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merged 4 commits into from
Sep 12, 2024
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docs(idempotency): add callout about undefined early return #3055

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5a4571e
docs(idempotency): add callout about undefined early return
dreamorosi Sep 12, 2024
3496aee
Update docs/utilities/idempotency.md
dreamorosi Sep 12, 2024
28bfd12
chore: accept suggestion
dreamorosi Sep 12, 2024
24df6dc
Merge branch 'main' into docs/idempotency_early-return
dreamorosi Sep 12, 2024
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2 changes: 2 additions & 0 deletions docs/utilities/idempotency.md
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Expand Up @@ -206,6 +206,8 @@ Similar to the `makeIdempotent` function wrapper, you can quickly make your Lamb
--8<-- "examples/snippets/idempotency/types.ts:3:16"
```

For the middleware to work, your Lambda function handler must return a value different from `undefined`. This is a [known limitation of the early return feature in Middy.js](https://github.com/middyjs/middy/issues/1236). If your use case requires early returns, you can use the `makeIdempotent` function wrapper instead.

### Choosing a payload subset for idempotency

Use [`IdempotencyConfig`](#customizing-the-default-behavior) to instruct the idempotent decorator to only use a portion of your payload to verify whether a request is idempotent, and therefore it should not be retried. When dealing with a more elaborate payload, where parts of the payload always change, you should use the **`eventKeyJmesPath`** parameter.
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21 changes: 13 additions & 8 deletions packages/idempotency/src/middleware/makeHandlerIdempotent.ts
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@@ -1,18 +1,18 @@
import { IdempotencyHandler } from '../IdempotencyHandler.js';
import { IdempotencyConfig } from '../IdempotencyConfig.js';
import {
cleanupMiddlewares,
IDEMPOTENCY_KEY,
cleanupMiddlewares,
} from '@aws-lambda-powertools/commons';
import type {
AnyFunction,
IdempotencyLambdaHandlerOptions,
} from '../types/IdempotencyOptions.js';
import type {
JSONValue,
MiddlewareLikeObj,
MiddyLikeRequest,
JSONValue,
} from '@aws-lambda-powertools/commons/types';
import { IdempotencyConfig } from '../IdempotencyConfig.js';
import { IdempotencyHandler } from '../IdempotencyHandler.js';
import type {
AnyFunction,
IdempotencyLambdaHandlerOptions,
} from '../types/IdempotencyOptions.js';

/**
* @internal
Expand Down Expand Up @@ -90,6 +90,11 @@ const shouldSkipIdempotency = (request: MiddyLikeRequest): boolean => {
* ).use(makeHandlerIdempotent({ persistenceStore: dynamoDBPersistenceLayer }));
* ```
*
* For the middleware to work, your Lambda function handler must return a value different from `undefined`.
* This is a [known limitation of the early return feature in Middy.js](https://github.com/middyjs/middy/issues/1236).
*
* If your use case requires early returns, you can use the {@link index.makeIdempotent | makeIdempotent()} function wrapper instead.
*
* @param options - Options for the idempotency middleware
*/
const makeHandlerIdempotent = (
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