ContextFetchableRecord: a new realm of records for GRDB.swift

ContextFetchableRecord.swift

// A replication of the convenience fetching methods of FetchableRecord,
// built for another record protocol: ContextFetchableRecord

protocol ContextFetchableRecord {
    associatedtype Context
    init(row: Row, context: Context)
}

extension ContextFetchableRecord {
    
    // MARK: Fetching From SelectStatement
    
    static func fetchCursor(_ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> MapCursor<RowCursor, Self> {
        return try Row.fetchCursor(statement, arguments: arguments, adapter: adapter).map {
            Self(row: $0, context: context)
        }
    }
    
    static func fetchAll(_ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> [Self] {
        return try Array(fetchCursor(statement, arguments: arguments, adapter: adapter, context: context))
    }
    
    static func fetchOne(_ statement: SelectStatement, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> Self? {
        return try fetchCursor(statement, arguments: arguments, adapter: adapter, context: context).next()
    }
}

extension ContextFetchableRecord {
    
    // MARK: Fetching From SQL
    
    static func fetchCursor(_ db: Database, _ sql: String, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> MapCursor<RowCursor, Self> {
        return try SQLRequest<Self>(sql, arguments: arguments, adapter: adapter).fetchCursor(db, context: context)
    }
    
    static func fetchAll(_ db: Database, _ sql: String, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> [Self] {
        return try SQLRequest<Self>(sql, arguments: arguments, adapter: adapter).fetchAll(db, context: context)
    }
    
    static func fetchOne(_ db: Database, _ sql: String, arguments: StatementArguments? = nil, adapter: RowAdapter? = nil, context: Context) throws -> Self? {
        return try SQLRequest<Self>(sql, arguments: arguments, adapter: adapter).fetchOne(db, context: context)
    }
}

extension ContextFetchableRecord {
    
    // MARK: Fetching From FetchRequest
    
    static func fetchCursor<R: FetchRequest>(_ db: Database, _ request: R, context: Context) throws -> MapCursor<RowCursor, Self> {
        let (statement, adapter) = try request.prepare(db)
        return try fetchCursor(statement, adapter: adapter, context: context)
    }
    
    static func fetchAll<R: FetchRequest>(_ db: Database, _ request: R, context: Context) throws -> [Self] {
        let (statement, adapter) = try request.prepare(db)
        return try fetchAll(statement, adapter: adapter, context: context)
    }
    
    static func fetchOne<R: FetchRequest>(_ db: Database, _ request: R, context: Context) throws -> Self? {
        let (statement, adapter) = try request.prepare(db)
        return try fetchOne(statement, adapter: adapter, context: context)
    }
}

extension FetchRequest where RowDecoder: ContextFetchableRecord {
    
    // MARK: Fetching Records
    
    func fetchCursor(_ db: Database, context: RowDecoder.Context) throws -> MapCursor<RowCursor, RowDecoder> {
        return try RowDecoder.fetchCursor(db, self, context: context)
    }
    
    func fetchAll(_ db: Database, context: RowDecoder.Context) throws -> [RowDecoder] {
        return try RowDecoder.fetchAll(db, self, context: context)
    }
    
    func fetchOne(_ db: Database, context: RowDecoder.Context) throws -> RowDecoder? {
        return try RowDecoder.fetchOne(db, self, context: context)
    }
}