Creating a FAQ Application

This tutorial will show you how to build a Frequently Asked Questions (FAQs) Application much like the one you can find on the FAQ page. This is a very simple application that makes use of XWiki's classes, properties, and objects. It also uses a technique that you may frequently use as the basis for several different kinds of applications.

All through this tutorial you should refer to the XWiki Data Model for information on XWiki's data model. You might also use the XWiki Scripting Guide to get you started with scripting in XWiki and manipulating XWiki objects. In addition, this tutorial will introduce the concepts of Authoring Templates and Page Design Sheets, patterns that you will find particularly useful in creating XWiki applications. Completing this tutorial is a recommended prerequisite for anyone who wants to build custom applications on the XWiki engine.

Application Overview

The FAQ application allows users to post a question by entering the question into a simple form field and then submitting the form. The question then appears in a list along with all other questions that have been previously posted. Users can click on the questions to view both the question and answer in a consistently styled view. If the question has not yet been answered, any user can post an answer to the question by editing the page. In edit mode, the page will display a web form that is always consistent for every FAQ page.

Let us begin by taking a look at what we are going to build. The system has the following views. Click any view link below to preview a screenshot. (Note: Firefox users can middle click or click down on the mouse scroll-wheel to open the links in a new tab.)

Authoring Templates and Page Design Sheets

An Authoring Template is a template for creating documents of a specific type. Unlike a regular content page in edit mode with one field for freeform editing, an Authoring Template presents a custom set of form fields for creating a document with specific type of data. These form elements are defined by the properties of a class.

In object oriented programming, remember that a class is a template for an object. Using the analogy of a cookie cutter, the class is the cookie cutter and the objects are the actual cookies. An Authoring Template provides one way to represent a class visually so that users can fill out a form to set unique properties (values in form fields). When the user submits the form, they are creating a unique object of the class type.

Precisely, an Authoring Template is a prototype document used to create other specific instances of documents of the same type, along with a method of exposing the creation process to the user: the properties edit form. Remember that a XWiki Document can contain objects and this is the case of an authoring template: it is a XWiki Document with an empty object of a specific class, which is duplicated to create more and more documents based on that model, using the data inserted by the user in the editing form as specific values for the particular object instance in the current copy.

The Page Design Sheet is like a style sheet that defines each document will look when it is rendered. Even though the unique object instances will have different values for their properties, they will always have a consistent presentation display because they will be rendered through the Page Design Sheet. The XWiki API available in scripting languages provides a mechanism that will help us use the same sheet for both editing and view modes. We will see how we can achieve this once we get to the FAQ Design Sheet section.

Get Set with the Class Editor Wizard

Five pages have been developed which collectively make up a Class Editor Wizard application that can assist you in this process. Your first task is to see if you have these pages in your XWiki already. If so, you'll make a link to the wizard app so that you can always access it easily from an administrative page. If you do not have all five pages of the wizard, you'll need to make the missing pages using code provided by this tutorial.

  • Enter a search query for the keyword "XWikiClasses". This should return a document called XWikiClasses in the XWiki space (i.e. XWiki.XWikiClasses). This is the first of the five pages that make up the wizard and it is the main entry page to the wizard application.
  • Take a moment to bookmark this page or, even better, create a link to it from an administrative page so you can access it more easily in the future.
  • Navigate to the XWiki.XWikiClasses page.

Now, you just need to verify that you have the other four pages that make up the wizard app and create them if you do not. Check if the following classes are listed on the XWikiClasses page:

  • ClassSheet
  • ClassTemplate
  • ClassItemSheet
  • ClassItemTemplate

If they're not showing up or if they are showing up but with question marks, you do not have the pages in your XWiki database. You can either use this provided ClassWizard.xar to import the documents in your wiki (see the Import guide in the XWiki Administration Guide for details on this operation) or copy the page contents from the links below and paste them into the respective pages in your XWiki instance (create them as children of the XWikiClasses page) to ensure that you have all the parts that make up the wizard:

Once you have all of these pages in place, you are ready to start building your FAQs application. 

Keep in mind that you should always use the Wiki editing mode when editing scripts inside documents.

Create the FAQ Class

  • On the Class Editor wizard entry page (XWiki.XWikiClasses), under the heading "Create a new Class", enter the following web space and class name:
    • Web: FAQs
    • Class: FAQ

CreateANewClass.png

  • Click the "Create this Class" button. You should then see a code page with the following code:
## replace Main with the Space where you want your documents to be created
## replace the default parent with the one of your choice
## Save this template using the ?Save? button
#set( $class = $doc.name.substring(0,$doc.name.indexOf("Class")))
#set($defaultparent = "XWiki.${class}Class")
#set($defaultweb = "Main")
#includeForm("XWiki.ClassSheet")

In the code, change the word "Main" with the name of the space where you want you FAQ pages to be created as the commented instructions in the page code suggest. Replace the word "Main" with the word "FAQs". The line of code should now look like this:

#set($defaultweb = "FAQs")

Click the "Save & View" button. The class is now created and you should the be looking at a page titled "Class: FAQClass" that looks like this:

png]

Add Properties to the Class

Under the page title, you should see the words "The first thing to do is to Edit the Class to add properties to it." So, let's just follow those instructions!

  • Click on the 'Edit the Class' link; a blank page will be displayed.
  • Note that the link trail in the header is something like "Welcome to the Class Editor > FAQClass". Even though the page is blank, this shows you are indeed on the class page.

In our document, we'll store both a question and an answer. So we need a property for each.

