YAML inherit and include

This page describes the Magnolia-specific directives !inherit, !include and !override. You can use these directives to reuse configuration in YAML file-based configuration. !include is supposed to be used when reusing an arbitrary resource, whereas !inherit comes handy when extending a definition.

YAML `include`

Use !include to add a reusable chunk. Include a YAML fragment on a sub-level of your new definition or include a complete YAML definition on top of your new definition. You can also modify the included part of the definition.

Reference the file you want to include by its resource path. The path to such a resource has the following pattern: /<module-name>/path/to/the/reusable/chunk.yaml.

Best practice

Typically, you include YAML snippets which are not a proper definition. Do not add these snippets to the folders which are meant for definitions (templates, dialogs, app). Instead, add these snippets to a folder which is not scanned, for instance /<your-module>/includes/.

If your !include file is not working, check that the first line in the included YAML file does not have any indentation.

Syntactic variants of the directive

The !include directive exists since Magnolia 5.4, which introduced configuration by YAML. With the release of 5.5.6, the directive's syntax has changed slightly. While the old syntax still works, the new one makes it possible to modify and override the included part of the definition. The new syntax uses a colon : instead of the space between !include and the path to the resource.

	Syntax	Requires version	Functions
Deprecated syntax.	`!include <path/to/a–ressource.yaml>`	Magnolia 5.4+	simple include
New syntax.	`!include:<path/to/a–ressource.yaml>`	Magnolia 5.5.6+	simple include, include and modify

A generic recipe

Prepare a fragment of definition which is suitable to be reused in many other item definitions.
Include a resource with the !include directive. The included resource can contain a fragment or a complete definition.
Modify parts of the included definition.

Examples

Simple include

Include one tab in the form and all the action definitions in the action in a dialog definition. This example works with both the old (deprecated) and the new syntax.

Includable files:

/module-a/includes/categorization-tab.yaml

name: tabCategories
label: Categories
fields:
  - name: categories
    label: Categories
    class: info.magnolia.ui.form.field.definition.MultiValueFieldDefinition
    label: Select category
    field:
      name: linkField
      class: info.magnolia.ui.form.field.definition.LinkFieldDefinition
      targetWorkspace: category
      appName: categories
      identifierToPathConverter:
        class: info.magnolia.ui.form.field.converter.BaseIdentifierToPathConverter
  - name: blackOrWhite
    label: Black or white
    class: info.magnolia.ui.form.field.definition.SelectFieldDefinition
    options:
      - name: black
        value: black
        selected: true
        label: Black
      - name: white
        value: white
        label: White

/module-a/includes/common-actions.yaml

  commit:
    class: info.magnolia.ui.admincentral.dialog.action.SaveDialogActionDefinition
  cancel:
    class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition

A dialog file which includes:

/module-a/dialogs/components/another-component.yaml

form:
  label: another-component
  tabs:
    - name: tabMain
      label: Main
      fields:
        - name: title
          label: Text
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          label: Title
 
    # an include within a list, here adding a complete tab
    - !include:/module-a/includes/categorization-tab.yaml
 
# an include within a map, here adding the actions for the root (map) item "actions"
actions: !include:/module-a/includes/common-actions.yaml

Include and modify a fragment

Include one tab in the form and all the action definitions in the action in a dialog definition. This is similar as in the example above. Additionally, modify the included parts of the definition.

This example works only with the new syntax (see syntactic variants).

Includable files:

/module-a/includes/categorization-tab.yaml

name: tabCategories
label: Categories
fields:
  - name: categories
    label: Categories
    class: info.magnolia.ui.form.field.definition.MultiValueFieldDefinition
    label: Select category
    field:
      name: linkField
      class: info.magnolia.ui.form.field.definition.LinkFieldDefinition
      targetWorkspace: category
      appName: categories
      identifierToPathConverter:
        class: info.magnolia.ui.form.field.converter.BaseIdentifierToPathConverter
  - name: blackOrWhite
    label: Black or white
    class: info.magnolia.ui.form.field.definition.SelectFieldDefinition
    options:
      - name: black
        value: black
        selected: true
        label: Black
      - name: white
        value: white
        label: White

