AEM GraphQL API for use with Content Fragments

Learn how to use Content Fragments in Adobe Experience Manager (AEM) with the AEM GraphQL API for headless content delivery.

AEM GraphQL API used with Content Fragments is heavily based on the standard, open-source GraphQL API.

Using the GraphQL API in AEM enables the efficient delivery of Content Fragments to JavaScript clients in headless CMS implementations:

• Avoiding iterative API requests as with REST,
• Ensuring that delivery is limited to the specific requirements,
• Allowing for bulk delivery of exactly what is needed for rendering as the response to a single API query.

Prerequisites

Customers using GraphQL should install the AEM Content Fragment with GraphQL Index Package 1.0.5. See the Release Notes for further details.

The GraphQL API

GraphQL is:

• “…a query language for APIs and a runtime for fulfilling those queries with your existing data. GraphQL provides a complete and understandable description of the data in your API. It gives clients the power to ask for exactly what they need and nothing more, makes it easier to evolve APIs over time, and enables powerful developer tools.”.

  See GraphQL.org

• “…an open spec for a flexible API layer. Put GraphQL over your existing backends so you can build products faster than ever before…”.

  See Explore GraphQL.

• “…a data query language and specification developed internally by Facebook in 2012 before being publicly open-sourced in 2015. It provides an alternative to REST-based architectures with the purpose of increasing developer productivity and minimizing amounts of data transferred. GraphQL is used in production by hundreds of organizations of all sizes…”

  See GraphQL Foundation.

For further information about the GraphQL API, see the following sections (among many other resources):

• At graphql.org:

  • Introduction to GraphQL

  • The GraphQL Specification

• At graphql.com:

  • Tutorials

The GraphQL for AEM implementation is based on the standard GraphQL Java™ Library. See:

• graphQL.org - Java

• GraphQL Java™ at GitHub

GraphQL Terminology

GraphQL uses the following:

• Queries

• Schemas and Types:

  • Schemas are generated by AEM based on the Content Fragment Models.
  • Using your schemas, GraphQL presents the types and operations allowed for the GraphQL for AEM implementation.

• Fields

• GraphQL Endpoint

  • The path in AEM that responds to GraphQL queries, and provides access to the GraphQL schemas.

  • See Enabling your GraphQL Endpoint for further details.

See the (GraphQL.org) Introduction to GraphQL for comprehensive details, including the Best Practices.

GraphQL Query Types

With GraphQL you can perform queries to return either:

• A single entry

• A list of entries

AEM provides capabilities to convert queries (both types) to Persisted Queries that are cached by Dispatcher and the CDN.

GraphQL Query Best Practices (Dispatcher and CDN)

The Persisted Queries are the recommended method to be used on publish instances as:

• they are cached
• they are managed centrally by AEM

GraphQL queries using POST requests are not recommended as they are not cached, so on a default instance the Dispatcher is configured to block such queries.

While GraphQL also supports GET requests, these requests can hit limits (for example the length of the URL) that can be avoided using Persisted Queries.

GraphiQL Interface

An implementation of the standard GraphiQL interface is available for use with AEM GraphQL.

This interface lets you directly input, and test, queries.

For example:

• http://localhost:4502/content/graphiql.html

It provides features such as syntax-highlighting, auto-complete, auto-suggest, together with a history and online documentation:

Use Cases for Author and Publish Environments

The use cases can depend on the type of AEM environment:

• Publish environment; used to:

  • Query data for JS application (standard use-case)

• Author environment; used to:

  • Query data for “content management purposes”:
    • GraphQL in AEM is a read-only API.
    • The REST API can be used for CR(u)D operations.

Permissions

The permissions are required for accessing Assets.

GraphQL queries are run with the permission of the AEM user of the underlying request. If the user does not have read access to some fragments (stored as Assets), they do not become part of the result set.

Also, the user must have access to a GraphQL endpoint to be able to run GraphQL queries.

Schema Generation

GraphQL is a typed API, which means that data must be clearly structured and organized by type.

