FetchRequest

The type that tells how fetched database rows should be interpreted.

This method is deprecated. Use makePreparedRequest(_:forSingleResult:) instead.

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

Returns a PreparedRequest that is ready to be executed.

Returns the number of rows fetched by the request.

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

Adopting types can refine this method in order to use more efficient SQL.

A cursor over fetched values.

let request: ... // Some FetchRequest that fetches String
let strings = try request.fetchCursor(db) // Cursor of String
while let string = try strings.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.

An array of fetched values.

let request: ... // Some FetchRequest that fetches String
let strings = try request.fetchAll(db) // [String]

The first fetched value.

The result is nil if the request returns no row, or if no value can be extracted from the first row.

let request: ... // Some FetchRequest that fetches String
let string = try request.fetchOne(db) // String?

A cursor over fetched optional values.

let request: ... // Some FetchRequest that fetches Optional<String>
let strings = try request.fetchCursor(db) // Cursor of String?
while let string = try strings.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.

An array of fetched optional values.

let request: ... // Some FetchRequest that fetches Optional<String>
let strings = try request.fetchAll(db) // [String?]

Returns an adapted request.

Returns the database region that the request looks into.

This default implementation returns a region built from the statement returned by the prepare method.

A cursor over fetched rows.

let request: ... // Some FetchRequest that fetches Row
let rows = try request.fetchCursor(db) // RowCursor
while let row = try rows.next() {  // Row
    let id: Int64 = row[0]
    let name: String = row[1]
}

Fetched rows are reused during the cursor iteration: don’t turn a row cursor into an array with Array(rows) or rows.filter { ... } since you would not get the distinct rows you expect. Use Row.fetchAll(...) instead.

For the same reason, make sure you make a copy whenever you extract a row for later use: row.copy().

If the database is modified during the cursor iteration, the remaining elements are undefined.

The cursor must be iterated in a protected dispath queue.

An array of fetched rows.

let request: ... // Some FetchRequest that fetches Row
let rows = try request.fetchAll(db)

The first fetched row.

let request: ... // Some FetchRequest that fetches Row
let row = try request.fetchOne(db)

A cursor over fetched values.

let request: ... // Some FetchRequest that fetches String
let strings = try request.fetchCursor(db) // Cursor of String
while let string = try strings.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.

An array of fetched values.

let request: ... // Some FetchRequest that fetches String
let strings = try request.fetchAll(db) // [String]

The first fetched value.

The result is nil if the request returns no row, or if no value can be extracted from the first row.

let request: ... // Some FetchRequest that fetches String
let string = try request.fetchOne(db) // String?

A cursor over fetched optional values.

let request: ... // Some FetchRequest that fetches Optional<String>
let strings = try request.fetchCursor(db) // Cursor of String?
while let string = try strings.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.

An array of fetched optional values.

let request: ... // Some FetchRequest that fetches Optional<String>
let strings = try request.fetchAll(db) // [String?]

A cursor over fetched records.

let request: ... // Some FetchRequest that fetches Player
let players = try request.fetchCursor(db) // Cursor of Player
while let player = try players.next() {   // Player
    ...
}

If the database is modified during the cursor iteration, the remaining elements are undefined.

The cursor must be iterated in a protected dispath queue.

An array of fetched records.

let request: ... // Some FetchRequest that fetches Player
let players = try request.fetchAll(db) // [Player]

The first fetched record.

let request: ... // Some FetchRequest that fetches Player
let player = try request.fetchOne(db) // Player?

Creates a ValueObservation which observes request, and notifies its count whenever it is modified by a database transaction.

For example:

let request = Player.all()
let observation = request.observationForCount()

let observer = try observation.start(in: dbQueue) { count: Int in
    print("Number of players has changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies fresh values whenever the request is modified by a database transaction.

For example:

let request = Player.select(Column("name"), as: String.self)
let observation = request.observationForAll()

let observer = try observation.start(in: dbQueue) { names: [String] in
    print("Player names have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies a fresh value whenever the request is modified by a database transaction.

For example:

let request = Player.select(max(Column("score")), as: Int.self)
let observation = request.observationForFirst()

let observer = try observation.start(in: dbQueue) { maxScore: Int? in
    print("Maximum score has changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies fresh values whenever the request is modified by a database transaction.

For example:

let request = Player.select(Column("name"), as: Optional<String>.self)
let observation = request.observationForAll()

let observer = try observation.start(in: dbQueue) { names: [String?] in
    print("Player names have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies fresh values whenever the request is modified by a database transaction.

For example:

let request = Player.select(Column("name"), as: Optional<String>.self)
let observation = request.observationForAll()

let observer = try observation.start(in: dbQueue) { names: [String?] in
    print("Player names have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies fresh records whenever the request is modified by a database transaction.

For example:

let request = Player.all()
let observation = request.observationForAll()

let observer = try observation.start(in: dbQueue) { players: [Player] in
    print("Players have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies a fresh record whenever the request is modified by a database transaction.

For example:

let request = Player.filter(key: 1)
let observation = request.observationForFirst()

let observer = try observation.start(in: dbQueue) { player: Player? in
    print("Player has changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies fresh rows whenever the request is modified by a database transaction.

For example:

let request = SQLRequest<Row>(sql: "SELECT * FROM player")
let observation = request.observationForAll()

let observer = try observation.start(in: dbQueue) { rows: [Row] in
    print("Players have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.

Creates a ValueObservation which observes request, and notifies a fresh row whenever the request is modified by a database transaction.

For example:

let request = SQLRequest<Row>(sql: "SELECT * FROM player WHERE id = ?", arguments: [1])
let observation = request.observationForFirst()

let observer = try observation.start(in: dbQueue) { row: Row? in
    print("Players have changed")
}

The returned observation has the default configuration:

• When started with the start(in:onError:onChange:) method, a fresh value is immediately notified on the main queue.
• Upon subsequent database changes, fresh values are notified on the main queue.

• The observation lasts until the observer returned by start is deallocated.