Request

public protocol Request

The protocol for all types that define a way to fetch values from a database.

Requests can feed the fetching methods of any fetchable type (Row, value, record):

let request: Request = ...
try Row.fetchCursor(db, request) // DatabaseCursor<Row>
try String.fetchAll(db, request) // [String]
try Person.fetchOne(db, request) // Person?

  • A tuple that contains a prepared statement that is ready to be executed, and an eventual row adapter.

    Declaration

    Swift

    func prepare(_ db: Database) throws -> (SelectStatement, RowAdapter?)
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  • fetchCount(_:) Default implementation

    The number of rows fetched by the request.

    Default implementation builds a naive SQL query based on the statement returned by the prepare method: SELECT COUNT(*) FROM (...).

    Adopting types can refine this countRequest method and return more efficient SQL.

    Default Implementation

    The number of rows fetched by the request.

    This default implementation builds a naive SQL query based on the statement returned by the prepare method: SELECT COUNT(*) FROM (...).

    Declaration

    Swift

    func fetchCount(_ db: Database) throws -> Int

    Parameters

    db

    A database connection.
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  • asRequest(of:) Extension method

    Returns a TypedRequest bound to type T.

    The returned request can fetch if the type T is fetchable (Row, value, record).

    // minHeight in Double?
let minHeight = Person
    .select(min(heightColumn))
    .asRequest(of: Double.self)    // <--
    .fetchOne(db)

    Declaration

    Swift

    public func asRequest<T>(of type: T.Type) -> AnyTypedRequest<T>

    Parameters

    type

    The fetched type T

    Return Value

    A typed request bound to type T.

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  • adapted(_:) Extension method

    Returns an adapted request.

    Declaration

    Swift

    public func adapted(_ makeAdapter: @escaping (Database) throws -> RowAdapter) -> AnyRequest
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