The GraphQL specification provides a series of guidelines on how to create a robust API for interrogating data on a certain instance. To complete these guidelines, a client must fetch the Schema, which contains all the types necessary for a query.

For Content Fragments, the GraphQL schemas (structure and types) are based on Enabled Content Fragment Models and their data types.

For example, if a user created a Content Fragment Model called Article, then AEM generates a GraphQL type ArticleModel. The fields within this type correspond to the fields and data types defined in the model. In addition, it creates some entrypoints for the queries that operate on this type, such as articleByPath or articleList.

1. A Content Fragment Model:

   

2. The corresponding GraphQL schema (output from GraphiQL automatic documentation):
   

   This image shows that the generated type ArticleModel contains several fields.

   • Three of them have been controlled by the user: author, main, and referencearticle.

   • The other fields were added automatically by AEM, and represent helpful methods to provide information about a certain Content Fragment. In this example, (the helper fields) _path, _metadata, _variations.

3. After a user creates a Content Fragment based on the Article model, it can then be interrogated through GraphQL. For examples, see the Sample Queries (based on a sample Content Fragment structure for use with GraphQL).

In GraphQL for AEM, the schema is flexible. This flexibility means that it is auto-generated each time a Content Fragment Model is created, updated, or deleted. The data schema caches are also refreshed when you update a Content Fragment Model.

The Sites GraphQL service listens (in the background) for any modifications made to a Content Fragment Model. When updates are detected, only that part of the schema is regenerated. This optimization saves time and provides stability.

So for example, if you:

1. Install a package containing Content-Fragment-Model-1 and Content-Fragment-Model-2:

   1. GraphQL types for Model-1 and Model-2 are generated.

2. Then modify Content-Fragment-Model-2:

   1. Only the Model-2 GraphQL type gets updated.

   2. Whereas Model-1 remains the same.

The schema is served through the same endpoint as the GraphQL queries, with the client handling the fact that the schema is called with the extension GQLschema. For example, performing a simple GET request on /content/cq:graphql/global/endpoint.GQLschema results in the output of the schema with the Content-type: text/x-graphql-schema;charset=iso-8859-1.

Schema Generation - Unpublished Models

When Content Fragments are nested it can happen that a parent Content Fragment Model is published, but a referenced model is not.

When such happens, AEM generates an incomplete Schema for the parent Content Fragment Model. It means that the Fragment Reference, which depends on the unpublished model, is removed from the schema.

Fields

Within the schema, there are individual fields, of two basic categories:

• Fields that you generate.

  A selection of Data Types are used to create fields based on how you configure your Content Fragment Model. The field names are taken from the Property Name field of the Data Type.

  • There is also the Render As setting to consider, as users can configure certain data types. For example, a single-line text field can be configured to contain multiple single-line texts by choosing multifield from the dropdown.

• GraphQL for AEM also generates several helper fields.

  These fields are used to identify a Content Fragment, or to get more information about a content fragment.

Data Types

GraphQL for AEM supports a list of types. All the supported Content Fragment Model Data Types and the corresponding GraphQL types are represented:

Content Fragment Model - Data Type	GraphQL Type	Description
Single-line Text	String, [String]	Used for simple strings such as author names and location names.
Multiline Text	String	Used for outputting text such as the body of an article
Number	Float, [Float]	Used to display floating point number and regular numbers
Boolean	Boolean	Used to display checkboxes → simple true/false statements
Date And Time	Calendar	Used to display date and time in an ISO 8086 format. Depending on the type selected, there are three flavors available for use in AEM GraphQL: onlyDate, onlyTime, dateTime
Enumeration	String	Used to display an option from a list of options defined at model creation
Tags	[String]	Used to display a list of Strings representing Tags used in AEM
Content Reference	String	Used to display the path towards another asset in AEM
Fragment Reference	A model type Single field: Model - Model type, referenced directly Multifield, with one referenced type: [Model] - Array of type Model, referenced directly from array Multifield, with multiple referenced types: [AllFragmentModels] - Array of all model types, referenced from array with union type	Used to reference one, or more, Content Fragments of certain Model Types, defined when the model was created

Helper Fields

In addition to the data types for user-generated fields, GraphQL for AEM also generates several helper fields to help identify a Content Fragment, or to provide additional information about a Content Fragment.

