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44 lines
1.5 KiB
44 lines
1.5 KiB
class Migrator {
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constructor (opts = {}) {
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const migrations = opts.migrations || []
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// sort migrations by version
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this.migrations = migrations.sort((a, b) => a.version - b.version)
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// grab migration with highest version
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const lastMigration = this.migrations.slice(-1)[0]
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// use specified defaultVersion or highest migration version
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this.defaultVersion = opts.defaultVersion || (lastMigration && lastMigration.version) || 0
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}
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// run all pending migrations on meta in place
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async migrateData (versionedData = this.generateInitialState()) {
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const pendingMigrations = this.migrations.filter(migrationIsPending)
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for (const index in pendingMigrations) {
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const migration = pendingMigrations[index]
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versionedData = await migration.migrate(versionedData)
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if (!versionedData.data) throw new Error('Migrator - migration returned empty data')
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if (versionedData.version !== undefined && versionedData.meta.version !== migration.version) throw new Error('Migrator - Migration did not update version number correctly')
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}
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return versionedData
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// migration is "pending" if it has a higher
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// version number than currentVersion
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function migrationIsPending (migration) {
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return migration.version > versionedData.meta.version
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}
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}
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generateInitialState (initState) {
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return {
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meta: {
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version: this.defaultVersion,
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},
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data: initState,
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}
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}
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}
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module.exports = Migrator
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