Files
CoreStore/Sources/BaseDataTransaction+Querying.swift
2024-09-10 11:14:39 +09:00

651 lines
30 KiB
Swift

//
// BaseDataTransaction+Querying.swift
// CoreStore
//
// Copyright © 2018 John Rommel Estropia
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.
//
import Foundation
import CoreData
// MARK: - DataTransaction
extension BaseDataTransaction: FetchableSource, QueryableSource {
/**
Deletes all `DynamicObject`s that satisfy the specified `DeleteClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter deleteClauses: a series of `DeleteClause` instances for the delete request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the number of `DynamicObject`s deleted
*/
@discardableResult
public func deleteAll<O>(
_ from: From<O>,
_ deleteClauses: DeleteClause...
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to delete from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.deleteAll(from, deleteClauses)
}
/**
Deletes all `DynamicObject`s that satisfy the specified `DeleteClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter deleteClauses: a series of `DeleteClause` instances for the delete request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the number of `DynamicObject`s deleted
*/
@discardableResult
public func deleteAll<O>(
_ from: From<O>,
_ deleteClauses: [DeleteClause]
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to delete from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.deleteAll(from, deleteClauses)
}
/**
Deletes all `DynamicObject`s that satisfy the specified conditions.
```
transaction.deleteAll(From<Person>().where(\.age > 50))
```
- parameter clauseChain: a `FetchChainableBuilderType` clause chain created from a `From` clause
- returns: the number of `DynamicObject`s deleted
*/
@discardableResult
public func deleteAll<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to delete from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.deleteAll(
clauseChain.from,
clauseChain.fetchClauses
)
}
// MARK: FetchableSource
/**
Fetches the `DynamicObject` instance in the transaction's context from a reference created from a transaction or from a different managed object context.
- parameter object: a reference to the object created/fetched outside the transaction
- returns: the `DynamicObject` instance if the object exists in the transaction, or `nil` if not found.
*/
public func fetchExisting<O: DynamicObject>(
_ object: O
) -> O? {
return self.context.fetchExisting(object)
}
/**
Fetches the `DynamicObject` instance in the transaction's context from an `NSManagedObjectID`.
- parameter objectID: the `NSManagedObjectID` for the object
- returns: the `DynamicObject` instance if the object exists in the transaction, or `nil` if not found.
*/
public func fetchExisting<O: DynamicObject>(
_ objectID: NSManagedObjectID
) -> O? {
return self.context.fetchExisting(objectID)
}
/**
Fetches the `DynamicObject` instances in the transaction's context from references created from a transaction or from a different managed object context.
- parameter objects: an array of `DynamicObject`s created/fetched outside the transaction
- returns: the `DynamicObject` array for objects that exists in the transaction
*/
public func fetchExisting<O: DynamicObject, S: Sequence>(
_ objects: S
) -> [O] where S.Iterator.Element == O {
return self.context.fetchExisting(objects)
}
/**
Fetches the `DynamicObject` instances in the transaction's context from a list of `NSManagedObjectID`.
- parameter objectIDs: the `NSManagedObjectID` array for the objects
- returns: the `DynamicObject` array for objects that exists in the transaction
*/
public func fetchExisting<O: DynamicObject, S: Sequence>(
_ objectIDs: S
) -> [O] where S.Iterator.Element == NSManagedObjectID {
return self.context.fetchExisting(objectIDs)
}
/**
Fetches the first `DynamicObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the first `DynamicObject` instance that satisfies the specified `FetchClause`s, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchOne<O>(
_ from: From<O>,
_ fetchClauses: FetchClause...
) throws(CoreStoreError) -> O? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchOne(from, fetchClauses)
}
/**
Fetches the first `DynamicObject` instance that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the first `DynamicObject` instance that satisfies the specified `FetchClause`s, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchOne<O>(
_ from: From<O>,
_ fetchClauses: [FetchClause]
) throws(CoreStoreError) -> O? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchOne(from, fetchClauses)
}
/**
Fetches the first `DynamicObject` instance that satisfies the specified `FetchChainableBuilderType` built from a chain of clauses.
```
let youngestTeen = transaction.fetchOne(
From<MyPersonEntity>()
.where(\.age > 18)
.orderBy(.ascending(\.age))
)
```
- parameter clauseChain: a `FetchChainableBuilderType` built from a chain of clauses
- returns: the first `DynamicObject` instance that satisfies the specified `FetchChainableBuilderType`, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchOne<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> B.ObjectType? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchOne(clauseChain)
}
/**
Fetches all `DynamicObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: all `DynamicObject` instances that satisfy the specified `FetchClause`s, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchAll<O>(
_ from: From<O>,
_ fetchClauses: FetchClause...
