HTTPPostCachingPolicy.xml

<!--    Custom caching policy for on HTTP POST for Azure API Management:
        1. Policy looks in the Request body - 'cacheKey' property which then used as cache key.           
            Expected values are: <null>, ALL or NOEXPIRED           
            Defaults to ALL in case <null>
        2. Cache expiration set to 60 seconds/1 minute    
!-->

<policies>
    <inbound>
        <base />
        <!-- CACHING: checks for cacheKey property in message body !-->
        <set-variable name="cacheKey" value="@(context.Request.Body?.As<JObject>(preserveContent: true)["cacheKey"]?.ToString() ?? "ALL")" />
        <cache-lookup-value key="@((string)context.Variables["cacheKey"])" variable-name="cachedResponseValue" />

        <choose>
            <when condition="@(context.Variables.ContainsKey("cachedResponseValue"))">
                <return-response>
                    <set-header name="Content-Type" exists-action="override">application/json</set-header>
                    <set-body>@((string)context.Variables["cachedResponseValue"])</set-body>
                </return-response>
            </when>
        </choose>
    </inbound>

    <backend>
        <base />
    </backend>
    
    <outbound>
        <base />
        <set-variable name="responseValue" value="@(context.Response.Body.As<string>(preserveContent: true))" />
        <cache-store-value key="@((string)context.Variables["cacheKey"])" value="@((string)context.Variables["responseValue"])" duration="60" />
    </outbound>
    
    <on-error>
        <base />
    </on-error>
</policies>