Persisted GraphQL queries

Persisted queries are GraphQL queries that are created and stored on the Adobe Experience Manager (AEM) as a Cloud Service server. They can be requested with a GET request by client applications. The response of a GET request can be cached at the dispatcher and CDN layers, ultimately improving the performance of the requesting client application. This differs from standard GraphQL queries, which are executed using POST requests where the response cannot easily be cached.

The GraphiQL IDE is available in AEM for you to develop, test, and persist your GraphQL queries, before transferring to your production environment. For cases that need customization (for example, when customizing the cache) you can use the API; see the cURL example provided in How to persist a GraphQL query.

Persisted Queries and Endpoints

Persisted queries must always use the endpoint related to the appropriate Sites configuration; so they can use either, or both:

• The Global configuration and endpoint
  The query has access to all Content Fragment Models.
• Specific Sites configuration(s) and endpoint(s)
  Creating a persisted query for a specific Sites configuration requires a corresponding Sites-configuration-specific endpoint (to provide access to the related Content Fragment Models).
  For example, to create a persisted query specifically for the WKND Sites configuration, a corresponding WKND-specific Sites configuration, and a WKND-specific endpoint must be created in advance.

For example, if there is a particular query called my-query, which uses a model my-model from the Sites configuration my-conf:

• You can create a query using the my-conf specific endpoint, and then the query is saved as following:
  /conf/my-conf/settings/graphql/persistentQueries/my-query
• You can create the same query using global endpoint, but then the query is saved as following:
  /conf/global/settings/graphql/persistentQueries/my-query

How to persist a GraphQL query

It is recommended to persist queries on an AEM author environment initially and then transfer the query to your production AEM publish environment, for use by applications.

There are various methods of persisting queries, including:

• GraphiQL IDE - see Saving Persisted Queries (preferred method)
• cURL - see the following example
• Other tools, including Postman

The GraphiQL IDE is the preferred method for persisting queries. To persist a given query using the cURL command line tool:

1. Prepare the query by PUTing it to the new endpoint URL /graphql/persist.json/<config>/<persisted-label>.

   For example, create a persisted query:

   $ curl -X PUT \
       -H 'authorization: Basic YWRtaW46YWRtaW4=' \
       -H "Content-Type: application/json" \
       "http://localhost:4502/graphql/persist.json/wknd/plain-article-query" \
       -d \
   '{
     articleList {
       items{
           _path
           author
           main {
               json
           }
       }
     }
   }'
   

2. At this point, check the response.

   For example, check for success:

   {
     "action": "create",
     "configurationName": "wknd",
     "name": "plain-article-query",
     "shortPath": "/wknd/plain-article-query",
     "path": "/conf/wknd/settings/graphql/persistentQueries/plain-article-query"
   }
   

3. You can then request the persisted query by GETing the URL /graphql/execute.json/<shortPath>.

   For example, use the persisted query:

   $ curl -X GET \
       http://localhost:4502/graphql/execute.json/wknd/plain-article-query
   

4. Update a persisted query by POSTing to an already existing query path.

   For example, use the persisted query:

   $ curl -X POST \
       -H 'authorization: Basic YWRtaW46YWRtaW4=' \
       -H "Content-Type: application/json" \
       "http://localhost:4502/graphql/persist.json/wknd/plain-article-query" \
       -d \
   '{
     articleList {
       items{
           _path
           author
           main {
               json
           }
         referencearticle {
           _path
         }
       }
     }
   }'
   

5. Create a wrapped plain query.

   For example:

   $ curl -X PUT \
       -H 'authorization: Basic YWRtaW46YWRtaW4=' \
       -H "Content-Type: application/json" \
       "http://localhost:4502/graphql/persist.json/wknd/plain-article-query-wrapped" \
       -d \
   '{ "query": "{articleList { items { _path author main { json } referencearticle { _path } } } }"}'
   

6. Create a wrapped plain query with cache control.

   For example:

   $ curl -X PUT \
       -H 'authorization: Basic YWRtaW46YWRtaW4=' \
       -H "Content-Type: application/json" \
       "http://localhost:4502/graphql/persist.json/wknd/plain-article-query-max-age" \
       -d \
   '{ "query": "{articleList { items { _path author main { json } referencearticle { _path } } } }", "cache-control": { "max-age": 300 }}'
   

7. Create a persisted query with parameters:

   For example:

