Content Fragment Models

Content Fragment Models in AEM define the structure of content for your content fragments, serving as a foundation of your headless content.

To use Content Fragment Models you:

1. Enable Content Fragment Model functionality for your instance
2. Create, and configure, your Content Fragment Models
3. Enable your Content Fragment Models for use when creating Content Fragments for use when creating Content Fragments
4. Allow your Content Fragment Models on the required Assets folders by configuring Policies.

Creating a Content Fragment Model

1. Navigate to Tools, Assets, then open Content Fragment Models.

2. Navigate to the folder appropriate to your configuration.

3. Use Create to open the wizard.

   CAUTION

   If the use of content fragment models have not been enabled, the Create option will not be available.

4. Specify the Model Title. You can also add Tags, a Description, and select Enable model to enable the model if required.

   

5. Use Create to save the empty model. A message will indicate the success of the action, you can select Open to immediately edit the model, or Done to return to the console.

Defining your Content Fragment Model

The content fragment model effectively defines the structure of the resulting content fragments using a selection of Data Types. Using the model editor you can add instances of the data types, then configure them to create the required fields:

1. Navigate to Tools, Assets, then open Content Fragment Models.

2. Navigate to the folder holding your content fragment model.

3. Open the required model for Edit; use either the quick action, or select the model and then the action from the toolbar.

   Once open the model editor shows:

   • left: fields already defined
   • right: Data Types available for creating fields (and Properties for use once fields have been created)
   NOTE

   When a field as Required, the Label indicated in the left pane will be marked with an asterix (*).

1. To Add a Field

   • Drag a required data type to the required location for a field:

     

   • Once a field has been added to the model, the right panel will show the Properties that can be defined for that particular data type. Here you can define what is required for that field.

     • Many properties are self-explanatory, for additional details see Properties.

     • Typing a Field Label will auto-complete the Property Name - if empty, and it can be manually updated afterwards.

       CAUTION

       When manually updating the property Property Name for a data type, note that names must contain only Latin characters, numerical digits and underscore “_” as special character.

       If models created in earlier versions of AEM contain illegal characters, please remove or update those characters.

     For example:

     

2. To Remove a Field

   Select the required field, then click/tap the trash-can icon. You will be asked to confirm the action.

   

3. Add all required fields, and define the related properties, as required. For example:

   

4. Select Save to persist the definition.

Data Types

A selection of data types is available for defining your model:

• Single line text
  • Add one, or more, fields of a single line of text; the maximum length can be defined
• Multi line text
  • A text area that can be Rich Text, Plain Text or Markdown
• Number
  • Add one, or more, numerical fields
• Boolean
  • Add a boolean checkbox
• Date and time
  • Add a date and/or time
• Enumeration
  • Add a set of checkbox, radio button(s), or dropdown fields
• Tags
  • Allows fragment authors to access and select areas of tags
• Content Reference
  • References other content, of any type; can be used to create nested content
  • If an image is referenced, you can opt to show a thumbnail
• Fragment Reference
  • References other content fragments; can be used to create nested content
  • The data type can be configured to allow fragment authors to:
    • Edit the referenced fragment directly.
    • Create a new content fragment, based on the appropriate model
• JSON Object
  • Allows the content fragment author to enter JSON syntax into the corresponding elements of a fragment.
    • To allow AEM to store direct JSON that you have copy/pasted from another service.
    • The JSON will be passed through, and output as JSON in GraphQL.
    • Includes JSON syntax-highlighting, auto-complete and error-highlighting in the content fragment editor.
• Tab Placeholder

  • Allows the introduction of tabs for use when editing the Content Fragment content.
    This will be shown as a divider in the model editor, separating sections of the list of content data types. Each instance represents the start of a new tab.
    In the fragment editor each instance will appear as a tab.

    NOTE

    This data type is purely used for formatting, it is ignored by the AEM GraphQL schema.

Properties

Many properties are self-explanatory, for certain properties additional details are below:

• Property Name

  When manually updating this property for a data type, note that names must contain only Latin characters, numerical digits and underscore “_” as special character.

  CAUTION

  If models created in earlier versions of AEM contain illegal characters, please remove or update those characters.

• Render As
  The various options for realizing/rendering the field in a fragment. Often this allows you to define whether the author will see a single instance of the field, or will be allowed to create multiple instances.

• Field Label
  Entering a Field Label will autogenerate a Property Name, which can then be manually updated if required.

