation. Values are JSON literals and retain their JSON types.
Operators#
eq,ne: equality and inequality.gt,gte,lt,lte: ordered comparison.in,nin: membership; operand MUST be an array.contains: string substring or array membership.starts_with,ends_with: string comparison.exists: field-presence test; operand MUST be boolean.
Implementations advertise the supported subset globally and per resource.
Boolean Form#
Field predicates in the same object are ANDed. Multiple operators on one field are also ANDed. $and, $or, and $not provide explicit composition.
json{
"$and": [
{"/status": {"eq": "active"}},
{"/temperature": {"gte": 20, "lt": 30}},
{"$or": [
{"/site": {"in": ["north", "west"]}},
{"/priority": {"eq": true}}
]}
]
}
Comparisons MUST follow the type declared by the resource representation's JSON Schema. There is no implicit conversion between strings, numbers, or booleans. String operations are case-sensitive Unicode code-point comparisons unless the resource advertises another collation in its description.
Filtering affects which records are returned, but does not alter their shape. Use fields for projection. A server MUST evaluate authorization before filtering and MUST NOT reveal inaccessible field values through errors.
For event subscriptions, predicates are evaluated against full authorized resource state, not projected HTTP fields. The transition rules in websocket.md determine whether pre-change state, post-change state, or both are evaluated.