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Optional Extension Reference
Optional
extension Optional where Wrapped: DatabaseValueConvertibleextension Optional where Wrapped: DatabaseValueConvertible & Hashableextension Optional where Wrapped: DatabaseValueConvertible & StatementColumnConvertibleextension Optional where Wrapped: DatabaseValueConvertible & StatementColumnConvertible & HashableSwift’s Optional comes with built-in methods that allow to fetch cursors and arrays of optional DatabaseValueConvertible:
try Optional<String>.fetchCursor(db, sql: "SELECT name FROM ...", arguments:...) // Cursor of String?
try Optional<String>.fetchAll(db, sql: "SELECT name FROM ...", arguments:...) // [String?]
let statement = try db.makeStatement(sql: "SELECT name FROM ...")
try Optional<String>.fetchCursor(statement, arguments:...) // Cursor of String?
try Optional<String>.fetchAll(statement, arguments:...) // [String?]
DatabaseValueConvertible is adopted by Bool, Int, String, etc.
-
Returns a cursor over optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchCursor(statement) // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> NullableDatabaseValueCursor<Wrapped>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchAll(statement) // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> [Wrapped?]Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An array of optional values.
-
Returns a set of optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchSet(statement) // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> Set<Wrapped?>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A set of optional values.
-
Returns a cursor over optional values fetched from an SQL query.
let names = try Optional<String>.fetchCursor(db, sql: "SELECT name FROM ...") // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> NullableDatabaseValueCursor<Wrapped>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from an SQL query.
let names = try String.fetchAll(db, sql: "SELECT name FROM ...") // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> [Wrapped?]Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An array of optional values.
-
Returns a set of optional values fetched from an SQL query.
let names = try String.fetchSet(db, sql: "SELECT name FROM ...") // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> Set<Wrapped?>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A set of optional values.
-
Returns a cursor over optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchCursor(db, request) // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor<R: FetchRequest>(_ db: Database, _ request: R) throws -> NullableDatabaseValueCursor<Wrapped>Parameters
dbA database connection.
requestA FetchRequest.
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchAll(db, request) // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll<R>(_ db: Database, _ request: R) throws -> [Wrapped?] where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An array of optional values.
-
Returns a set of optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchSet(db, request) // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet<R>(_ db: Database, _ request: R) throws -> Set<Wrapped?> where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
A set of optional values.
-
Returns a cursor over optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchCursor(statement) // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> FastNullableDatabaseValueCursor<Wrapped>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchAll(statement) // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> [Wrapped?]Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An array of optional values.
-
Returns a set of optional values fetched from a prepared statement.
let statement = try db.makeStatement(sql: "SELECT name FROM ...") let names = try Optional<String>.fetchSet(statement) // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet( _ statement: Statement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> Set<Wrapped?>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A set of optional values.
-
Returns a cursor over optional values fetched from an SQL query.
let names = try Optional<String>.fetchCursor(db, sql: "SELECT name FROM ...") // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> FastNullableDatabaseValueCursor<Wrapped>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from an SQL query.
let names = try Optional<String>.fetchAll(db, sql: "SELECT name FROM ...") // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> [Wrapped?]Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An array of optional values.
-
Returns a set of optional values fetched from an SQL query.
let names = try Optional<String>.fetchSet(db, sql: "SELECT name FROM ...") // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> Set<Wrapped?>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A set of optional values.
-
Returns a cursor over optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchCursor(db, request) // Cursor of String? while let name = try names.next() { // String? ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispatch queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor<R: FetchRequest>(_ db: Database, _ request: R) throws -> FastNullableDatabaseValueCursor<Wrapped>Parameters
dbA database connection.
requestA FetchRequest.
Return Value
A cursor over fetched optional values.
-
Returns an array of optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchAll(db, request) // [String?]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll<R>(_ db: Database, _ request: R) throws -> [Wrapped?] where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An array of optional values.
-
Returns a set of optional values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try Optional<String>.fetchSet(db, request) // Set<String?>Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchSet<R>(_ db: Database, _ request: R) throws -> Set<Wrapped?> where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
A set of optional values.