EntityPropertyQuery

protocol · iOS 16.0+ · SDK 27.1

protocol EntityPropertyQuery : EntityQuery

An interface for locating entities by matching values against one or more of their properties. `EntityPropertyQuery` provides an ``EntityQuery`` with the ability to query instances according to its traits as they are modeled through query properties and their corresponding comparators. At runtime, ``EntityPropertyQuery/entities(matching:mode:sortedBy:limit:)`` receives an array of `ComparatorMappingType` instances - a type of your choice that represents the different comparator mappings given by the user - and is responsible for fetching entities matching those comparators. The `properties` property on a `EntityPropertyQuery` contains the set of ``EntityQueryProperty``s the query accepts. When declaring each property's set of supported ``EntityQueryComparator``s, you will supply a closure that will transform a runtime user-supplied value into an instance of `ComparatorMappingType`. The AppIntents runtime will invoke query comparator mapping closures for each comparator included in the user request, gather their output `ComparatorMappingType` values, and then invoke the `entities` function. It is then up to you to retrieve entities matching those comparators, using whichever backend (in-memory lookup, CoreData, remote network call, ...) suits your application. For example, consider the following simplified `AppEntity` for a photo: ``` class MyPhoto: AppEntity { @Property(title: "Date taken") let takenAt: Date @Property(title: "Tags") let tags: [String] } ``` The following example shows how you would build a `EntityPropertyQuery` that allows the user to query for photos taken: * Before a certain date * After a certain date * Containing a given tag In `entities` you want to retrieve photos through a network request, so you supply mapping closures returning `URLQueryItem` instances for each ``EntityQueryComparator``. Then you can use those `URLQueryItem` in `entities` to construct the correct `URL` to fetch entities. ``` struct MyPhotoQuery: EntityPropertyQuery { static var properties = QueryProperties { Property(\.$takenAt) { LessThanMapping { URLQueryItem(name: "takenBefore", value: $0) } GreaterThanMapping { URLQueryItem(name: "takenAfter": value: $0) } } Property(\.$tags) { ContainsComparator { URLQueryItem(name: "tagsContains", value: $0) } } } func entities( matching comparators: [URLQueryItem], mode: ComparatorMode, sortedBy: [Sort<MyPhoto>], limit: Int? ) async throws -> [MyPhoto] { let components = URLComponents() components.queryItems = comparators let url = components.url(relativeTo: "https://myphotosbackend.com/photos") return try await PhotosBackend.fetch(url: url) } } ```

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