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cache-lookup-value-policy.md

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title Azure API Management policy reference - cache-lookup-value | Microsoft Docs
description Reference for the cache-lookup-value policy available for use in Azure API Management. Provides policy usage, settings, and examples.
services api-management
author dlepow
ms.service azure-api-management
ms.topic reference
ms.date 07/23/2024
ms.author danlep

Get value from cache

[!INCLUDE api-management-availability-all-tiers]

Use the cache-lookup-value policy to perform cache lookup by key and return a cached value. The key can have an arbitrary string value and is typically provided using a policy expression.

Note

This policy must have a corresponding Store value in cache policy.

[!INCLUDE api-management-cache-volatile]

[!INCLUDE api-management-policy-generic-alert]

Policy statement

<cache-lookup-value key="cache key value"
    default-value="value to use if cache lookup resulted in a miss"
    variable-name="name of a variable looked up value is assigned to"
    caching-type="prefer-external | external | internal" />

Attributes

Attribute Description Required Default
caching-type Choose between the following values of the attribute:
- internal to use the built-in API Management cache,
- external to use the external cache as described in Use an external Redis-compatible cache in Azure API Management,
- prefer-external to use external cache if configured or internal cache otherwise.

Policy expressions aren't allowed.		 No prefer-external
default-value A value that will be assigned to the variable if the cache key lookup resulted in a miss. If this attribute is not specified, null is assigned. Policy expressions are allowed. No null
key Cache key value to use in the lookup. Policy expressions are allowed. Yes N/A
variable-name Name of the context variable the looked up value will be assigned to, if lookup is successful. If lookup results in a miss, the variable will not be set. Policy expressions aren't allowed. Yes N/A

Usage

Usage notes

  • API Management only caches responses to HTTP GET requests.
  • This policy can only be used once in a policy section.
  • This policy is not supported inside a policy fragment.
  • [!INCLUDE api-management-cache-rate-limit]

Example

This example shows how to use the cache-lookup-value policy to retrieve a user profile from the cache. The key for the cache lookup is constructed using a policy expression that combines a string with the value of the enduserid context variable.

Note

[!INCLUDE api-management-cache-availability]

See a cache-store-value example to store the user profile in the cache.

<cache-lookup-value
    key="@("userprofile-" + context.Variables["enduserid"])"
    variable-name="userprofile" />
<rate-limit calls="10" renewal-period="60" />

For more information and examples of this policy, see Custom caching in Azure API Management.

Related policies

[!INCLUDE api-management-policy-ref-next-steps]