76 lines
3.1 KiB
Swift
76 lines
3.1 KiB
Swift
import Foundation
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import DataLiteCore
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/// Represents a database migration step associated with a specific version.
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///
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/// Each `Migration` contains a reference to a migration script file (usually a `.sql` file) and the
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/// version to which this script corresponds. The script is expected to be bundled with the application.
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///
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/// You can initialize a migration directly with a URL to the script, or load it from a resource
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/// embedded in a bundle.
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public struct Migration<Version: VersionRepresentable>: Hashable, Sendable {
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// MARK: - Properties
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/// The version associated with this migration step.
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public let version: Version
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/// The URL pointing to the migration script (e.g., an SQL file).
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public let scriptURL: URL
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/// The SQL script associated with this migration.
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///
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/// This computed property reads the contents of the file at `scriptURL` and returns it as a
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/// `SQLScript` instance. Use this to access and execute the migration's SQL commands.
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///
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/// - Throws: An error if the script file cannot be read or is invalid.
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public var script: SQLScript {
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get throws {
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try SQLScript(contentsOf: scriptURL)
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}
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}
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// MARK: - Inits
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/// Creates a migration with a specified version and script URL.
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///
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/// - Parameters:
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/// - version: The version this migration corresponds to.
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/// - scriptURL: The file URL to the migration script.
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public init(version: Version, scriptURL: URL) {
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self.version = version
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self.scriptURL = scriptURL
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}
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/// Creates a migration by locating a script resource in the specified bundle.
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///
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/// This initializer attempts to locate a script file in the provided bundle using the specified
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/// resource `name` and optional `extension`. The `name` parameter may include or omit the file extension.
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///
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/// - If `name` includes an extension (e.g., `"001_init.sql"`), pass `extension` as `nil` or an empty string.
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/// - If `name` omits the extension (e.g., `"001_init"`), specify the extension separately
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/// (e.g., `"sql"`), or leave it `nil` if the file has no extension.
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///
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/// - Important: Passing a name that already includes the extension while also specifying a non-`nil`
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/// `extension` may result in failure to locate the file.
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///
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/// - Parameters:
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/// - version: The version this migration corresponds to.
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/// - name: The resource name of the script file. May include or omit the file extension.
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/// - extension: The file extension, if separated from the name. Defaults to `nil`.
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/// - bundle: The bundle in which to search for the resource. Defaults to `.main`.
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///
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/// - Returns: A `Migration` if the resource file is found; otherwise, `nil`.
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public init?(
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version: Version,
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byResource name: String,
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extension: String? = nil,
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in bundle: Bundle = .main
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) {
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guard let url = bundle.url(
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forResource: name,
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withExtension: `extension`
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) else { return nil }
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self.init(version: version, scriptURL: url)
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}
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}
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