SwiftSQLite

SQLite wrapper for swift, nothing more, nothing less.

What is it?

A simple straight forward wrapper for the C API of SQLite.
Connect to SQLite databases, run queries, prepare statements and bind parameters, just like you'd do with the regular SQLite API, but in swift.
If you need a light local database API without all the bells and whistles - this library is for you.

What it is NOT

This is not another ORM database
It will not guess your scheme, create it, maintain it, and automagically sync to a remote server with zero code on your part - if you like the idea of zero coding - you're in the wrong line of work

Cook book

Create a DB connection

// For example, place the database in the user's library folder
guard let path = FileManager.default.urls(for: .libraryDirectory, in: .userDomainMask).first?.appendingPathComponent("db.sqlite").absoluteString else { fatalError("Could not create path") }
let db = try Database(path:path)

Open or close a DB connection explicitly

Sometimes you'd want to close or open a databasse explicitly, and not just using the CTOR and DTOR.

db.close() // will silently do nothing if already closed
try db.open(pathToFile) // Open a new connection, the old handle is closed first

Run a simple SQL statement

try db.exec("CREATE TABLE demo(a INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, b INTEGER NOT NULL)")

Prepare a statement and run with parameters

// Prepare once
let insert = try db.statement(sql: "INSERT INTO demo (b) VALUES (?)")
for i in 0..<10 {
    // Parameters are 1 based, this is how SQLite works
    try insert.bind(param: 1,i)
    try insert.step() // Run the statement
    let last_row_id = db.lastInsertRowId
    print("Last row id is: \(last_row_id)")
    try insert.reset() // must reset before we can run it again
    try insert.clearBindings() // Bindings are not cleared automatically, since we bind the same param again, this is not strictly required in this example, but it's good practice to clear the bindings.
}

Run SELECT queries

let select = try db.statement(sql: "SELECT a,b FROM demo WHERE b > ?")
try select.bind(param: 1, 5)
while try select.step() {
    guard let a = select.integer(column: 0), let b = select.string(column: 1) else {
        fatalError("Expected b to be non nil")
    }
    print("a: \(a), b: \(b)")
}

Additional helpers and wrappers

Use codables

struct Student : Codable {
    let name:String
    let grade:Int
    let city:String
}

db.useJSON1 = true
try db.exec("CREATE TABLE students (value json)") // JSON1 extension, JSON is actually TEXT
let ins = try db.statement(sql: "INSERT INTO students (value) VALUES (?)")
let student = Student(name:"Bart Simpson",grade:4,city:"Springfield")
try ins.bind(param: 1,student) // Bind a decodable object
try ins.step() // Execute the statement
let sel = try db.statement(sql: "SELECT json_extract(value,"$.name") FROM students")
guard try sel.step() else { fatalError("Expected step to succeed") }
guard let the_student:Student? = sel.object(column: 0) // deduce that the object is C by the return type, which must be an optional Decodable
else { fatalError("Expected object to be decoded to a C instance") }

Set journal mode

try db.set(journalMode: .wal) // Set journaling mode to WAL, useful when several processes read the database file, such as with an app and an app extension
let current_mode = try db.journalMode()

Auto vacuum

let db.set(autoVacuum:.incremental)
// do some inserts, deletes here
try db.incrementalVacuum()

Vacuum

try db.vacuum()

Foreign keys on/off

db.foreignKeys = true
// foreign keys are now enforced
try db.withoutForeignKeys {
    // This code will run without foreign keys enforcement 
}
try db.withForeignKeys {
    // This code will run with foreign keys enforcement
}

Recursive triggers on/off

Recursive triggers are off by default, but according to the docs, may be turned on by default in future versions.
An example of a self limiting recursive trigger:

CREATE TABLE rt(a INTEGER);
CREATE TRIGGER rt_trigger AFTER INSERT ON rt WHEN new.a < 10
BEGIN
    INSERT INTO rt VALUES (new.a + 1);
END;

db.recursiveTriggers = true
try db.exec("INSERT INTO rt VALUES (1)")
// rt should now have the 10 values (1..10)
// if recursiveTriggers was off - rt would only have 2 rows (1,2) as the trigger would not trigger itself.

