46 lines
1.4 KiB
TypeScript
46 lines
1.4 KiB
TypeScript
import { NonNegativeInteger } from "type-fest";
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import { MigrationHelper } from "./migration-helper";
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export const IRREVERSIBLE = new Error("Irreversible migration");
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export type VersionFrom<T> =
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T extends Migrator<infer TFrom, number>
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? TFrom extends NonNegativeInteger<TFrom>
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? TFrom
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: never
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: never;
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export type VersionTo<T> =
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T extends Migrator<number, infer TTo>
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? TTo extends NonNegativeInteger<TTo>
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? TTo
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: never
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: never;
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export type Direction = "up" | "down";
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export abstract class Migrator<TFrom extends number, TTo extends number> {
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constructor(
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public fromVersion: TFrom,
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public toVersion: TTo,
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) {
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if (fromVersion == null || toVersion == null) {
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throw new Error("Invalid migration");
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}
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if (fromVersion > toVersion) {
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throw new Error("Invalid migration");
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}
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}
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shouldMigrate(helper: MigrationHelper, direction: Direction): Promise<boolean> {
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const startVersion = direction === "up" ? this.fromVersion : this.toVersion;
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return Promise.resolve(helper.currentVersion === startVersion);
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}
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abstract migrate(helper: MigrationHelper): Promise<void>;
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abstract rollback(helper: MigrationHelper): Promise<void>;
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async updateVersion(helper: MigrationHelper, direction: Direction): Promise<void> {
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const endVersion = direction === "up" ? this.toVersion : this.fromVersion;
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helper.currentVersion = endVersion;
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await helper.set("stateVersion", endVersion);
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}
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}
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