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https://github.com/nerdyc/Squeal

A Swift wrapper for SQLite databases
https://github.com/nerdyc/Squeal

database sql sqlite sqlite-database sqlite3 swift

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A Swift wrapper for SQLite databases

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# Squeal, a Swift interface to SQLite



Squeal provides access to [SQLite](http://www.sqlite.org/) databases in Swift. Its goal is to provide a

simple and straight-forward base API, allowing developers to build on top in ways that make sense for their apps. The

API provides direct SQL access, as well as a complete set of helpers to reduce SQL drudgery. It's not a goal of this

project to hide SQL from the developer, or to provide a generic object-mapping on top of SQLite.



### Features



* Small, straightforward Swift interface for accessing SQLite databases via SQL.

* Helper methods for most common types of SQL statements.

* Easy database schema versioning and migration DSL.

* Simple DatabasePool implementation for concurrent access to a database.



## Basic Usage



```swift

import Squeal



let db = Database()



// Create:

try db.createTable("contacts", definitions: [

    "id INTEGER PRIMARY KEY",

    "name TEXT",

    "email TEXT NOT NULL"

])



// Insert:

let contactId = try db.insertInto(

    "contacts",

    values: [

        "name": "Amelia Grey",

        "email": "[email protected]"

    ]

)



// Select:

struct Contact {

    let id:Int

    let name:String?

    let email:String

    

    init(row:Statement) throws {

        id = row.intValue("id") ?? 0

        name = row.stringValue("name")

        email = row.stringValue("email") ?? ""

    }

}



let contacts:[Contact] = try db.selectFrom(

    "contacts",

    whereExpr:"name IS NOT NULL",

    block: Contact.init

)



// Count:

let numberOfContacts = try db.countFrom("contacts")

```



The above example can be found in `Squeal.playground` to allow further exploration of Squeal's interface.



## Migrations



Any non-trivial app will need to change its database schema as features are added or updated. Unfortunately, SQLite

provides only minimal support for updating a database's schema. Things like removing a column or removing a `NON NULL`

require the entire database to be re-created with the new schema.



Squeal makes migrations easy by including a `Schema` class with a simple DSL for declaring your database migrations.

Once defined, the Schema can be used to migrate your database to the latest version.



Here's an example:



```swift

import Squeal



// Define a Schema:

let AppSchema = Schema(identifier:"contacts") { schema in

    // Version 1:

    schema.version(1) { v1 in

        // Create a Table:

        v1.createTable("contacts") { contacts in

            contacts.primaryKey("id")

            contacts.column("name", type:.Text)

            contacts.column("email", type:.Text, constraints:["NOT NULL"])

        }



        // Add an index

        v1.createIndex(

            "contacts_email",

            on: "contacts",

            columns: [ "email" ]

        )

    }

    

    // Version 2:

    schema.version(2) { v2 in        

        // Arbitrary SQL:

        v2.execute { db in

            try db.deleteFrom("contacts", whereExpr: "name IS NULL")

        }        

        // Tables can be altered in many ways.

        v2.alterTable("contacts") { contacts in

            contacts.alterColumn(

                "name",

                setConstraints: [ "NOT NULL" ]

            )

            contacts.addColumn("url", type: .Text)            

        }

    }

}



let db = Database()



// Migrate to the latest version:

let didMigrate = try AppSchema.migrate(db)



// Get the database version:

let migratedVersion = try db.queryUserVersionNumber()



// Reset the database:

try AppSchema.migrate(db, toVersion: 0)

```



The above example can be found in `Migrations.playground`.



## Installation



Squeal can be installed via [Carthage](https://github.com/Carthage/Carthage) or [CocoaPods](https://cocoapods.org).



### Carthage



To install using Carthage, simply add the following line to your `Cartfile`:



    github "nerdyc/Squeal"



### CocoaPods



To install using Carthage, simply add the following to the appropriate target in your `Podfile`:



    pod "Squeal"



## License



Squeal is released under the MIT License. Details are in the `LICENSE.txt` file in the project.



## Contributing



Contributions and suggestions are very welcome! No contribution is too small. Squeal (like Swift) is still evolving and feedback from the community is appreciated. Open an Issue, or submit a pull request!



The main requirement is for new code to be tested. Nobody appreciates bugs in their database.