   $ curl -X PUT \
       -H 'authorization: Basic YWRtaW46YWRtaW4=' \
       -H "Content-Type: application/json" \
       "http://localhost:4502/graphql/persist.json/wknd/plain-article-query-parameters" \
       -d \
   'query GetAsGraphqlModelTestByPath($apath: String!, $withReference: Boolean = true) {
     articleByPath(_path: $apath) {
       item {
         _path
           author
           main {
           plaintext
           }
           referencearticle @include(if: $withReference) {
           _path
           }
         }
       }
     }'
   

How to execute a Persisted query

To execute a Persisted query, a client application makes a GET request using the following syntax:

GET <AEM_HOST>/graphql/execute.json/<PERSISTENT_PATH>

Where PERSISTENT_PATH is a shortened path to where the Persisted query is saved.

1. For example, wknd is the configuration name and plain-article-query is the name of the Persisted query. To execute the query:

   $ curl -X GET \
       https://publish-p123-e456.adobeaemcloud.com/graphql/execute.json/wknd/plain-article-query
   

2. Executing a query with parameters.

   NOTE

   Query variables and values must be properly encoded when executing a Persisted query.

   For example:

   $ curl -X GET \
       "https://publish-p123-e456.adobeaemcloud.com/graphql/execute.json/wknd/plain-article-query-parameters%3Bapath%3D%2Fcontent%2Fdam%2Fwknd%2Fen%2Fmagazine%2Falaska-adventure%2Falaskan-adventures%3BwithReference%3Dfalse
   

   See using query variables for more details.

Using query variables

Query variables can be used with Persisted Queries. The query variables are appended to the request prefixed with a semicolon (;) using the variable name and value. Multiple variables are separated by semicolons.

The pattern looks like the following:

<AEM_HOST>/graphql/execute.json/<PERSISTENT_QUERY_PATH>;variable1=value1;variable2=value2

For example, the following query contains a variable activity to filter a list based on an activity value:

query getAdventuresByActivity($activity: String!) {
      adventureList (filter: {
        adventureActivity: {
          _expressions: [
            {
              value: $activity
            }
          ]
        }
      }){
        items {
          _path
        adventureTitle
        adventurePrice
        adventureTripLength
      }
    }
  }

This query can be persisted under a path wknd/adventures-by-activity. To call the Persisted query where activity=Camping the request would look like this:

<AEM_HOST>/graphql/execute.json/wknd/adventures-by-activity%3Bactivity%3DCamping

The UTF-8 encoding %3B is for ; and %3D is the encoding for =. The query variables and any special characters must be encoded properly for the Persisted query to execute.

Caching your persisted queries

Persisted queries are recommended as they can be cached at the Dispatcher and Content Delivery Network (CDN) layers, ultimately improving the performance of the requesting client application.

By default AEM will invalidate cache based on a Time To Live (TTL) definition. These TTLs can be defined by the following parameters. These parameters can be accessed by various means, with variations in the names according to the mechanism used:

Author instances

For author instances the default values are:

• max-age : 60
• s-maxage : 60
• stale-while-revalidate : 86400
• stale-if-error : 86400

These:

• cannot be overwritten:
  • with an OSGi configuration
• can be overwritten:
  • by a request that defines HTTP header settings using cURL; it should include suitable settings for cache-control and/or surrogate-control; for examples, see Managing Cache at the Persisted Query Level
  • if you specify values in the Headers dialog of the GraphiQL IDE

Publish instances

For publish instances the default values are:

• max-age : 60
• s-maxage : 7200
• stale-while-revalidate : 86400
• stale-if-error : 86400

These can be overwritten:

• from the GraphQL IDE

• at the Persisted Query Level; this involves posting the query to AEM using cURL in your command line interface, and publishing the Persisted Query.

• with Cloud Manager variables

• with an OSGi configuration

Managing HTTP Cache Headers in the GraphiQL IDE

The GraphiQL IDE - see Saving Persisted Queries

Managing Cache at the Persisted Query Level

This involves posting the query to AEM using cURL in your command line interface.