• Validation
  Basic validation is available by mechanisms such as the Required property. Some data types have addition validation fields. See Validation for further details.

• For the data type Multi line text it is possible to define the Default Type as either:

  • Rich Text
  • Markdown
  • Plain Text

  If not specified, the default value Rich Text is used for this field.

  Changing the Default Type in a content fragment model will only take effect on an existing, related, content fragment after that fragment is opened in the editor and saved.

• Unique
  Content (for the specific field) must be unique across all content fragments created from the current model.

  This is used to ensure that content authors cannot repeat content already added in another fragment of the same model.

  For example, a Single line text field called Country in the Content Fragment Model cannot have the value Japan in two dependent Content Fragments. A warning will be issued when the second instance is attempted.

  NOTE

  Uniqueness is ensured per language root.

  NOTE

  Variations can have the same unique value as variations of the same fragment, but not the same value as used in any variation of other fragments.

• See Content Reference for more details about that specific data type and its properties.

• See Fragment Reference (Nested Fragments) for more details about that specific data type and its properties.

Validation

Various data types now include the possibility to define validation requirements for when content is entered in the resulting fragment:

• Single line text
  • Compare against a predefined regex.
• Number
  • Check for specific values.
• Content Reference
  • Test for specific types of content.
  • Only assets of specified file size or smaller can be referenced.
  • Only images within a predefined range of width and/or height (in pixels) can be referenced.
• Fragment Reference
  • Test for a specific content fragment model.

Using References to form Nested Content

Content Fragments can form nested content, using either of the following data types:

• Content Reference

  • Provides a simple reference to other content; of any type.
  • Can be configured for a one or multiple references (in the resulting fragment).

• Fragment Reference (Nested Fragments)

  • References other fragments, dependent on the specific models specified.

  • Allows you to include/retrieve structured data.

    NOTE

    This method is of particular interest in conjunction with Headless Content Delivery using Content Fragments with GraphQL.

  • Can be configured for one or multiple references (in the resulting fragment)…

Content Reference

The Content Reference allows you to render content from another source; for example, image or content fragment.

In addition to standard properties you can specify:

• The Root Path for any referenced content
• The content types that can be referenced
• Limitations for file sizes
• If an image is referenced:
  • Show Thumbnail
  • Image restraints of height and width

Fragment Reference (Nested Fragments)

The Fragment Reference references one, or more, content fragments. This feature of particular interest when retrieving content for use in your app, as it allows you to retrieve structured data with multiple layers.

For example:

• A model defining details for an employee; these include:
  • A reference to the model that defines the employer (company)

type EmployeeModel {
    name: String
    firstName: String
    company: CompanyModel
}

type CompanyModel {
    name: String
    street: String
    city: String
}

In addition to standard properties you can define:

• Render As:

  • multifield - the fragment author can create multiple, individual, references

  • fragmentreference - allows the fragment author to select a single reference to a fragment

• Model Type
  Multiple models can be selected. When authoring the Content Fragment any referenced fragments must have been created using these models.

• Root Path
  This specifies a root path for any fragments referenced.

• Allow Fragment Creation

  This will allow the fragment author to create a new fragment based on the appropriate model.

  • fragmentreferencecomposite - allows the fragment author to build a composite, by selecting multiple fragments

  

Content Fragment Model - Properties

You can edit the Properties of a Content Fragment Model:

• Basic
  • Model Title
  • Tags
  • Description
  • Upload Image

Enabling or Disabling a Content Fragment Model

For full control over the use of your Content Fragment Models they have a status that you can set.

Enabling a Content Fragment Model

Once a model has been created it needs to be enabled so that it:

• Is available for selection when creating a new Content Fragment.
• Can be referenced from within a Content Fragment Model.
• Is available to GraphQL; so the schema is generated.

To enable a Model that is flagged as either:

• Draft : mew (never enabled).
• Disabled : has been specifically disabled.

You use the Enable option from either:

• The top toolbar, when the required Model is selected.
• The corresponding Quick Action (mouse-over the required Model).

Disabling a Content Fragment Model

A model can also be disabled so that:

• The model is no longer available as a basis for creating new Content Fragments.
• However:
  • The GraphQL schema keeps being generated and is still queryable (to avoid impacting JSON API).
  • Any Content Fragments based of the model can still be queried and returned from the GraphQL endpoint.
• The model cannot be referenced anymore, but existing references are kept untouched, and can still be queried and returned from the GraphQL endpoint.