) throws(CoreStoreError) -> [O] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchAll(from, fetchClauses)
}
/**
Fetches all `DynamicObject` instances that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: all `DynamicObject` instances that satisfy the specified `FetchClause`s, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchAll<O>(
_ from: From<O>,
_ fetchClauses: [FetchClause]
) throws(CoreStoreError) -> [O] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchAll(from, fetchClauses)
}
/**
Fetches all `DynamicObject` instances that satisfy the specified `FetchChainableBuilderType` built from a chain of clauses.
```
let people = transaction.fetchAll(
From<MyPersonEntity>()
.where(\.age > 18)
.orderBy(.ascending(\.age))
)
```
- parameter clauseChain: a `FetchChainableBuilderType` built from a chain of clauses
- returns: all `DynamicObject` instances that satisfy the specified `FetchChainableBuilderType`, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchAll<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> [B.ObjectType] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchAll(clauseChain)
}
/**
Fetches the number of `DynamicObject`s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the number of `DynamicObject`s that satisfy the specified `FetchClause`s
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchCount<O>(
_ from: From<O>,
_ fetchClauses: FetchClause...
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchCount(from, fetchClauses)
}
/**
Fetches the number of `DynamicObject`s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the number of `DynamicObject`s that satisfy the specified `FetchClause`s
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchCount<O>(
_ from: From<O>,
_ fetchClauses: [FetchClause]
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchCount(from, fetchClauses)
}
/**
Fetches the number of `DynamicObject`s that satisfy the specified `FetchChainableBuilderType` built from a chain of clauses.
```
let numberOfAdults = transaction.fetchCount(
From<MyPersonEntity>()
.where(\.age > 18)
.orderBy(.ascending(\.age))
)
```
- parameter clauseChain: a `FetchChainableBuilderType` built from a chain of clauses
- returns: the number of `DynamicObject`s that satisfy the specified `FetchChainableBuilderType`
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchCount<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> Int {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchCount(clauseChain)
}
/**
Fetches the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchClause`s, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectID<O>(
_ from: From<O>,
_ fetchClauses: FetchClause...
) throws(CoreStoreError) -> NSManagedObjectID? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectID(from, fetchClauses)
}
/**
Fetches the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchClause`s, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectID<O>(
_ from: From<O>,
_ fetchClauses: [FetchClause]
) throws(CoreStoreError) -> NSManagedObjectID? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectID(from, fetchClauses)
}
/**
Fetches the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchChainableBuilderType` built from a chain of clauses.
```
let youngestTeenID = transaction.fetchObjectID(
From<MyPersonEntity>()
.where(\.age > 18)
.orderBy(.ascending(\.age))
)
```
- parameter clauseChain: a `FetchChainableBuilderType` built from a chain of clauses
- returns: the `NSManagedObjectID` for the first `DynamicObject` that satisfies the specified `FetchChainableBuilderType`, or `nil` if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectID<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> NSManagedObjectID? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectID(clauseChain)
}
/**
Fetches the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchClause`s, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectIDs<O>(
_ from: From<O>,
_ fetchClauses: FetchClause...
) throws(CoreStoreError) -> [NSManagedObjectID] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectIDs(from, fetchClauses)
}
/**
Fetches the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchClause`s. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- parameter from: a `From` clause indicating the entity type
- parameter fetchClauses: a series of `FetchClause` instances for the fetch request. Accepts `Where`, `OrderBy`, and `Tweak` clauses.
- returns: the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchClause`s, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectIDs<O>(
_ from: From<O>,
_ fetchClauses: [FetchClause]
) throws(CoreStoreError) -> [NSManagedObjectID] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectIDs(from, fetchClauses)
}
/**
Fetches the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchChainableBuilderType` built from a chain of clauses.
```
let idsOfAdults = transaction.fetchObjectIDs(
From<MyPersonEntity>()
.where(\.age > 18)
.orderBy(.ascending(\.age))
)
```
- parameter clauseChain: a `FetchChainableBuilderType` built from a chain of clauses
- returns: the `NSManagedObjectID` for all `DynamicObject`s that satisfy the specified `FetchChainableBuilderType`, or an empty array if no match was found
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func fetchObjectIDs<B: FetchChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> [NSManagedObjectID] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to fetch from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.fetchObjectIDs(clauseChain)
}
// MARK: QueryableSource
/**
Queries aggregate values as specified by the `QueryClause`s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
- parameter from: a `From` clause indicating the entity type
- parameter selectClause: a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
- parameter queryClauses: a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
- returns: the result of the the query, or `nil` if no match was found. The type of the return value is specified by the generic type of the `Select<U>` parameter.
