When a user assigns a document type to a document, the user is required to fill out the fields defined by the metadata set of the document type. This encourages users not to forget to enter important information about their documents. For example, you could create a copyrighted document type and require users to enter a license for all “copyrighted” documents. More importantly, document types and metadata sets can make it easier to find documents. The values that users enter into the fields determined by their document type’s metadata set become searchable entities within the portal. You can use Liferay’s search portlet to search for these terms. Document types and metadata sets are accessible from the Manage button at the top of the Documents and Media portlet window.
Figure 5.3: Navigate to the Document Types Dialog Box by clicking *Manage* → *Document Types*.
You can add a new document type using the Add button at the top of the dialog box. To do so, you need to define one or more metadata sets to associate with your document type. When creating a new document type, you can define Main Metadata Fields or select Additional Metadata Fields. Main metadata fields are directly tied to their document type and cannot be made available to other document types. Additional metadata fields, by contrast, can be defined independently and can be used in many different document types. You can differentiate the document types that implement the same additional metadata set by defining different main metadata fields for them. However, additional metadata fields need to be defined and saved before creating a document type that will implement them.
As an example, we could create a document type called Syllabus and define a metadata set. What metadata should we associate with syllabi? Let’s choose for our syllabi to have course title, professor, semester, course description, and course requirements fields. All syllabi in our portal should maintain entries for these fields. This ensures that a syllabus shows up in a portal search if its course title, professor or semester is searched for. Since we don’t want to use our metadata set for any document type other than Syllabus, let’s create our metadata set under the Main Metadata Fields area. Alternatively, we could create our metadata set independently using Manage → Metadata Sets → Add and then select it as an Additional Metadata Field.
You can view, edit, or add metadata sets from the Manage → Metadata window. A metadata set consists of a group of fields. If you click the Add button, you can use same UI for defining a metadata set that you used in the Add Document Type window.
Figure 5.4: Adding a New Metadata Set is easier than ever with Liferay's advanced editor.
Make sure the Fields tab is selected on the left. Then, to define a metadata set, just choose fields to use from the area on the left and drag and drop them into the area on the right. The drag and drop interface allows for nested fields so you need to be careful about where you drop the fields. Default values, mouse-over tips, widths, and other settings can be configured for most fields. To configure these settings, just click on a field from the area on the right. This automatically selects the Settings tab on the left. Alternatively, you can access the Settings tab by clicking the fields Settings button (wrench). Then double-click on a value to edit. Liferay supports the following kinds of fields for metadata sets:
Boolean: is a checkbox.
Date: lets you enter a date. A valid date format is required for the date field, but you don’t have to enter a date manually. When you select the date field a mini-calendar pops up which you can use to select a date.
Decimal: lets you enter a decimal number. The value will be persisted as a double.
Documents and Media: lets you select a file from one of the portal’s Documents and Media libraries.
HTML: an area that uses a WYSIWYG editor to enhance the content.
Integer: lets you enter an integer. The value will be persisted as an int.
Link to Page: lets you link to another page in the same site.
Number: lets you enter a decimal number or an integer. The value will be persisted either as a double or an int, depending on the type of input.
Radio: displays several clickable options. The default number is three but this is customizable. Only one option can be selected at a time.
Select: is just like the radio field except that the options are hidden and have to be accessed from a drop-down menu.
Text: lets you enter a single line of text.
Text Box: is just like the text field except you can enter multiple lines of text or separate paragraphs.
Remember that metadata sets created independently are reusable. Once they have been created they can be included in any number of document types as additional metadata sets. Next, let’s take a look at tags. Tags can be attached to most forms of web content that can be created in Liferay, including documents.