/module-a/includes/common-actions.yaml

  commit:
    class: info.magnolia.ui.admincentral.dialog.action.SaveDialogActionDefinition
  cancel:
    class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition

A dialog file which includes:

/module-a/dialogs/components/lazy-component.yaml

form:
  label: lazy-component
  tabs:
    # an include within a list, here adding a complete tab
    - !include:/module-a/includes/categorization-tab.yaml
      label: Yo! 1-tab-only!
      fields:
        # modify properties of the field blackOrWhite which comes from the include
        - name: blackOrWhite
          label: Choose color
# an include within a map, here adding the actions for the root (map) item "actions"
actions: !include:/module-a/includes/common-actions.yaml
  # add another action to those which already exist from the include
  doit:
    label: Same as cancel
    class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition

Line 6: Modify the label of the included tab.
Lines 9 and 10: Modify the label of the blackOrWhite field from the include.
Lines 14 to 16: Add another action to the imported actions.

Include a complete file and modify

Create a dialog based on a dialog from the basic page template of the mtk module. Remove its second tabMeta tab. This task is similar to the example above in the modify section, but instead of inheriting, you include.

/module-a/dialogs/pages/aa-page.yaml

!include:/mtk/dialogs/pages/basic.yaml
form:
  tabs:
    - name: tabMeta
      fields: !override

YAML `inherit`

As the name suggests, with this directive you inherit from an existing registered definition item in order to create a new definition item. Registered items can originate from YAML files, JCR configurations or even from Blossom Java code.

It is not a good idea to inherit from a definition which resides in the same module as the dependent one. This can lead to inconsistencies.

You can inherit only on the root level - which means you can inherit a complete app but not a subapp. Modify the new item according to your needs.

Registered definition items are known to a registry and can be seen in the Definitions app. Every registered definition item has an "identifier" which is unique among all items of the same type within their registry. Some of the items are defined by name, others by ID. Reference the item to inherit by its identifier.

Inherited items are inherited according to their state known by the registry. (For instance, if an items has been decorated, the registry knows its decorated state. Hence inheriting a decorated item inherits the decorated state of the item.)

Click here to expand for a list of definition item examples and their identifiers.

Item definition type	Identifier type	Example identifier
Template definitions	ID	mtk:components/link
Dialog definitions	ID	mtk:components/textImage
App definitions	Name	definitions-app
Theme definitions	Name	travel-demo-theme
Renderer definitions	Name	freemarker

Module dependencies due to `!inherit`

When using !inherit, you may rely on a definition item which is configured in another module. In this case you must take care of the loading order. If you rely on another module, make sure it is loaded upfront. Use module dependencies to define the loading order of the modules.

The module dependencies define the order in which modules are loaded during startup. For example, if module-a depends on module-b, module-b will be loaded before module-a. The order becomes important, for example, if both module-a and module-b decorate the same definition or if module-a inherits a definition from module-b.

Module dependencies can be defined within a module descriptor.

A generic recipe

On the first line of your YAML definition, use the !inherit directive followed by a colon ( : ) and the identifier of the definition you want to inherit from.
Modify the inherited definition.

Examples

Inherit and override a renderer

A new definition:

/module-a/renderers/json.yaml

!inherit:freemarker
contentType: application/json

The new renderer named json inherits everything from the freemarker renderer but has a different contentType.

Inherit and override a template definition

The original definition you inherit from:

/module-a/templates/components/a-component.yaml

title: a-component
renderType: freemarker
templateScript: /module-a/templates/components/a-component.ftl
dialog: module-a:components/a-component
modelClass: info.magnolia.module.jsmodels.rendering.JavascriptRenderingModel
 
parameters:
  color: blue
  size: 50

A new definition which inherits:

/module-b/templates/components/b-component.yaml

!inherit:module-a:components/a-component
title: b-component
description: This is a b-bombastic component to test cool YAML features!
subtype: dummy-components
parameters: !override

Line 1: Inherit.
Line 2: Override the title property.
Lines 3 and 4: Add more properties.
Line 5: Suppress the parameters property.

The module descriptor of module-b

/module-b/module.yaml

version: 1.0
dependencies:
  module-a:
    version: 1.0/*

By setting this dependency, we make sure that module-a is loaded before module-b. As a result, the b-component, which depends on a-component, can be initialized properly.

