Initializergrdb 7.3.0GRDB

    init(_:argumentCount:pure:function:)

    Creates an SQL function.

    DatabaseFunction.swift:85
    init(_ name: String, argumentCount: Int? = nil, pure: Bool = false, function: @escaping ([DatabaseValue]) throws -> (any DatabaseValueConvertible)?)
    Mangled symbol
    s4GRDB16DatabaseFunctionC_13argumentCount4pure8functionACSS_SiSgSbAA0B16ValueConvertible_pSgSayAA0bH0VGYbKctcfc What are these?
    FNV24 hash
    4F80X

    Parameters

    name

    The function name.

    argumentCount

    The number of arguments of the function. If omitted, or nil, the function accepts any number of arguments.

    pure

    Whether the function is “pure”, which means that its results only depends on its inputs. When a function is pure, SQLite has the opportunity to perform additional optimizations. Default value is false.

    function

    A function that takes an array of DatabaseValue arguments, and returns an optional DatabaseValueConvertible such as Int, String, Date, etc. The array is guaranteed to have exactly argumentCount elements, provided argumentCount is not nil.

    For example:

    let succ = DatabaseFunction("succ", argumentCount: 1) { dbValues in
    guard let int = Int.fromDatabaseValue(dbValues[0]) else {
        return nil
    }
    return int + 1
}
let dbQueue = try DatabaseQueue()
try dbQueue.read { db in
    db.add(function: succ)
    try Int.fetchOne(db, sql: "SELECT succ(1)")! // 2
}

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