These helper fields are marked with a preceding _ to distinguish between what has been defined by the user and what has been auto-generated.

Path

The path field is used as an identifier in AEM GraphQL. It represents the path of the Content Fragment asset inside the AEM repository. This path is chosen as the identifier of a content fragment, because it:

• is unique within AEM,
• can be easily fetched.

The following code displays the paths of all Content Fragments that were created based on the Content Fragment Model Person.

{
  personList {
    items {
      _path
    }
  }
}

To retrieve a single Content Fragment of a specific type, you must also determine its path first. For example:

{
  authorByPath(_path: "/content/dam/path/to/fragment/john-doe") {
    item {
      _path
      firstName
      name
    }
  }
}

See Sample Query - A Single Specific City Fragment.

Metadata

Through GraphQL, AEM also exposes the metadata of a Content Fragment. Metadata is the information that describes a content fragment, such as the following:

• the title of a content fragment
• the thumbnail path
• the description of a Content Fragment
• and the date it was created, among others.

Because Metadata is generated through the Schema Editor and as such does not have a specific structure, the TypedMetaData GraphQL type was implemented to expose the metadata of a Content Fragment. The TypedMetaData exposes the information grouped by the following scalar types:

Field
stringMetadata:[StringMetadata]!
stringArrayMetadata:[StringArrayMetadata]!
intMetadata:[IntMetadata]!
intArrayMetadata:[IntArrayMetadata]!
floatMetadata:[FloatMetadata]!
floatArrayMetadata:[FloatArrayMetadata]!
booleanMetadata:[BooleanMetadata]!
booleanArrayMetadata:[booleanArrayMetadata]!
calendarMetadata:[CalendarMetadata]!
calendarArrayMetadata:[CalendarArrayMetadata]!

Each scalar type represents either a single name-value pair or an array of name-value pairs, where the value of that pair is of the type it was grouped in.

For example, if you want to retrieve the title of a Content Fragment, this property is a String property, so you would query for all the String Metadata:

To query for metadata:

{
  personByPath(_path: "/content/dam/path/to/fragment/john-doe") {
    item {
      _path
      _metadata {
        stringMetadata {
          name
          value
        }
      }
    }
  }
}

You can view all the metadata GraphQL types if you view the Generated GraphQL schema. All model types have the same TypedMetaData.

See Sample Query for Metadata - List the Metadata for Awards titled GB.

Variations

The _variations field has been implemented to simplify querying the variations that a Content Fragment has. For example:

{
  personByPath(_path: "/content/dam/path/to/fragment/john-doe") {
    item {
      _variations
    }
  }
}

See Sample Query - All Cities with a Named Variation.

GraphQL Variables

GraphQL permits variables to be placed in the query. For more information, see GraphQL documentation for Variables.

For example, to get all Content Fragments of type Article that have a specific variation, you can specify the variable variation in GraphiQL.

### query
query GetArticlesByVariation($variation: String!) {
    articleList(variation: $variation) {
        items {
            _path
            author
            _variations
        }
    }
}

### in query variables
{
    "variation": "uk"
}

GraphQL Directives

In GraphQL, there is a possibility to change the query based on variables, called GraphQL Directives.

For example there you can include the adventurePrice field in a query for all the AdventureModels, based on a variable includePrice.

### query
query GetAdventureByType($includePrice: Boolean!) {
  adventureList {
    items {
      adventureTitle
      adventurePrice @include(if: $includePrice)
    }
  }
}

### in query variables
{
    "includePrice": true
}

Filtering

You can also use filtering in your GraphQL queries to return specific data.

Filtering uses a syntax based on logical operators and expressions.

The most atomic part is a single expression that can be applied to the content of a certain field. It compares the content of the field with a given constant value.