Set busy timeout

try db.set(busyTimoeut:30)

This will install a busy handler that will sleep until the database unlocks or until the timeout expires, useful for WAL mode.
See busy handler and PRAGMA busy_timouet.
Note that there can be only a single busy handler for a database connection.

Versions

Set the user version or get the user, data or schema versions.
See PRAGMA data_version
See PRAGMA schema_version
See PRAGMA user_version

let user_version = try db.get(version: .user) // 0 by default
let schema_version = try db.get(version: .schema) 
let data_version = try db.get(version: .data) 
try db.set(version:12)

Custom functions

SQLite lets you create user defined functions, and SwiftSQLite lets you do that in swift 🤓.
We'll be using the Value and Result classes here.
A Value is an argument provided to your functions, and a Result, is a result from your functions.

Here's an example of a scalar function:

try db.createScalarFunction(name: "custom_sum_all_args", nArgs: 1, function: { (values:[Value]?) in
    var sum = 0
        values?.forEach({ value in
            sum += value.intValue
        })
    return Result(sum)
})

Now you can call:

SELECT custom_sum_all_args(1,2,3)

The returned value would be 6! (1+2+3).

Aggregate functions are a bit more complex, but not too much.
Here's a similar example, but as an aggregate function:

try db.createAggregateFunction(name: "custom_agg_test", step: { (values:[Value]?,result:Result) in
    // Sum all arguments
    var sum = 0
    values?.forEach({ v in
        sum += v.intValue
    })
    // Is it the first value we're setting?
    if result.resultType == .Null {
        // Set the initial value, result type will be automatically set to Int
        result.intValue = sum
    } else {
        // Nope, not the first time, sum with previous value
        result.intValue! += sum
    }
})

You can now use it as an aggrageted function:

SELECT custom_agg_test(value,1) FROM json_each(json_array(1,2,3))

The resulting value should be 9. ( (1 + 1) + (2 + 1) + (3 + 1) )

Logging

It is possible to install a logger by implementing the protocol Log:

/// Log protocol
public protocol Log  {
    /// Log SQL
    /// - parameters:
    ///   - prepare: SQL statement being prepared
    func log(prepare:String)
    /// Log error
    /// - parameters:
    ///  - error: Error text
    ///  - code: Error code (SQLite state)
    func log(error:String,code:Int)
    /// Log statement execution
    /// - parameters:
    ///  - sql: Executed SQL
    func log(sql:String)
    /// Log a message
    /// - parameters:
    ///   - message: Message to log (open DB, etc.)
    func log(message:String)
}

Set the static property logger for the Database class and you're ready to go.
A built in console logger is available, to use it, just add:
Database.logger = ConsoleLog()
Better set it up before using the library (but can be set in any point).

Install

Swift Package Manager

Add the following to your Package.swift dependencies:

dependencies: [
...
.package(url: "https://github.com/moshegottlieb/SwiftSQLite.git", from: "1.0.52")
...
]

How to add to an existing Xcode project

Select your project, in the general tab, under Frameworks and Libraries, hit the + button.
Enter the URL:
https://github.com/moshegottlieb/SwiftSQLite.git
Choose your version, and you're done.

Linux dependencies

The swift package manager does not automatically install the required dependencies.
On ubuntu/debian flavors:
sudo apt-get install libsqlite3-dev
On RedHat/Centos flavors:
sudo yum install sqlite-devel

moshegottlieb / swiftsqlite Goto Github PK

swiftsqlite's Introduction

SwiftSQLite

What is it?

What it is NOT

Cook book

Create a DB connection

Open or close a DB connection explicitly

Run a simple SQL statement

Prepare a statement and run with parameters

Run SELECT queries

Additional helpers and wrappers

Use codables

Set journal mode

Set busy timeout

Versions

Custom functions

Logging

Install

Swift Package Manager

How to add to an existing Xcode project

Linux dependencies

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