Modifying reused configuration

Reused configuration originating from !inherit or from !include (when using the new !include syntax) can be modified. You can:

Add additional properties and modify properties originating from !include or !inherit. This will merge the included or inherited node with the modifications.
Use !override to completely ignore the properties of an inherited or included node. As a consequence, you have to add further properties to the given node.

YAML `override`

The !override directive ignores the properties of the node to which the directive has been applied. You have to specify all of the required properties of the overridden definition node.

Example:

A definition to inherit or to include Inherit Inherit and override

/module-a/templates/pages/l-page.yaml

title: L page
templateScript: /mtk/templates/pages/basic.ftl
renderType: freemarker
dialog: module-a:pages/l-page
visible: true
 
areas:
  main:
    availableComponents:
      textImage:
        id: mtk:components/textImage
      teaser:
        id: mtk:components/teaser
      image:
        id: mtk:components/image
      link:
        id: mtk:components/link

/module-a/templates/pages/xxl-page.yaml

!inherit:module-a:pages/l-page
title: XXL page
dialog: module-a:pages/xxl-page
 
areas:
  main:
    availableComponents:
      html:
        id: mtk:components/html

/module-a/templates/pages/xs-page.yaml

!inherit:module-a:pages/l-page
title: XXL page
dialog: module-a:pages/xxl-page
 
areas:
  main:
    availableComponents:
      html:
        id: mtk:components/html

The resulting definition merges the inherited defintion and the modifications area, giving five available components in the main area. The resulting definition ignores all the properties of availableComponents of the inherited definition, thus allowing only one available component in the main area.

Overriding list items

Due to the syntax of a YAML list, you cannot apply !override to a list item. To bypass this constraint, use a YAML map instead of a list to apply override to an item. Even if the definition class expects a list, the YAML file can define the item with a map.

Example:

A definition to inherit or to include Inherit

/module-a/dialogs/pages/l-page.yaml

form:
  label: Page properties
  tabs:
    - name: tabMain
      label: L page
      fields:
        - name: title
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          i18n: true
          label: title
        - name: navigationTitle
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          i18n: true
          label: navigation title
        - name: windowTitle
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          i18n: true
          label: window title
    - name: tabMeta
      label: Meta Data
      fields:
        - name: keywords
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          i18n: true
          label: keywords
          rows: 3
        - name: description
          class: info.magnolia.ui.form.field.definition.TextFieldDefinition
          i18n: true
          label: description
          rows: 5
 
actions:
  commit:
    class: info.magnolia.ui.admincentral.dialog.action.SaveDialogActionDefinition
  cancel:
    class: info.magnolia.ui.admincentral.dialog.action.CancelDialogActionDefinition

/module-a/dialogs/pages/xs-page.yaml

!include:/module-a/dialogs/pages/l-page.yaml
form:
  tabs:
    tabMeta: !override
    tabMain:
      fields:
        title: !override
          required: true
          class: info.magnolia.ui.form.field.definition.RichTextFieldDefinition
          label: Title ...

Both tabs and fields are defined with a list. To define these properties, it would have been valid to use the map syntax instead. To apply !override to the tabMeta tab and the title field, we have used the map syntax here.

Preserving the order of nodes

The order of nodes as defined in a decoration via YAML !override is preserved. This is useful especially if the only change needed to the existing configuration of nodes is their order. Previously, when providing a new config with the !override flag, the config would be picked up by the system, but any change in the order of the nodes (at the level of the !override) would not be respected.

For example, the list view in the workbench of the Tours app may be adjusted with the following definition decoration placing the Path column before the Name column:

/stories-app/decorations/tours/apps/tours.yaml

subApps:
  browser:
    workbench:
      contentViews:
        list:
          columns: !override
            path:
            name:

Page tree

YAML inherit and include

YAML include

Syntactic variants of the directive

A generic recipe

Examples

Simple include

Include and modify a fragment

Include a complete file and modify

YAML inherit

Module dependencies due to !inherit

A generic recipe

Examples

Inherit and override a renderer

Inherit and override a template definition

Modifying reused configuration

YAML override

Overriding list items

Preserving the order of nodes

YAML `include`

YAML `inherit`

Module dependencies due to `!inherit`

YAML `override`