For example, the following expression would compare the content of the field with the value some text, and succeed if the content equals the value. Otherwise, the expression fails.:

{
  value: "some text"
  _op: EQUALS
}

The following operators can be used to compare fields to a certain value:

Operator	Types	The expression succeeds if …
EQUALS	String, ID, Boolean	… the value is the same as the content of the field
EQUALS_NOT	String, ID	… the value is not the same as the content of the field
CONTAINS	String	… the content of the field contains the value ({ value: "mas", _op: CONTAINS } matches Christmas, Xmas, master, …)
CONTAINS_NOT	String	… the content of the field does not contain the value
STARTS_WITH	ID	… the ID starts with a certain value ({ value: "/content/dam/", _op: STARTS_WITH matches /content/dam/path/to/fragment, but not /namespace/content/dam/something
EQUAL	Int, Float	… the value is the same as the content of the field
UNEQUAL	Int, Float	… the value is not the same as the content of the field
GREATER	Int, Float	… the content of the field is greater than the value
GREATER_EQUAL	Int, Float	… the content of the field is greater than or equal to the value
LOWER	Int, Float	… the content of the field is lower than the value
LOWER_EQUAL	Int, Float	… the content of the field is lower than or equal to the value
AT	Calendar, Date, Time	… the content of the field is the same as the value (including timezone setting)
NOT_AT	Calendar, Date, Time	… the content of the field is not the same as the value
BEFORE	Calendar, Date, Time	… the point in time denoted by the value is before the point in time denoted by the content of the field
AT_OR_BEFORE	Calendar, Date, Time	… the point in time denoted by the value is before or at the same point in time denoted by the content of the field
AFTER	Calendar, Date, Time	… the point in time denoted by the value is after the point in time denoted by the content of the field
AT_OR_AFTER	Calendar, Date, Time	… the point in time denoted by the value is after or at the same point in time denoted by the content of the field

Some types also let you specify additional options that modify how an expression is evaluated:

Option	Types	Description
_ignoreCase	String	Ignores the case of a string, for example, a value of time matches TIME, time, tImE, …
_sensitiveness	Float	Allows a certain margin for float values to be considered the same (to work around technical limitations due to the internal representation of float values; should be avoided, as this option might have a negative impact on performance

Expressions can be combined to a set with the help of a logical operator (_logOp):

• OR - the set of expressions succeed if at least one expression succeeds
• AND - the set of expressions succeed if all expressions succeed (default)

Each field can be filtered by its own set of expressions. The expression sets of all fields mentioned in the filter argument are eventually combined by its own logical operator.

A filter definition (passed as the filter argument to a query) contains:

• A subdefinition for each field (the field can be accessed through its name, for example, there’s a lastName field in the filter for the lastName field in the Data (field) Type)
• Each subdefinition contains the _expressions array, providing the expression set, and the _logOp field that defines the logical operator the expressions should be combined with
• Each expression is defined by the value (value field) and the operator (_operator field) the content of a field should be compared to

You can omit _logOp if you want to combine items with AND and _operator if you want to check for equality, because these values are defaults.

The following example demonstrates a full query that filters all persons that have a lastName of Provo or containing sjö, independent of the case:

{
  authorList(filter: {
    lastname: {
      _logOp: OR
      _expressions: [
        {
          value: "sjö",
          _operator: CONTAINS,
          _ignoreCase: true
        },
        {
          value: "Provo"
        }
      ]
    }
  }) {
    items {
      lastName
      firstName
    }
  }
}

While you can also filter on nested fields, it is not recommended, as it might lead to performance issues.

For further examples, see:

• details of the GraphQL for AEM extensions

• Sample Queries using this Sample Content and Structure

  • And the Sample Content and Structure prepared for use in sample queries

• Sample Queries based on the WKND Project

Sorting

This feature allows you to sort the query results according to a specified field.

