Templating function arguments and return types

When using a templating function you pass some parameters and get something back. The types of these arguments and returned objects are the same in many methods, and it is helpful to know these types. Read the Javadoc of typical templating function return types even if you do not know Java. The Javadoc gives you an idea what else you could do with the returned objects.

Node and ContentMap

Some functions require Node, whereas others ask for ContentMap.

javax.jcr.Node

The type from the JCR API. Since JCR is a tree oriented data structure, this type is useful when you want to find other nodes above (parent, ancestors) or below (children) the current node.

info.magnolia.jcr.util.ContentMap

This Magnolia type is a wrapper for the above mentioned JCR node. ContentMap provides easy access to the node properties and is useful when you want to render these properties.

<h1>${content.title}</h1>

ContentMap and Node rendering context objects

  • The rendering context object content provides the current content node of the context as info.magnolia.jcr.util.ContentMap.

  • The rendering context object model.node provides the current content node of the context as javax.jcr.Node, see model. If you have no model but need this type, use cmsfn(content).

cmsfn provides methods to convert javax.jcr.Node to ContentMap and vice versa.

Node and ContentMap collections

Both types java.util.List and java.util.Collection either with Node or with ContentMap items might be required as arguments.

  • java.util.List<info.magnolia.jcr.util.ContentMap>

  • java.util.List<javax.jcr.Node>

  • java.util.Collection<javax.jcr.Node>

  • java.util.Collection<info.magnolia.jcr.util.ContentMap>

Keep in mind that List extends Collection. This means that if a Collection is required, you can pass a List, but this does not work the other way round.

cmsfn provides methods to convert Collection<Node> to List<ContentMap> and from Collection<ContentMap> to List<Node>.

Example: Get the children nodes of the node of the current nodes, convert the returned list of nodes into list of contentMap items and iterate over the list of contentMap items.

[#assign currentNode = cmsfn.asJCRNode(content)]
[#assign childrenNodesAsContentMaps = cmsfn.asContentMapList(cmsfn.children(currentNode, "mgnl:page"))]
[#list childrenNodesAsContentMaps as child ]
    <li>${child.title}</li>
[/#list]

Item, Asset, Folder, Map (of an asset), AssetRendition

itemKey of an asset

Some methods in damfn require a String argument called itemKey. An item key uniquely identifies an asset among different asset providers.

When JCR is used as asset provider, the item key is composed of jcr:<node-UUID>, for instance jcr:20d6e4e3-fe53-4b23-8d64-6e67a1c1667f. Typically you need to get the item key from a content node that is created when a component is saved in the JCR.

Example: A component node contains a reference to an image.

Component node with image reference

In a Java context, if you have an asset and want to know its item key as a String, use:

asset.getItemKey().asString()

In a FreeMarker context, if you have an asset and want to know its item key as a String, use:

[#assign itemKey = myAsset.getItemKey().asString()]

info.magnolia.dam.api.Item

Item is the common supertype of Asset and Folder. Some methods of the damfn will return Item.

info.magnolia.dam.api.Asset

An asset is a digital resource with associated metadata. This interface provides many methods that you may want to call directly within your script.

Example:

[#assign myAsset = damfn.getAsset("jcr", "/photos/dilbert.jpg")!]
get the link of an asset to display an image <img src="${myAsset.getLink()}"/> - when the asset is an image
or a download link: <a href="${myAsset.getLink()}">Link to the asset</a>

info.magnolia.dam.api.Folder

A Folder represents a structural item holding Assets. Depending on the provider, this can be directly mapped to the concept of folders/directories (JCR, FileSystems, and so on); for others this might map to the concept of albums, playlists, sets, and so on.

Example:

[#assign photosFolder = damfn.getFolder("jcr", "/photos")]
The folder ${photosFolder.name} contains the following images:
<ul>
[#list photosFolder.getChildren() as item]
    <li>${item.getName()}</li>
[/#list]
</ul>

Map of an asset and its metadata

The DAM templating functions (damfn) provide a method which returns a java.util.Map containing all the bean properties of the asset.

[#assign myAsset = damfn.getAsset("jcr", "photos/pool.jpg")!]
[#assign myAssetMap = damfn.getAssetMap(myAsset)]
fileSize: ${myAssetMap.fileSize}
folder: ${myAssetMap.caption?string}
name: ${myAssetMap.name}
title: ${myAssetMap.title}
caption: ${myAssetMap.caption}
copyright: ${myAssetMap.copyright}

See Asset for all public methods indicating the available properties.

Additionally, the map may contain further nested maps with the properties of classes implementing AssetMetadata. The metadata sub maps are collected under the key metadata.

If the asset is provided by JcrAssetProvider (that is, if the asset is derived from the JCR workspace dam), the following submaps are provided on the asset map:

Metadata class Key Composed key Example

info.magnolia.dam.api.metadata.DublinCore

dc

metadata.dc

myAssetMap.metadata.dc.format

info.magnolia.dam.api.metadata.MagnoliaAssetMetadata

mgnl

metadata.mgnl

myAssetMap.metadata.mgnl.width

 
[#assign myAsset = damfn.getAsset("jcr", "photos/pool.jpg")!]
[#assign myAssetMap = damfn.getAssetMap(myAsset)]
width: ${myAssetMap.metadata.mgnl.width}
format: ${myAssetMap.metadata.dc.format}

info.magnolia.dam.api.AssetRendition

AssetRendition is a variation on a asset, for a specific MimeType.

The renditions are defined per Theme in the Site. For instance the node /modules/site/config/themes/examples-theme/imaging/variations/small-square defines in the theme examples-theme a rendition named small-square.

Site and Theme

info.magnolia.module.site.Site

The Site object gives access to its appendant theme (if a theme is defined on the site) and some other objects as linked domains, mappings, and so on.

Example:

[#assign mySite=sitefn.site()]

info.magnolia.module.site.theme.Theme

Theme provides access to lists with CSS and JavaScript files which belong to the theme.

Example:

[#assign myTheme=sitefn.theme(sitefn.site())]

TemplateDefinition

Read Template definition to get an idea of what a template definition is. Some templating functions require a TemplateDefinition object as a parameter.

At least the template definition of the current template is always available as context object - see rendering context object def.

JsonBuilder

A JsonBuilder object is a builder for converting JCR nodes into JSON. The class offers many public methods to adapt the node structure and properties. JsonBuilder is the return types of all methods of jsonfn (JsonTemplatingFunctions) and of most of the methods of JsonBuilder. The #print method returns JSON as a string.

Using public method of returned objects

If you know the type of the returned object of a templating function, you can apply the public methods to the object to retrieve the return value of these methods. This works in almost every case but not for maps such as ContentMap.

Example:

[#assign currentNode = cmsfn.asJCRNode(content)]
<i>The path of the underlying jcr node in this context is ${currentNode.getPath()}.</i>

Notes:

  • Line 1: Assign an object of type javax.jcr.Node to the variable currentNode.

  • Line 2: Use the getPath() method which is a public method defined in javax.jcr.Node. It returns a String.

The script will print for instance: The path of the underlying jcr node in this context is /home/products.

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