  • Enter the text question in the Property Name field of the Class Editor panel (in the column on the right).
  • Choose a TextArea type for the property and then click the 'Add Property' button. The TextArea will ultimately give us a multi-line text field in our authoring template.
  • Configure this property with the following values (actually, if you are using the current XWiki version, you don't need to change anything else but the Pretty name – all the rest are the default values):

QuestionProperty.png

  • Now add a property called answer in the same way that you did for the 'question' property (choosing TextArea for the property type).
  • Choose it from the property list on the left and configure this property with the same values as the "question" property, except for the name and pretty name which will, obviously, match the new property we're creating.
  • When you are done adding and configuring the properties, click the 'Save & View' button.

Create the Page Design Sheet

  • After the previous step you are now on the FAQClass page which should look like this:

FAQClass1.png

  • Click the first button to create the document sheet (the Page Design Sheet). This sheet determines how your page objects will be rendered to the user. You should see the following page code for the document sheet:
11. You can modify this page to customize the presentation of your object
11. at first you should keep the default presentation.
11. Save this template using the save button.

1 Document $doc.name

## Change class name to your class name
#set($class = $doc.getObject("XWiki.MyClass").xWikiClass)
#set($hasProps = false)
#foreach($prop in $class.properties)
  #if($velocityCount == 1)
    #set($hasProps = true)
    <dl>
  #end
<dt> ${prop.prettyName} </dt>
<dd>$doc.display($prop.getName())</dd>
#end
#if($hasProps)
  </dl>
#end
  • Change the class name XWiki.MyClass in the code to FAQs.FAQClass so that the line looks like this:
## Change class name to your class name
#set($class = $doc.getObject("FAQs.FAQClass").xWikiClass)
  • Let's take a moment now and analyze the code: with the line we just modified we retrieve the FAQs.FAQClass from the wiki and then we iterate through all its properties and display their values for the current document in a definition list. As we mentioned, XWiki provides a mechanism that help us create sheets used for both view and edit mode: this is the display function used in the line: 
<dd>$doc.display($prop.getName())</dd>

 It detects the current mode (edit or view) and displays the property referenced by it's argument as the mode dictates: for view, it is the value of the property, for edit it is a form field that will allow the user to edit it. This way we can use a single Design Sheet for both displaying and editing our FAQs. See the XWiki API reference and XWiki Scripting pages for more details.

  • Click 'Save & View'.

Create the Authoring Template

  • Search for the keywords 'FAQs.FAQClass' and click on the document to open it in XWiki again, or click the FAQClass in the breadcrumbs. The document should look like this:

FAQClass2.png

  • Notice that now, there is a link for the FAQClassSheet in place of the button that was previously there. 
  • Click on the 'Create the document template' button. The Authoring Template will be created with the following page code:
## Replace MyName with the real class name.
## Save this template using the save button.
#includeForm("XWiki.MyNameClassSheet")
  • As the comments instruct, change the words MyName with FAQ so that instead of having XWiki.MyNameClassSheet, you will have FAQs.FAQClassSheet. In this case, we changed the space preceding the page name also because we want all of our FAQ page objects to reside in a unique wiki web space.
  • Click 'Save & Continue' to save the document. Remember that all our documents will be copies of the Authoring Template used as a prototype so the content we just saved will be copied in all our FAQs documents and will execute the Design Sheet code in the context of the current document. See the dedicated page for more information regarding this technique.
  • Now, we need to associate the prototype object with this document to turn it into a true authoring template.
  • On the right side, in the Choose editor list, click Objects.
  • In the Add Object panel on the right, select FAQs.FAQClass from the drop-down and then click 'Add Object from this Class'. The Question and Answer form fields appear on the page.
  • Click 'Save & View'. Congratulations; You just created an Authoring Template!
  • Click the FAQs.FAQClass link in the header breadcrumb trail. As you can see, you are almost done!

FAQClass3.png

Test the Application

Now let's just create a new document in our application to test it out. 

  • Under the "Create a new document" header, enter a document title in the Document field and click Create. For example, enter What is the meaning of life?.
  • You can then enter your question in longer form using the Question field on the template, like this:

FAQSheetEdit.png

  • Click Save & View and then you will see the newly created document, like this:

FAQSheetView.png

  • Open the FAQClass document again. You can now see that the FAQ documents you are creating will build in a list on the main entry page to the application, like this:

FAQClass4.png

Displaying the FAQ Questions as summary

If you want to display the FAQ question instead of the FAQ document name in the summary area, you can proceed as follow:

  • Edit the content of the FAQs.FAQClass page
  • Replace the #includeForm("XWiki.ClassSheet") with the content of the XWiki.ClassSheet (go to the XWiki.ClassSheet, edit the content and paste it instead of the #includeForm command
  • Then, after the 
#foreach ($item in $xwiki.searchDocuments($sql))

 command add the following line 

#set ($faq=$xwiki.getDocument(${item}))

 and replace the 

[$item]

 with 

[${faq.display("question")}>${item}]

 The line we added retrieves the document using the document name while the line we replaced displays the "question" property for the document instead of the document name.

  • Click "Save & View" and enjoy your new FAQ application.

Finally, link to the FAQs.FAQClass page

We don't want our users to have to search for this page using the search engine, so finally pick a spot on your Wiki and make a user-friendly link to FAQs.FAQClass. For example:

[Frequently Asked Questions (FAQs) > FAQs.FAQClass]

Conclusion

This tutorial has shown how to use the Class Wizard app and it has detailed the concepts of classes, objects, properties and introduced the authoring templates and page design sheets. You may also have learned a little bit about Velocity scripting in documents. You can use these basic concepts to build custom applications at the document or presentation layer of XWiki without having to compile or deploy code.

As always, please take the time to make this document better for other users if you find ways that it can be improved as you read it for the first time.

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