The sorting criteria:

• is a comma-separated list of values representing the field path
  • the first field in the list defines the primary sort order
    • the second field is used if two values of the primary sort criterion are equal
    • the third field is used if the first two criteria are equal, and so on.
  • dotted notation, i.e field1.subfield.subfield and so on…
• with an optional order direction
  • ASC (ascending) or DESC (descending); as default ASC is applied
  • the direction can be specified per field; this ability means that you can sort one field in ascending order, another one in descending order (name, firstName DESC)

For example:

query {
  authorList(sort: "lastName, firstName") {
    items {
      firstName
      lastName
    }
  }
}

And also:

{
  authorList(sort: "lastName DESC, firstName DESC") {
    items {
        lastName
        firstName
    }
  }
}

You can also sort on a field within a nested fragment, using the format of nestedFragmentname.fieldname.

For example:

query {
  articleList(sort: "authorFragment.lastName")  {
    items {
      title
      authorFragment {
        firstName
        lastName
        birthDay
      }
      slug
    }
  }
}

Paging

This feature allows you to perform paging on query types that returns a list. Two methods are provided:

• offset and limit in a List query
• first and after in a Paginated query

List query - offset and limit

In a ...Listquery you can use offset and limit to return a specific subset of results:

• offset: Specifies the first data set to return
• limit: Specifies the maximum number of data sets to be returned

For example, to output the page of results containing up to five articles, starting from the fifth article from the complete results list:

query {
   articleList(offset: 5, limit: 5) {
    items {
      authorFragment {
        lastName
        firstName
      }
    }
  }
}

Paginated query - first and after

The ...Paginated query type reuses most of the ...List query type features (filtering, sorting), but instead of using offset/limit arguments, it uses the first/after arguments as defined by the GraphQL Cursor Connections Specification. You can find a less formal introduction in the GraphQL introduction.

• first: The n first items to return.
  The default is 50.
  The maximum is 100.
• after: The cursor that determines the beginning of the requested page. The item represented by the cursor is not included in the result set. The cursor of an item is determined by the cursor field of the edges structure.

For example, output the page of results containing up to five adventures, starting from the given cursor item in the complete results list:

query {
    adventurePaginated(first: 5, after: "ODg1MmMyMmEtZTAzMy00MTNjLThiMzMtZGQyMzY5ZTNjN2M1") {
        edges {
          cursor
          node {
            title
          }
        }
        pageInfo {
          endCursor
          hasNextPage
        }
    }
}

GraphQL for AEM - Summary of Extensions

The basic operation of queries with GraphQL for AEM adhere to the standard GraphQL specification. For GraphQL queries with AEM, there are a few extensions:

• If you require a single result:

  • use the model name; for example, city

• If you expect a list of results:

  • add List to the model name; for example, cityList
  • See Sample Query - All Information about All Cities

  You can then:

  • Sort the results

    • ASC : ascending
    • DESC : descending

  • Return a page of results using either:

    • A List query with offset and limit
    • A Paginated query with first and after

  • See Sample Query - All Information about All Cities

• The filter includeVariations is included in the List query type. To retrieve Content Fragment Variations in the query results, the includeVariations filter must be set to true.

  CAUTION

  The filter includeVariations cannot be used together with the system-generated field _variation.

• If you want to use a logical OR:

  • use _logOp: OR
  • See Sample Query - All Persons that have a name of “Jobs” or “Smith”

• Logical AND also exists, but is (often) implicit

• You can query on field names that correspond to the fields within the Content Fragment Model

  • See Sample Query - Full Details of a Company’s CEO and Employees

• In addition to the fields from your model, there are some system-generated fields (preceded by underscore):

  • For content:

    • _locale : to reveal the language; based on Language Manager

      • See Sample Query for multiple Content Fragments of a given locale

    • _metadata : to reveal metadata for your fragment

      • See Sample Query for Metadata - List the Metadata for Awards titled GB

    • _model : allow querying for a Content Fragment Model (path and title)

      • See Sample Query for a Content Fragment Model from a Model

    • _path : the path to your Content Fragment within the repository

      • See Sample Query - A Single Specific City Fragment

    • _reference : to reveal references; including inline references in the Rich Text Editor

      • See Sample Query for multiple Content Fragments with Prefetched References

    • _variation : to reveal specific Variations within your Content Fragment

      NOTE

      If the given variation does not exist for a Content Fragment, then the master variation is returned as a (fallback) default.

