AEM GraphQL API for use with Content Fragments graphql-api-for-use-with-content-fragments

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

AEM as a Cloud Service 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.
NOTE
GraphQL is currently used in two (separate) scenarios in Adobe Experience Manager (AEM) as a Cloud Service:
NOTE
For the latest information about Experience Manager APIs, please also visit Adobe Experience Manager as a Cloud Service APIs.

The GraphQL API 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, 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 to 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 information about the GraphQL API, see the following sections (amongst many other resources):

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

GraphQL Terminology graphql-terminology

GraphQL uses the following:

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

GraphQL Query Types graphql-query-types

With GraphQL you can perform queries to return either:

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

GraphQL Query Best Practices (Dispatcher and CDN) graphql-query-best-practices

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

  • they are cached
  • they are managed centrally by AEM as a Cloud Service
NOTE
Usually there is no dispatcher/CDN on author, so there is no gain in using persisted queries there; apart from testing them.

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 can hit limits (for example, the length of the URL) that can be avoided using Persisted Queries.

See Enable caching of persisted queries for further details.

NOTE
To allow direct, and/or POST, queries in the Dispatcher you can ask your System Administrator to:
NOTE
The ability to perform direct queries may be deprecated at some point in the future.

GraphiQL IDE graphiql-ide

You can test and debug GraphQL queries using the GraphiQL IDE.

Use Cases for Author, Preview and Publish use-cases-author-preview-publish

The use cases can depend on the type of AEM as a Cloud Service environment:

  • Publish environment; used to:

    • Query data for JS application (standard use-case)
  • Preview environment; used to:

    • Preview queries prior to deploying on the Publish environment
      • Query data for JS application (standard use-case)
  • Author environment; used to:

    • Query data for “content management purposes”:

      • GraphQL in AEM as a Cloud Service is currently a read-only API.
      • The REST API can be used for CR(u)D operations.

Permissions permission

The permissions are those required for accessing Assets.

GraphQL queries are executed 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 will not become part of the result set.

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

Schema Generation schema-generation

GraphQL is a strongly-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 do this, 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.

CAUTION
All the GraphQL schemas (derived from Content Fragment Models that have been Enabled) are readable through the GraphQL endpoint.
This means that you need to ensure that no sensitive data is available, as it could be leaked this way; for example, this includes information that could be present as field names in the model definition.

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:

    Content Fragment Model for use with GraphQL

  2. The corresponding GraphQL schema (output from GraphiQL automatic documentation):
    GraphQL Schema based on Content Fragment Model

    This 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 means that it is auto-generated each and every 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 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 will get updated.

    2. Whereas Model-1 will remain the same.

NOTE
This is important to note in case you want to do bulk updates on Content Fragment Models through the REST api, or otherwise.

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 will result in the output of the schema with the Content-type: text/x-graphql-schema;charset=iso-8859-1.

Schema Generation - Unpublished Models 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.

NOTE
The AEM UI prevents this happening, but if publishing is made programmatically, or with content packages, it can occur.

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

Fields 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 tab.

    • There is also the Render As setting to take into consideration, 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 drop-down list.
  • GraphQL for AEM also generates several helper fields.

Data Types 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, location names, and so on.
Multi line Text
String, [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 8601 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, [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 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 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. We have chosen this as the identifier of a Content Fragment, because it:

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

The following code will display the paths of all Content Fragments that were created based on the Content Fragment Model Author, as provided by the WKND tutorial.

{
  authorList {
    items {
      _path
    }
  }
}

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

{
  authorByPath(_path: "/content/dam/wknd-shared/en/contributors/sofia-sj-berg") {
    item {
      _path
      firstName
      lastName
    }
  }
}

See Sample Query - A Single Specific City Fragment.

Metadata metadata

Through GraphQL, AEM also exposes the metadata of a Content Fragment. Metadata is the information that describes a Content Fragment, such as the title of a Content Fragment, the thumbnail path, the description of a Content Fragment, the date it was created, amongst 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. 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, we know that this property is a String property, so we would query for all the String Metadata:

To query for metadata:

{
  authorByPath(_path: "/content/dam/wknd-shared/en/contributors/sofia-sj-berg") {
    item {
      _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.

NOTE
Difference between normal and array metadata
Keep in mind that StringMetadata and StringArrayMetadata both refer to what is stored in the repository, not how you retrieve them.
So for example, by calling the stringMetadata field, you would receive an array of all the metadata that was stored in the repository as a String , and if you call stringArrayMetadata you would receive an array of all the metadata that was stored in the repository as String[].

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

Variations variations

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

{
  authorByPath(_path: "/content/dam/wknd-shared/en/contributors/ian-provo") {
    item {
      _variations
    }
  }
}
NOTE
The _variations field does not contain a master variation, as technically the original data (referenced as Master in the UI) is not considered an explicit variation.