To disable a Model that is flagged as Enabled you use the Disable option from either:

• The top toolbar, when the required Model is selected.
• The corresponding Quick Action (mouse-over the required Model).

Allowing Content Fragment Models on your Assets Folder

To implement content governance, you can configure Policies on Assets folder to control which Content Fragment Models are allowed for Fragment creation in that folder.

To configure the Policies for Allowed Content Fragment Models:

1. Navigate and open Properties for the required Assets folder.

2. Open the Policies tab, where you can configure:

   • Inherited from <folder>

     Policies are automatically inherited when creating new child folders; the policy can be reconfigured (and the inheritance broken) if sub-folders need to allow models different to the parent folder.

   • Allowed Content Fragment Models by Path

     Multiple models can be allowed.

   • Allowed Content Fragment Models by Tag

     Multiple models can be allowed.

   

3. Save any changes.

The Content Fragment Models allowed for a folder are resolved as follows:

• The Policies for Allowed Content Fragment Models.
• If empty, then try to determine the policy using the inheritance rules.
• If the inheritance chain does not deliver a result, then look at the Cloud Services configuration for that folder (also first directly and then via inheritance).
• If none of the above deliver any results, then there are no allowed models for that folder.

Deleting a Content Fragment Model

To delete a content fragment model:

1. Navigate to Tools, Assets, then open Content Fragment Models.

2. Navigate to the folder holding your content fragment model.

3. Select your model, followed by Delete from the toolbar.

   NOTE

   If the model is referenced a warning will be given. Take action appropriately.

Publishing a Content Fragment Model

Content fragment models need to be published when/before any dependent content fragments are published.

To publish a content fragment model:

1. Navigate to Tools, Assets, then open Content Fragment Models.

2. Navigate to the folder holding your content fragment model.

3. Select your model, followed by Publish from the toolbar.
   The published status will be indicated in the console.

   NOTE

   If you publish a content fragment for which the model has not yet been published, a selection list will indicate this and the model will be published with the fragment.

Unpublishing a Content Fragment Model

Content fragment models can be unpublished if they are not referenced by any fragments.

To unpublish a content fragment model:

1. Navigate to Tools, Assets, then open Content Fragment Models.

2. Navigate to the folder holding your content fragment model.

3. Select your model, followed by Unpublish from the toolbar.
   The published status will be indicated in the console.

If you try to unpublish a model that is currently used by one or more fragments, then an error warning will inform you of this:

The message will suggest that you check the References panel to investigate further:

Locked (Published) Content Fragment Models

This feature provides governance for Content Fragment Models that have been published.

The Challenge

• Content Fragment Models determine the schema for GraphQL queries in AEM.

  • AEM GraphQL schemas are created as soon as a Content Fragment Model is created, and they can exist on both author and publish environments.

  • Schemas on publish are the most critical as they provide the foundation for live delivery of Content Fragment content in JSON format.

• Problems can occur when Content Fragment Models are modified, or in other words edited. This means that the schema changes, which in turn may affect existing GraphQL queries.

• Adding new fields to a Content Fragment Model should (typically) not have any detrimental effects. However, modifying existing data fields (for example, their name) or deleting field definitions, will break existing GraphQL queries when they are requesting these fields.

The Requirements

• To make users aware of the risks when editing models that are already used for live content delivery - in other words, models that have been published).

• Also, to avoid unintended changes.

Either of these might break queries if the modified models are re-published.

The Solution

To address these issues, Content Fragment Models are locked into a READ-ONLY mode on author - as soon as they have been published. This is indicated by Locked:

When the model is Locked (in READ-ONLY mode), you can see the contents and structure of models but you cannot edit them.

You can manage Locked models from either the console, or the model editor:

• Console

  From the console, you can manage the READ-ONLY mode with the Unlock and Lock actions in the toolbar:

  

  • You can Unlock a model to enable edits.

    If you select Unlock a warning will be shown, and you must confirm the Unlock action:
    

    You can then open the model for editing.

  • You can also Lock the model afterwards.

  • Re-publishing the model will immediately put it back into Locked (READ-ONLY) mode.

• Model Editor

  • When you open a model that is locked you will be warned, and presented with three actions: Cancel, View Read Only, Edit:

    

  • If you select View Read Only you can see the content and structure of the model:

    

  • If you select Edit you can edit and save your updates:

    

    NOTE

    There may still a warning at the top, but that is when the model is already in use by existing Content Fragments.

  • Cancel will return you to the console.