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryValue<O, U: QueryableAttributeType>(
_ from: From<O>,
_ selectClause: Select<O, U>,
_ queryClauses: QueryClause...
) throws(CoreStoreError) -> U? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryValue(from, selectClause, queryClauses)
}
/**
Queries aggregate values or aggregates as specified by the `QueryClause`s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
- parameter from: a `From` clause indicating the entity type
- parameter selectClause: a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
- parameter queryClauses: a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
- returns: the result of the the query, or `nil` if no match was found. The type of the return value is specified by the generic type of the `Select<U>` parameter.
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryValue<O, U: QueryableAttributeType>(
_ from: From<O>,
_ selectClause: Select<O, U>,
_ queryClauses: [QueryClause]
) throws(CoreStoreError) -> U? {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryValue(from, selectClause, queryClauses)
}
/**
Queries a property value or aggregate as specified by the `QueryChainableBuilderType` built from a chain of clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
```
let averageAdultAge = transaction.queryValue(
From<MyPersonEntity>()
.select(Int.self, .average(\.age))
.where(\.age > 18)
)
```
- parameter clauseChain: a `QueryChainableBuilderType` indicating the property/aggregate to fetch and the series of queries for the request.
- returns: the result of the the query as specified by the `QueryChainableBuilderType`, or `nil` if no match was found.
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryValue<B: QueryChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> B.ResultType? where B.ResultType: QueryableAttributeType {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryValue(
clauseChain.from,
clauseChain.select,
clauseChain.queryClauses
)
}
/**
Queries a dictionary of attribute values as specified by the `QueryClause`s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
- parameter from: a `From` clause indicating the entity type
- parameter selectClause: a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
- parameter queryClauses: a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
- returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryAttributes<O>(
_ from: From<O>,
_ selectClause: Select<O, NSDictionary>,
_ queryClauses: QueryClause...
) throws(CoreStoreError) -> [[String: Any]] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryAttributes(from, selectClause, queryClauses)
}
/**
Queries a dictionary of attribute values as specified by the `QueryClause`s. Requires at least a `Select` clause, and optional `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
- parameter from: a `From` clause indicating the entity type
- parameter selectClause: a `Select<U>` clause indicating the properties to fetch, and with the generic type indicating the return type.
- parameter queryClauses: a series of `QueryClause` instances for the query request. Accepts `Where`, `OrderBy`, `GroupBy`, and `Tweak` clauses.
- returns: the result of the the query. The type of the return value is specified by the generic type of the `Select<U>` parameter.
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryAttributes<O>(
_ from: From<O>,
_ selectClause: Select<O, NSDictionary>,
_ queryClauses: [QueryClause]
) throws(CoreStoreError) -> [[String: Any]] {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryAttributes(from, selectClause, queryClauses)
}
/**
Queries a dictionary of attribute values or as specified by the `QueryChainableBuilderType` built from a chain of clauses.
A "query" differs from a "fetch" in that it only retrieves values already stored in the persistent store. As such, values from unsaved transactions or contexts will not be incorporated in the query result.
```
let results = dataStack.queryAttributes(
From<MyPersonEntity>()
.select(
NSDictionary.self,
.attribute(\.age, as: "age"),
.count(\.age, as: "numberOfPeople")
)
.groupBy(\.age)
)
for dictionary in results! {
let age = dictionary["age"] as! Int
let count = dictionary["numberOfPeople"] as! Int
print("There are \(count) people who are \(age) years old."
}
```
- parameter clauseChain: a `QueryChainableBuilderType` indicating the properties to fetch and the series of queries for the request.
- returns: the result of the the query as specified by the `QueryChainableBuilderType`
- throws: `CoreStoreError.persistentStoreNotFound` if the specified entity could not be found in any store's schema.
*/
public func queryAttributes<B: QueryChainableBuilderType>(
_ clauseChain: B
) throws(CoreStoreError) -> [[String: Any]] where B.ResultType == NSDictionary {
Internals.assert(
self.isRunningInAllowedQueue(),
"Attempted to query from a \(Internals.typeName(self)) outside its designated queue."
)
return try self.context.queryAttributes(
clauseChain.from,
clauseChain.select,
clauseChain.queryClauses
)
}
// MARK: FetchableSource, QueryableSource
/**
The internal `NSManagedObjectContext` managed by this instance. Using this context directly should typically be avoided, and is provided by CoreStore only for extremely specialized cases.
*/
public func unsafeContext() -> NSManagedObjectContext {
return self.context
}
}