See Sample Query - All Cities with a Named Variation.

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

GraphQL Variables 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 Author in a specific variation (if available), you can specify the argument variation in GraphiQL.

GraphQL Variables

Query:

query($variation: String!) {
  authorList(variation: $variation) {
    items {
      _variation
      lastName
      firstName
    }
  }
}

Query Variables:

{
  "variation": "another"
}

This query will return the full list of authors. Authors without the another variation will fall back to the original data (_variation will report master in this case).

Apply a filter, if you want to restrict the list to authors that provide the specified variation (and skip authors that would fall back to the original data):

query($variation: String!) {
  authorList(variation: $variation, filter: {
    _variation: {
      _expressions: {
        value: $variation
      }
    }
  }) {
    items {
      _variation
      lastName
      firstName
    }
  }
}

GraphQL Directives 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.

GraphQL Directives

Query:

query GetAdventureByType($includePrice: Boolean!) {
  adventureList {
    items {
      title
      price @include(if: $includePrice)
    }
  }
}

Query Variables:

{
    "includePrice": true
}

Filtering 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 expression

{
  value: "some text"
  _op: EQUALS
}

would compare the content of the field with the value some text and succeeds if the content equals the value. Otherwise, the expression will fail.

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

Operator
Type(s)
The expression succeeds if …
EQUALS
String, ID, Boolean
… the value is exactly 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 } will match 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 will match /content/dam/path/to/fragment, but not /namespace/content/dam/something
EQUAL
Int, Float
… the value is exactly 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 exactly 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
Type(s)
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 will succeed if at least one expression succeeds
  • AND - the set of expressions will 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 will eventually be combined by its own logical operator.

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

  • A sub-definition 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 sub-definition 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, as these are the default values.

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:

Sorting sorting

This feature lets you 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 will define the primary sort order, the second field is used if two values of the primary sort criterion are equal, the third one if the first two criteria are equal, and so on.
    • dotted notation, that is, 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 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.

NOTE
This might have a negative impact on performance.

For example:

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

Paging paging

This feature lets you 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 list-offset-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
      }
    }
  }
}
NOTE
  • Paging requires a stable sort order to work correctly across multiple queries requesting different pages of the same result set. By default it uses the repository path of each item of the result set to make sure the order is always the same. If a different sort order is used, and if that sorting cannot be done at JCR query level, then there is a negative performance impact as the entire result set must be loaded into memory before the pages can be determined.

  • The higher the offset, the more time it will take to skip the items from the complete JCR query result set. An alternative solution for large result sets is to use the Paginated query with first and after method.

Paginated query - first and after paginated-first-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; note that 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
        }
    }
}
NOTE
  • By default, paging uses the UUID of the repository node representing the fragment for ordering to ensure the order of results is always the same. When sort is used, the UUID is implicitly used to ensure a unique sort; even for two items with identical sort keys.

  • Due to internal technical constraints, performance will degrade if sorting and filtering is applied on nested fields. Therefore it is recommended to use filter/sort fields stored at root level. This is also the recommended way if you want to query large paginated result sets.

Web-optimized image delivery in GraphQL queries web-optimized-image-delivery-in-graphql-queries

Web-optimized image delivery lets you use a Graphql query to:

  • Request a URL to a DAM asset image (referenced by a Content Reference)

  • Pass parameters with the query, so that a specific rendition of the image is automatically generated and returned

    note note
    NOTE
    The rendition specified is not stored in AEM Assets. The rendition is generated and held in cache for a short period.
  • Return the URL as part of the JSON delivery

You can use AEM to:

This means that the commands get applied during query execution, in the same way as URL parameters on GET requests for those images.

This lets you dynamically create image renditions for JSON delivery, which avoids having to manually create and store those renditions in the repository.

The solution in GraphQL means you can:

  • Request a URL: use _dynamicUrl on the ImageRef reference

  • Pass parameters: add _assetTransform to the list header where your filters are defined

Structure of the Transformation Request structure-transformation-request

AssetTransform (_assetTransform) is used to make the URL transformation requests.

The structure and syntax is:

  • format: an enumeration with all supported formats by its extension: GIF, PNG, PNG8, JPG, PJPG, BJPG, WEBP, WEBPLL or WEBPLY

  • seoName: a string that is used as file name instead of the node name

  • crop: a frame sub structure, if width or height is omitted then the height or width is used as the same value

    • xOrigin: the x origin of the frame and is mandatory
    • yOrigin: the y origin of the frame and is mandatory
    • width: the width of the frame
    • height: the height of the frame
  • size: a dimension sub structure, if width or height is omitted then the height or width is used as the same value

    • width: the width of the dimension
    • height: the height of the dimension
  • rotation: an enumeration of all supported rotations: R90, R180, R270

  • flip: an enumeration of HORIZONTAL, VERTICAL, HORIZONTAL_AND_VERTICAL

  • quality: an integer from 1–100 notating the percentage of the image quality

  • width: an integer that defines the width of the output image but is ignored by the Image Generator

  • preferWebp: a boolean that indicates if webp is preferred (default value is false)

The URL transform is available for all query types: by path, list or paginated.

