How to Use IdempotencyKeyService

In this document, you'll learn how to use the IdempotencyKeyServiceCopy to Clipboard.

Overview

You can use the IdempotencyKeyServiceCopy to Clipboard within your custom development to ensure that your custom endpoints and operations can be safely retried or continued if an error occurs. This guide is also useful if you're overriding an existing feature in Medusa that uses the IdempotencyKeyServiceCopy to Clipboard and you want to maintain its usage, such as if you're overriding the cart completion strategy.

The IdempotencyKeyServiceCopy to Clipboard includes methods that can be used to create and update idempotency keys, among other functionalities.

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Create Idempotency Key

You can create an idempotency key within an endpoint using the createCopy to Clipboard method of the IdempotencyKeyServiceCopy to Clipboard:

router.post("/custom-route", async (req, res) => {
  // ...
  const idempotencyKey = await idempotencyKeyService.create({
    request_method: req.method,
    request_params: req.params,
    request_path: req.path,
  })
  // ...
})

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The method requires as a parameter an object having the following properties:

• request_methodCopy to Clipboard: a string indicating the request method to be associated with the idempotency key.
• request_paramsCopy to Clipboard: an object indicating the request parameters to be associated with the idempotency key.
• request_pathCopy to Clipboard: a string indicating the request path to be associated with the idempotency key.

The method handles generating the idempotency key value and saving the idempotency key with its details in the database. It returns the full idempotency key object.

Alternatively, you can use the initializeRequestCopy to Clipboard method that allows you to retrieve an idempotency key based on the value passed in the Idempotency-KeyCopy to Clipboard header of the request if it exists, or create a new key otherwise. For example:

router.post("/custom-route", async (req, res) => {
  // ...
  const headerKey = req.get("Idempotency-Key") || ""

  const idempotencyKey = await idempotencyKeyService
    .initializeRequest(
      headerKey,
      req.method,
      req.params,
      req.path
    )
  // ...
})

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The method requires the following parameters:

1. The first parameter is the key existing in the header of the request, if there's any.
2. The second parameter is the request's method.
3. The third parameter is the request's parameters.
4. The fourth method is the request's path.

The method returns the full idempotency key object.

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Perform Actions Within Idempotency Key Stages

Each idempotency key stage typically has transactions performed within it. Using the IdempotencyKeyServiceCopy to Clipboard's workStageCopy to Clipboard method allows you to perform related functionalities in transactional isolation within each stage. You can access the stage or recovery point of an idempotency key using the recovery_pointCopy to Clipboard attribute.

The following example is taken from the CartCompletionStrategyCopy to Clipboard implemented in the Medusa backend:

class CartCompletionStrategy
  extends AbstractCartCompletionStrategy {
  // ...

  async complete(
    id: string,
    ikey: IdempotencyKey,
    context: RequestContext
  ): Promise<CartCompletionResponse> {
    // ...
    let inProgress = true
    let err: unknown = false

    while (inProgress) {
      switch (idempotencyKey.recovery_point) {
        case "started": {
          await this.activeManager_
            .transaction(
              "SERIALIZABLE", 
              async (transactionManager) => {
                idempotencyKey = 
                  await this.idempotencyKeyService_
                    .withTransaction(transactionManager)
                    .workStage(
                      idempotencyKey.idempotency_key,
                      async (manager) =>
                        await this.handleCreateTaxLines(
                          id, 
                          {
                            manager,
                          }
                        )
                    )
              }
            )
            .catch((e) => {
              inProgress = false
              err = e
            })
          break
        }

        case "tax_lines_created": {
          // ...
        }

        case "payment_authorized": {
          // ...
        }

        case "finished": {
          // ...
        }

        default: {
          // ...
        }
      }
    }

    // ...
  }
}

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The method requires the following parameters:

1. The first parameter is the idempotency key value.
2. The second parameter is a callback function to be executed. The function should return an object that is used to update the idempotency key's details. The object can include the following parameters:
   1. recovery_pointCopy to Clipboard: a string indicating the new recovery point associated with the idempotency key's operation. If no recovery_pointCopy to Clipboard is returned in the object, the finishedCopy to Clipboard recovery point is assigned by default.
   2. response_codeCopy to Clipboard: a number indicating the latest response code of the idempotency key's operation.
   3. response_bodyCopy to Clipboard: an object indicating the latest response body of the idempotency key's operation.

The method returns an updated idempotency key object.