Swift DSL for writing SQL statements.
let expressionId: Int = 123
let languageCode: LanguageCode? = .en
let regionCode: RegionCode? = .us
let statement = SQLiteStatement(
.SELECT(
.column(Translation["id"]!),
.column(Translation["expression_id"]!),
.column(Translation["language_code"]!),
.column(Translation["region_code"]!),
.column(Translation["value"]!)
),
.FROM_TABLE(Translation.self),
.WHERE(
.AND(
.comparison(Translation.expressionID, .equal(expressionID)),
.unwrap(languageCode, transform: { .comparison(Translation["language_code"]!, .equal($0.rawValue)) }),
.unwrap(regionCode, transform: { .comparison(Translation["region_code"]!, .equal($0.rawValue)) }),
.if(languageCode != nil && regionCode == nil, .logical(Translation.region, .isNull))
)
)
)The first part of the statement is rather clear:
SELECT translation.id, translation.expression_id, translation.language_code, translation.region_code, translation.value
FROM translation
...But take a closer look at the elements provided in the .AND block. The languageCode & regionCode are both optionals, and there is an
additional logical element clause when one is nil. With all of the optionals and logic, there is a possibility of producing 4 separate where
clauses.
WHERE translation.expression_id = 123
---
WHERE translation.expression_id = 123 AND translation.language_code = 'en' AND translation.region_code IS NULL
---
WHERE translation.expression_id = 123 AND translation.region_code = 'US'
---
WHERE translation.expression_id = 123 AND translation.language_code = 'en' AND translation.region_code = 'US'struct Translation: Entity, Identifiable {
let tableName: String = "translation"
/// Unique/Primary Key
@Field("id", unique: true, primaryKey: true, autoIncrement: true)
var id: Int = 0
/// Expression (Foreign Key)
@Field("expression_id", foreignKey: .init("expression", "id"))
var expressionID: Expression.ID = 0
/// Language of the translation
@Field("language_code")
var language: String = LanguageCode.default.rawValue
/// Region code specifier
@Field("region_code")
var region: String? = nil
/// The translated string
@Field("value")
var value: String = ""
}Using the Swift reflection api Mirror, the @Field property's are automatically synthesized.
extension Entity {
var attributes: [Attribute] {
var _columns: [Attribute] = []
let mirror = Mirror(reflecting: self)
for child in mirror.children {
if let column = child.value as? AttributeConvertible {
_columns.append(column.attribute)
} else if let column = child.value as? Attribute {
_columns.append(column)
}
}
return _columns
}
}Statement is distributed using the Swift Package Manager.
To install it into a project, add it as a dependency within your Package.swift manifest:
let package = Package(
...
dependencies: [
.package(url: "https://github.com/richardpiazza/Statement.git", .upToNextMinor(from: "0.7.2")
],
...
)Then import the Statement packages wherever you'd like to use it:
import Statement