      CAUTION

      The system-generated field _variation cannot be used together with the filter includeVariations.

      • See Sample Query - All Cities with a Named Variation

    • _tags : to reveal the IDs of Content Fragments or Variations that contain tags; this list is an array of cq:tags identifiers.

      • See Sample Query - Names of All Cities Tagged as City Breaks
      • See Sample Query for Content Fragment Variations of a given Model that have a specific tag attached
      NOTE

      Tags can also be queried by listing the Metadata of a Content Fragment.

  • And operations:

    • _operator : apply specific operators; EQUALS, EQUALS_NOT, GREATER_EQUAL, LOWER, CONTAINS, STARTS_WITH

      • See Sample Query - All Persons that do not have a name of “Jobs”
      • See Sample Query - All Adventures where the _path starts with a specific prefix

    • _apply : to apply specific conditions; for example, AT_LEAST_ONCE

      • See Sample Query - Filter on an array with an item that must occur at least once

    • _ignoreCase : to ignore the case when querying

      • See Sample Query - All cities with SAN in the name, irrespective of case

• GraphQL union types are supported:

  • use ... on
    • See Sample Query for a Content Fragment of a specific Model with a Content Reference

• Fallback when querying nested fragments:

  • If the requested variation does not exist in a nested fragment, then the Master variation is returned.

CORS Filter

To access the GraphQL endpoint, configure a CORS policy in the customer Git repository. This configuration is done by adding an appropriate OSGi CORS configuration file for one or more desired endpoints.

This configuration must specify a trusted website origin alloworigin or alloworiginregexp for which access must be granted.

For example, to grant access to the GraphQL endpoint and persisted queries endpoint for https://my.domain you can use:

{
  "supportscredentials":true,
  "supportedmethods":[
    "GET",
    "HEAD",
    "POST"
  ],
  "exposedheaders":[
    ""
  ],
  "alloworigin":[
    "https://my.domain"
  ],
  "maxage:Integer":1800,
  "alloworiginregexp":[
    ""
  ],
  "supportedheaders":[
    "Origin",
    "Accept",
    "X-Requested-With",
    "Content-Type",
    "Access-Control-Request-Method",
    "Access-Control-Request-Headers"
  ],
  "allowedpaths":[
    "/content/_cq_graphql/global/endpoint.json",
    "/graphql/execute.json/.*"
  ]
}

If you have configured a vanity path for the endpoint, you can also use it in allowedpaths.

Referrer Filter

In addition to CORS configuration, a Referrer filter must be configured to allow access from third-party hosts.

This filter is done by adding an appropriate OSGi Referrer Filter configuration file that:

• specifies a trusted website host name; either allow.hosts or allow.hosts.regexp,
• grants access for this host name.

For example, to grant access for requests with the Referrer my.domain you can:

{
    "allow.empty":false,
    "allow.hosts":[
      "my.domain"
    ],
    "allow.hosts.regexp":[
      ""
    ],
    "filter.methods":[
      "POST",
      "PUT",
      "DELETE",
      "COPY",
      "MOVE"
    ],
    "exclude.agents.regexp":[
      ""
    ]
}

Authentication

See Authentication for Remote AEM GraphQL Queries on Content Fragments.

FAQs

Questions that have arisen:

1. Q: “How is the GraphQL API for AEM different from Query Builder API?”

   • A:
     “The AEM GraphQL API offers total control on the JSON output, and is an industry standard for querying content.
     In the future, AEM is planning to invest in the AEM GraphQL API.”

Tutorial - Getting Started with AEM Headless and GraphQL

Looking for a hands-on tutorial? Check out Getting Started with AEM Headless and GraphQL end-to-end tutorial illustrating how to build-out and expose content using AEM’s GraphQL APIs and consumed by an external app, in a headless CMS scenario.