Values

A native data type that may be stored in an SQLite database.

A type that can be initialized directly from a column in an SQLite result row.

The implementation should use one of the sqlite_column_X() functions documented at Result Values From A Query.

For example, the implementation for Int64 is:

extension Int64: ColumnConvertible {
    public init(_ stmt: SQLitePreparedStatement, column idx: Int32) {
       self = sqlite3_column_int64(stmt, idx)
    }
}

A type that can bind its value directly to a parameter in an SQLite statement.

The implementation should use one of the sqlite_bind_X() functions documented at Binding Values To Prepared Statements.

For example, the implementation for Int64 is:

extension Int64: ParameterBindable {
    public func bind(to stmt: SQLitePreparedStatement, parameter idx: Int32) throws {
        guard sqlite3_bind_int64(stmt, idx, self) == SQLITE_OK else {
            throw SQLiteError("Error binding Int64 \(self) to parameter \(idx)", takingDescriptionFromStatement: stmt)
        }
    }
}

A type that may be serialized to and deserialized from a database.

This is a more general method for database storage than ParameterBindable and ColumnConvertible because it allows types to customize their behavior based on the database value’s data type. A database value’s data type is the value returned by the sqlite3_column_type() before any type conversions have taken place.

For example, NSNumber can choose what to store in the database based on the boxed value:

extension NSNumber: DatabaseSerializable {
    public func serialized() -> DatabaseValue {
        switch CFNumberGetType(self as CFNumber) {
        case .sInt8Type, .sInt16Type, .sInt32Type, .charType, .shortType, .intType,
             .sInt64Type, .longType, .longLongType, .cfIndexType, .nsIntegerType:
            return DatabaseValue.integer(self.int64Value)

        case .float32Type, .float64Type, .floatType, .doubleType, .cgFloatType:
            return DatabaseValue.float(self.doubleValue)
        }
    }

    public static func deserialize(from value: DatabaseValue) throws -> Self {
        switch value {
        case .integer(let i):
            return self.init(value: i)
        case .float(let f):
            return self.init(value: f)
        default:
            throw DatabaseError("\(value) is not a number")
        }
    }
}