View on GitHub
Install in Dash
DatabaseValueConvertible Protocol Reference
DatabaseValueConvertible
public protocol DatabaseValueConvertible : SQLExpressibleTypes that adopt DatabaseValueConvertible can be initialized from database values.
The protocol comes with built-in methods that allow to fetch cursors, arrays, or single values:
try String.fetchCursor(db, sql: "SELECT name FROM ...", arguments:...) // Cursor of String
try String.fetchAll(db, sql: "SELECT name FROM ...", arguments:...) // [String]
try String.fetchOne(db, sql: "SELECT name FROM ...", arguments:...) // String?
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...")
try String.fetchCursor(statement, arguments:...) // Cursor of String
try String.fetchAll(statement, arguments:...) // [String]
try String.fetchOne(statement, arguments:...) // String?
DatabaseValueConvertible is adopted by Bool, Int, String, etc.
-
Returns a value that can be stored in the database.
Declaration
Swift
var databaseValue: DatabaseValue { get } -
Returns a value initialized from dbValue, if possible.
Declaration
Swift
static func fromDatabaseValue(_ dbValue: DatabaseValue) -> Self?
-
fetchCursor(_:Extension methodarguments: adapter: ) Returns a cursor over values fetched from a prepared statement.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let names = try 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 dispath queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> DatabaseValueCursor<Self>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension methodarguments: adapter: ) Returns an array of values fetched from a prepared statement.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let names = try String.fetchAll(statement) // [String]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> [Self]Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An array.
-
fetchOne(_:Extension methodarguments: adapter: ) Returns a single value fetched from a prepared statement.
The result is nil if the query returns no row, or if no value can be extracted from the first row.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let name = try String.fetchOne(statement) // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> Self?Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An optional value.
-
fetchCursor(_:Extension methodsql: arguments: adapter: ) Returns a cursor over values fetched from an SQL query.
let names = try String.fetchCursor(db, sql: "SELECT name FROM ...") // Cursor of String while let name = try name.next() { // String ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispath 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 -> DatabaseValueCursor<Self>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension methodsql: arguments: adapter: ) Returns an array of 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 -> [Self]Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An array.
-
fetchOne(_:Extension methodsql: arguments: adapter: ) Returns a single value fetched from an SQL query.
The result is nil if the query returns no row, or if no value can be extracted from the first row.
let name = try String.fetchOne(db, sql: "SELECT name FROM ...") // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> Self?Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An optional value.
-
fetchCursor(_:Extension method_: ) Returns a cursor over values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try String.fetchCursor(db, request) // Cursor of String while let name = try name.next() { // String ... }If the database is modified during the cursor iteration, the remaining elements are undefined.
The cursor must be iterated in a protected dispath queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor<R>(_ db: Database, _ request: R) throws -> DatabaseValueCursor<Self> where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension method_: ) Returns an array of values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try 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 -> [Self] where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An array.
-
fetchOne(_:Extension method_: ) Returns a single value fetched from a fetch request.
The result is nil if the query returns no row, or if no value can be extracted from the first row.
let request = Player.filter(key: 1).select(Column("name")) let name = try String.fetchOne(db, request) // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne<R>(_ db: Database, _ request: R) throws -> Self? where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An optional value.
-
fetchCursor(_:Extension methodarguments: adapter: ) Returns a cursor over values fetched from a prepared statement.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let names = try 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 dispath queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> FastDatabaseValueCursor<Self>Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension methodarguments: adapter: ) Returns an array of values fetched from a prepared statement.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let names = try String.fetchAll(statement) // [String]Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchAll( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> [Self]Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An array of values.
-
fetchOne(_:Extension methodarguments: adapter: ) Returns a single value fetched from a prepared statement.
let statement = try db.makeSelectStatement(sql: "SELECT name FROM ...") let name = try String.fetchOne(statement) // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne( _ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil) throws -> Self?Parameters
statementThe statement to run.
argumentsOptional statement arguments.
adapterOptional RowAdapter
Return Value
An optional value.
-
fetchCursor(_:Extension methodsql: arguments: adapter: ) Returns a cursor over values fetched from an SQL query.
let names = try 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 dispath 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 -> FastDatabaseValueCursor<Self>Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension methodsql: arguments: adapter: ) Returns an array of 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 -> [Self]Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An array of values.
-
fetchOne(_:Extension methodsql: arguments: adapter: ) Returns a single value fetched from an SQL query.
let name = try String.fetchOne(db, sql: "SELECT name FROM ...") // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne( _ db: Database, sql: String, arguments: StatementArguments = StatementArguments(), adapter: RowAdapter? = nil) throws -> Self?Parameters
dbA database connection.
sqlAn SQL query.
argumentsStatement arguments.
adapterOptional RowAdapter
Return Value
An optional value.
-
fetchCursor(_:Extension method_: ) Returns a cursor over values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try 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 dispath queue.
Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchCursor<R: FetchRequest>(_ db: Database, _ request: R) throws -> FastDatabaseValueCursor<Self>Parameters
dbA database connection.
requestA FetchRequest.
Return Value
A cursor over fetched values.
-
fetchAll(_:Extension method_: ) Returns an array of values fetched from a fetch request.
let request = Player.select(Column("name")) let names = try 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 -> [Self] where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An array of values.
-
fetchOne(_:Extension method_: ) Returns a single value fetched from a fetch request.
let request = Player.filter(key: 1).select(Column("name")) let name = try String.fetchOne(db, request) // String?Throws
A DatabaseError is thrown whenever an SQLite error occurs.Declaration
Swift
public static func fetchOne<R>(_ db: Database, _ request: R) throws -> Self? where R : FetchRequestParameters
dbA database connection.
requestA FetchRequest.
Return Value
An optional value.
-
databaseValueDefault implementationDefault Implementation
Returns a value that can be stored in the database.
Declaration
Swift
public var databaseValue: DatabaseValue { get } -
fromDatabaseValue(_:Default implementation) Default Implementation
Returns a value initialized from dbValue, if possible.
Declaration
Swift
public static func fromDatabaseValue(_ dbValue: DatabaseValue) -> Self?
-
databaseValueDefault implementationDefault Implementation
Returns a value that can be stored in the database.
Declaration
Swift
public var databaseValue: DatabaseValue { get } -
fromDatabaseValue(_:Default implementation) Default Implementation
Returns a value initialized from dbValue, if possible.
Declaration
Swift
public static func fromDatabaseValue(_ dbValue: DatabaseValue) -> Self?