Transactions

Database transactions allow your application to make a series of database changes in an all-or-nothing commit. Consider an HTTP request that creates a new Order and has an afterChange hook to update the stock count of related Items. If an error occurs when updating an Item and an HTTP error is returned to the user, you would not want the new Order to be persisted or any other items to be changed either. This kind of interaction with the database is handled seamlessly with transactions.

By default, Payload will use transactions for all operations, as long as it is supported by the configured database. Database changes are contained within all Payload operations and any errors thrown will result in all changes being rolled back without being committed. When transactions are not supported by the database, Payload will continue to operate as expected without them.

The initial request made to Payload will begin a new transaction and attach it to the req.transactionID. If you have a hook that interacts with the database, you can opt-in to using the same transaction by passing the req in the arguments. For example:

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const afterChange: CollectionAfterChangeHook = async ({ req }) => {
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// because req.transactionID is assigned from Payload and passed through,
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// my-slug will only persist if the entire request is successful
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await req.payload.create({
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req,
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collection: 'my-slug',
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data: {
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some: 'data',
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},
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})
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}

Async Hooks with Transactions

Since Payload hooks can be async and be written to not await the result, it is possible to have an incorrect success response returned on a request that is rolled back. If you have a hook where you do not await the result, then you should not pass the req.transactionID.

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const afterChange: CollectionAfterChangeHook = async ({ req }) => {
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// WARNING: an async call made with the same req, but NOT awaited,
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// may fail resulting in an OK response being returned with response data that is not committed
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const dangerouslyIgnoreAsync = req.payload.create({
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req,
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collection: 'my-slug',
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data: {
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some: 'other data',
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},
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})
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// Should this call fail, it will not rollback other changes
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// because the req (and its transactionID) is not passed through
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const safelyIgnoredAsync = req.payload.create({
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collection: 'my-slug',
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data: {
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some: 'other data',
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},
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})
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}

Direct Transaction Access

When writing your own scripts or custom endpoints, you may wish to have direct control over transactions. This is useful for interacting with your database outside of Payload's local API.

The following functions can be used for managing transactions:

payload.db.beginTransaction - Starts a new session and returns a transaction ID for use in other Payload Local API calls. payload.db.commitTransaction - Takes the identifier for the transaction, finalizes any changes. payload.db.rollbackTransaction - Takes the identifier for the transaction, discards any changes.

Next

MongoDB