SQLite Swift db.prepare Optional() in statement values

Question

In the SQLite Swift documentation there is reference to getting statement results directly. I have a lot of SQL queries prepared and I don't really want to refactor them. I would sooner use them as they are using db.prepare, as per below.

Statements with results may be iterated over.

let stmt = try db.prepare("SELECT id, email FROM users")
for row in stmt {
    print("id: \(row[0]), email: \(row[1])")
    // id: Optional(1), email: Optional("alice@mac.com")
}

The return values always have the "Optional()" around them. Is there a way we can just get the raw row values back without this?

Ahmad · Answer 1 · 2015-11-16T20:41:16.870

2

Unwrap the values using ! after the variable as @stephencelis said:

let stmt = try db.prepare("SELECT id, email FROM users")
for row in stmt {
    print("id: \(row[0]!), email: \(row[1]!)")
}

edited Nov 16 '15 at 20:41

answered Nov 16 '15 at 20:34

Ahmad

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1

if my statement was "SELECT * from users". you know how to get columnName along with value in loop? – Lokesh Chowdary Jun 09 '17 at 08:23

Gwendal Roué · Answer 2 · 2017-03-20T06:36:37.023

1

You may want to use https://github.com/groue/GRDB.swift. It lets you extract optionals or non-optionals, just as you wish:

for row in Row.fetch(db, "SELECT id, email FROM users") {
    let id: Int64 = row.value(atIndex: 0)
    let email: String = row.value(atIndex: 1)
    print(id, email)
}

edited Mar 20 '17 at 06:36

answered Nov 24 '15 at 18:06

Gwendal Roué

3,949
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score 0 · Answer 3 · answered Nov 09 '15 at 12:03

The type-safe API lets you declare expressions of non-optional types that, when pulled back from a statement, are not wrapped.

From the README:

let users = Table("users")
let id = Expression<Int64>("id")
let name = Expression<String?>("name")
let email = Expression<String>("email")

try db.run(users.create { t in
    t.column(id, primaryKey: true)
    t.column(name)
    t.column(email, unique: true)
})
// CREATE TABLE "users" (
//     "id" INTEGER PRIMARY KEY NOT NULL,
//     "name" TEXT,
//     "email" TEXT NOT NULL UNIQUE
// )

let insert = users.insert(name <- "Alice", email <- "alice@mac.com")
let rowid = try db.run(insert)
// INSERT INTO "users" ("name", "email") VALUES ('Alice', 'alice@mac.com')

for user in db.prepare(users) {
    println("id: \(user[id]), name: \(user[name]), email: \(user[email])")
    // id: 1, name: Optional("Alice"), email: alice@mac.com
}

Note that both id and email, which are non-optional, are returned as such.

Sorry, this doesn't answer really answer my question. I don't really want type-safe, I want to be able to plug in my SQL directly. I'm fine with all answers output as strings, which is the default for SQLite. — Mark80, Nov 10 '15 at 23:08
@Mark80 Because SQLite values are dynamically returned at runtime, there's no way for the non-typesafe version to know what an array of values is going to be, other than optional. You can use Swift's numerous optional-unwrapping techniques, however, to deal with the issue! — stephencelis, Nov 11 '15 at 18:43

SQLite Swift db.prepare Optional() in statement values

3 Answers3