[Home](./index.md) > [@firebase/firestore](./firestore.md) > [lite](./firestore_lite.md) > [QueryConstraint](./firestore_lite.queryconstraint.md) ## QueryConstraint class A `QueryConstraint` is used to narrow the set of documents returned by a Firestore query. `QueryConstraint`s are created by invoking [where()](./firestore_.where.md), [orderBy()](./firestore_.orderby.md), [startAt()](./firestore_.startat.md), [startAfter()](./firestore_.startafter.md), , [endAt()](./firestore_.endat.md), [limit()](./firestore_.limit.md) or [limitToLast()](./firestore_.limittolast.md) and can then be passed to [query()](./firestore_.query.md) to create a new query instance that also contains this `QueryConstraint`. Signature: ```typescript export declare abstract class QueryConstraint ``` ## Properties | Property | Modifiers | Type | Description | | --- | --- | --- | --- | | [type](./firestore_lite.queryconstraint.type.md) | | [QueryConstraintType](./firestore_lite.queryconstrainttype.md) | The type of this query constraints |