For an example of the PUT (create) method:

curl -u admin:admin -X PUT \
--url "http://localhost:4502/graphql/persist.json/wknd/plain-article-query-max-age" \
--header "Content-Type: application/json" \
--data '{ "query": "{articleList { items { _path author } } }", "cache-control": { "max-age": 300 }, "surrogate-control": {"max-age":600, "stale-while-revalidate":1000, "stale-if-error":1000} }'

For an example of the POST (update) method:

curl -u admin:admin -X POST \
--url "http://localhost:4502/graphql/persist.json/wknd/plain-article-query-max-age" \
--header "Content-Type: application/json" \
--data '{ "query": "{articleList { items { _path author } } }", "cache-control": { "max-age": 300 }, "surrogate-control": {"max-age":600, "stale-while-revalidate":1000, "stale-if-error":1000} }'

The cache-control can be set at the creation time (PUT) or later on (for example, via a POST request for instance). The cache-control is optional when creating the persisted query, as AEM can provide the default value. See How to persist a GraphQL query, for an example of persisting a query using cURL.

Managing Cache with Cloud Manager variables

Cloud Manager Environment Variables can be defined with Cloud Manager to define the required values:

Managing Cache with an OSGi configuration

To manage the cache globally, you can configure the OSGi settings for the Persisted Query Service Configuration.

The default OSGi configuration for publish instances:

• reads the Cloud Manager variables if available:

  OSGi Configuration Property	reads this	Cloud Manager Variable
  cacheControlMaxAge	reads	graphqlCacheControl
  surrogateControlMaxAge	reads	graphqlSurrogateControl
  surrogateControlStaleWhileRevalidate	reads	graphqlStaleWhileRevalidate
  surrogateControlStaleIfError	reads	graphqlStaleIfError

• and if not available, the OSGi configuration uses the default values for publish instances.

Configuring the query response code

By default the PersistedQueryServlet sends a 200 response when it executes a query, regardless of the actual result.

You can configure the OSGi settings for the Persisted Query Service Configuration to control which status code is returned by the /execute.json/persisted-query endpoint, when there is an error in the persisted query.

The field Respond with application/graphql-response+json (responseContentTypeGraphQLResponseJson) can be defined as required:

• false (default value):
  It does not matter whether the persisted query is successful or not. The /execute.json/persisted-query returns the status code 200 and the Content-Type header returned is application/json.

• true:
  The endpoint will return 400 or 500 as appropriate when there is any form of error upon running the persisted query. Also, the returned Content-Type is application/graphql-response+json.

  NOTE

  See https://graphql.github.io/graphql-over-http/draft/#sec-Status-Codes

Encoding the query URL for use by an app

For use by an application, any special characters used when constructing query variables (that is, semicolons (;), equal sign (=), slashes /) must be converted to use the corresponding UTF-8 encoding.

For example:

curl -X GET \ "https://publish-p123-e456.adobeaemcloud.com/graphql/execute.json/wknd/adventure-by-path%3BadventurePath%3D%2Fcontent%2Fdam%2Fwknd%2Fen%2Fadventures%2Fbali-surf-camp%2Fbali-surf-camp"

The URL can be broken down into the following parts:

In plain text the request URI looks like the following:

/graphql/execute.json/wknd/adventure-by-path;adventurePath=/content/dam/wknd/en/adventures/bali-surf-camp/bali-surf-camp

To use a persisted query in a client app, the AEM headless client SDK should be used for JavaScript, Java, or NodeJS. The Headless Client SDK will automatically encode any query variables appropriately in the request.

Transferring a persisted query to your Production environment

Persisted queries should always be created on an AEM Author service and then published (replicated) to an AEM Publish service. Often, Persisted queries are created and tested on lower environments like local or Development environments. It is then necessary to promote Persisted queries to higher level environments, ultimately making them available on a production AEM Publish environment for client applications to consume.

Package Persisted queries

Persisted queries can be built into AEM Packages. AEM Packages can then be downloaded and installed on different environments. AEM Packages can also be replicated from an AEM Author environment to AEM Publish environments.

To create a Package:

1. Navigate to Tools > Deployment > Packages.
2. Create a new package by tapping Create Package. This opens a dialog to define the Package.
3. In the Package Definition Dialog, under General enter a Name like “wknd-persistent-queries”.
4. Enter a version number like “1.0”.
5. Under Filters add a new Filter. Use the Path Finder to select the persistentQueries folder beneath the configuration. For example, for the wknd configuration, the full path is /conf/wknd/settings/graphql/persistentQueries.
6. Select Save to save the new Package definition and close the dialog.
7. Select the Build button in the created Package definition.

After the package has been built you can:

• Download the package and re-upload on a different environment.
• Replicate the package by tapping More > Replicate. This will replicate the package to the connected AEM Publish environment.