Link field

LinkFieldDefinition renders a text field and a browse button that allows the user to select an item from a configured app. The link field is used to select targets inside Magnolia, for example a page to tease, an asset to render an image, etc.. The link field stores a reference to the selected item.

The link field allows you to choose items from any content app, including non-JCR apps. 

class: info.magnolia.ui.form.field.definition.LinkFieldDefinition

The central property when defining a link field is appName - the name of the Magnolia app to choose the item from. The target app is responsible for providing a view that is suitable for selecting the item. When the target app is a content app, the workbench in the browser subapp is a suitable view and it is used by default. For more complex apps like the Assets app,  a choose dialog is configured in the app to browse the contents. 

Link field properties

Simple link field definition

form:
 tabs:
    - name: tabImage
      label: Image 
      fields:
        - name: image
          class: info.magnolia.ui.form.field.definition.LinkFieldDefinition
          targetWorkspace: dam
          appName: assets
          label: Select image
          identifierToPathConverter:
            class: info.magnolia.dam.app.assets.field.translator.AssetCompositeIdKeyTranslator
          contentPreviewDefinition:
            contentPreviewClass: info.magnolia.dam.app.ui.field.DamFilePreviewComponent

You can use common field properties and the following properties in a link field definition:

Properties:

Using link fields with JCR-agnostic target apps

The link field also allows you to choose items from non-JCR apps.

To understand the process when choosing an item from a content app via link field, basic knowledge of the Content app framework and the nature of LinkField

is necessary.

Things to note about LinkField:

• It extends a custom Vaadin field,
• It stores a value which must be String.
• It has a callback ( ChooseDialogCallback
• ). 
• When choosing an item, the method #onItemChosen(actionName, chosenValue) is triggered on the callback. The parameter choosenValue is of type Object and is the corresponding ItemId of the item of the content app. (See ItemIds and Items). 

Depending on the implementation of the content app, the ItemId may be a String or a more complex Object. A well-known ItemId is JcrItemId . The callback properly handles JcrItemId, and if it is another type, String.valueOf(chosenValue) is saved to the link field.

    protected ChooseDialogCallback createChooseDialogCallback() {
        return new ChooseDialogCallback() {
 
            @Override
            public void onItemChosen(String actionName, final Object chosenValue) {
                String newValue = null;
                if (chosenValue instanceof JcrItemId) {
                    String propertyName = definition.getTargetPropertyToPopulate();
                    try {
                        javax.jcr.Item jcrItem = JcrItemUtil.getJcrItem((JcrItemId) chosenValue);
                        if (jcrItem.isNode()) {
                            final Node selected = (Node) jcrItem;
                            boolean isPropertyExisting = StringUtils.isNotBlank(propertyName) && selected.hasProperty(propertyName);
                            newValue = isPropertyExisting ? selected.getProperty(propertyName).getString() : selected.getPath();
                        }
                    } catch (RepositoryException e) {
                        log.error("Not able to access the configured property. Value will not be set.", e);
                    }
                } else {
                    newValue = String.valueOf(chosenValue);
                }
                linkField.setValue(newValue);
                linkField.getSelectButton().setEnabled(true);
            }
 
            @Override
            public void onCancel() {
                linkField.getSelectButton().setEnabled(true);
            }
        };
    }
}

If LinkField does not work for your custom content app, create a custom link field. See Custom fields for more.