Web-optimized image delivery with full parameters web-optimized-image-delivery-full-parameters

The following is a sample query with a full set of parameters:

{
  articleList(
    _assetTransform: {
      format:GIF
      seoName:"test"
      crop:{
        xOrigin:10
        yOrigin:20
        width:50
        height:45
      }
      size:{
        height:100
        width:200
      }
      rotation:R90
      flip:HORIZONTAL_AND_VERTICAL
      quality:55
      width:123
      preferWebp:true
    }
  ) {
    items {
      _path
      featuredImage {
        ... on ImageRef {
          _dynamicUrl
        }
      }
    }
  }
}

Web-optimized image delivery with a single query variable web-optimized-image-delivery-single-query-variable

The following example shows the use of a single query variable:

query ($seoName: String!) {
  articleList(
    _assetTransform: {
      format:GIF
      seoName:$seoName
      crop:{
        xOrigin:10
        yOrigin:20
        width:50
        height:45
      }
      size:{
        height:100
        width:200
      }
      rotation:R90
      flip:HORIZONTAL_AND_VERTICAL
      quality:55
      width:123
      preferWebp:true
    }
  ) {
    items {
      _path
      featuredImage {
        ... on ImageRef {
          _dynamicUrl
        }
      }
    }
  }
}

Web-optimized image delivery with multiple query variables web-optimized-image-delivery-multiple-query-variables

The following example shows the use of multiple query variables:

query ($seoName: String!, $format: AssetTransformFormat!) {
  articleList(
    _assetTransform: {
      format:$format
      seoName:$seoName
      crop:{
        xOrigin:10
        yOrigin:20
        width:50
        height:45
      }
      size:{
        height:100
        width:200
      }
      rotation:R90
      flip:HORIZONTAL_AND_VERTICAL
      quality:55
      width:123
      preferWebp:true
    }
  ) {
    items {
      _path
      featuredImage {
        ... on ImageRef {
          _dynamicUrl
        }
      }
    }
  }
}

Web-optimized image delivery request by URL web-optimized-image-delivery-request-url

If you save your query as a persisted query (for example, with the name dynamic-url-x) you can then execute the persisted query directly.

For example, to directly execute the previous samples (saved as persisted queries), use the following URLs:

  • Single Parameter; Persisted Query named dynamic-url-x

    • http://localhost:4502/graphql/execute.json/wknd-shared/dynamic-url-x;seoName=xxx

      The response will look like:

      Image Delivery using parameters

  • Multiple Parameters; Persisted Query named dynamic

    • http://localhost:4502/graphql/execute.json/wknd-shared/dynamic;seoName=billiboy;format=GIF;

      note caution
      CAUTION
      The trailing ;is mandatory to cleanly terminate the list of parameters.

Limitations of web-optimized image delivery web-optimized-image-delivery-limitations

The following limitations exist:

  • Modifiers applied to all images part of the query (global parameters)

  • Caching headers

    • No caching on author
    • Caching on publish - max-age of 10 minutes (cannot be changed by client)

GraphQL for AEM - Summary of Extensions graphql-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:

Querying the GraphQL endpoint from an External Website query-graphql-endpoint-from-external-website

To access the GraphQL endpoint from an external website you need to configure the:

Authentication authentication

See Authentication for Remote AEM GraphQL Queries on Content Fragments.

Limitations limitations

To protect against potential problems there are default limitations imposed on your queries:

  • The query cannot contain more than 1M (1024 * 1024) characters
  • The query cannot contain more than 15000 tokens
  • The query cannot contain more than 200000 whitespace tokens

You also need to aware of:

  • A field conflict error will be returned when your GraphQL query contains fields with the same name in two (or more) models:

    • So where:

      • Two (or more models) are used as possible references; when they are defined as an allowed Model Type in the Content Fragment reference.

      and:

      • These two models have fields having a common name; that means the same name occurs in both models.

      and

      • Those fields are of different data types.
    • For example:

      • When two (or more) fragments with different models (for example, M1, M2) are used as possible references (Content Reference or Fragment Reference) from another fragment; for example, Fragment1 MultiField/List

      • And these two fragments with different models (M1, M2) have fields with the same name, but different types.
        To illustrate:

        • M1.Title as Text
        • M2.Title as Text/MultiField
      • Then a field conflict error will occur if the GraphQL query contains the Title field.

FAQs 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.
      Moving forward, AEM is planning to invest in the AEM GraphQL API.

Tutorial - Getting Started with AEM Headless and GraphQL tutorial

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.

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