Wiki source code of Creating a FAQ Application

Version 93.2 by Vincent Massol on 2017/01/17

version	line-number	content
52.1	1	{{box cssClass="floatinginfobox" title="Contents"}}
	2	{{toc/}}
	3	{{/box}}
1.1	4
83.1	5	This tutorial will show you how to build a Frequently Asked Questions (FAQs) [[Application>>platform:Features.Applications]] much like the one you can find on the [[FAQ page>>xwiki:FAQ.WebHome]]. This is a very simple application that makes use of XWiki's [[classes, properties, and objects>>platform:DevGuide.DataModel\|\|anchor="HXWikiClasses2CObjects2CandProperties"]]. It also uses a technique that you may frequently use as the basis for several different kinds of applications.
1.1	6
80.1	7	= Prerequisites for following the tutorial =
54.2	8
	9	You should have [[installed XWiki>>AdminGuide.Installation]] and have a [[basic understanding of how to use it>>Features.WebHome]].
	10
54.3	11	All through this tutorial you should refer to the [[XWiki Data Model>>DevGuide.DataModel]] for information on XWiki's data model. You might also use the [[XWiki Scripting Guide>>DevGuide.Scripting]] 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.
	12
48.2	13	= Application Overview =
1.1	14
42.1	15	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 the same for every FAQ page.
1.1	16
80.1	17	Let us begin by taking a look at what we are going to build. The new application will have the following views:
1.1	18
84.1	19	* The FAQ [[Class>>xwiki:FAQ.WhatIsAClass]]
80.1	20	{{image reference="FAQsSummary.png"/}}
84.1	21	* An FAQ entry in View mode
80.1	22	{{image reference="FAQSheetView.PNG"/}}
84.1	23	* An FAQ entry in Edit mode
80.1	24	{{image reference="FAQSheetEdit.PNG"/}}
1.1	25
48.2	26	= Authoring Templates and Page Design Sheets =
48.1	27
14.1	28	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.
1.1	29
48.1	30	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.
1.1	31
14.1	32	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.
1.1	33
31.6	34	The Page Design Sheet is like a style sheet that defines what each document will look like when 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.
1.1	35
48.2	36	= Go to the Class Editor Wizard =
31.6	37
62.2	38	Five pages, which collectively make up a [[XClass application>>extensions:Extension.XClass Application]] (a.k.a Class Wizard or Class Editor Wizard), have been developed to assist you in this process. Those page are technical pages hidden by default. To navigate to the wizard home page, go to your profile page, select the Preferences tab, edit the page and choose to view Hidden Documents. 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 homepage of the class wizard creator: you are now ready to start building your FAQs application.
1.1	39
48.2	40	= Create the FAQ Class =
1.1	41
84.3	42	* On the Class Editor wizard entry page (XWiki.XWikiClasses), under the heading "Create a new data type", in the "Title" field, enter ##FAQ## as the name of the page to create:(((
	43	{{image reference="CreateANewClass1.png"/}}
48.4	44	)))
84.3	45	* As you can see in the Breadcrumb below the new page will be created at location ##XWiki > FAQ##. Now it would be nice to have it created in a new location such as ##FAQ > FAQ##. Since the ##FAQ## parent doesn't exist we cannot use the Tree picker button. Thus click the Pencil button as shown in the following image and replace ##XWiki## by ##FAQ##:(((
	46	{{image reference="CreateANewClass2.png"/}}
	47	)))
	48	* In technical terms you're creating a page named ##FAQ## located in a space also called ##FAQ## and the reference is ##FAQ.FAQ##.
80.1	49	* Click the "Create this Class" button. You should then see a page with the following content:(((
48.1	50	{{code language="none"}}
41.1	51	{{velocity}}
60.6	52	## Replace the default space with the space where you want your documents to be created.
41.1	53	## Replace the default parent with the one of your choice and save the document.
	54	##
60.6	55	#set($defaultSpace = $doc.space)
	56	#set($defaultParent = $doc.fullName)
41.1	57	{{/velocity}}
48.1	58	{{/code}}
48.4	59	)))
14.1	60
80.1	61	In the code, change the word "$doc.space" with the name of the space where you want you FAQ pages to be created as the commented instructions in the page code suggest.
	62	The line of code should look like this:
1.1	63
52.1	64	{{code language="none"}}
	65	#set($defaultSpace = 'FAQ')
	66	{{/code}}
14.1	67
80.1	68	You can also change the default parent of the new FAQ documents that are going to be created. To do so, replace the "$defaultParent" variable with the name of your document.
	69	The line of code should look like this:
1.1	70
52.1	71	{{code language="none"}}
	72	#set($defaultParent = 'FAQ.WebHome')
	73	{{/code}}
1.1	74
42.1	75	Click the "Save & View" button. The class is now created and you should be looking at a page titled "Class: FAQ" that looks like this:
28.1	76
80.1	77	{{image reference="FAQClass1.PNG"/}}
29.1	78
48.2	79	= Add Properties to the Class =
1.1	80
48.3	81	Under the page title, you should see the words "The class does not have any properties yet. You can use the //__class editor__// to define them." Let's just follow those instructions!
1.1	82
80.1	83	* Click on the 'class editor' link
92.2	84	* Note that the link trail in the header is something like "Wiki Home / FAQ / FAQ Class". This shows you that you are indeed on the FAQ class page in Class edit mode.
1.1	85
92.3	86	In our document, we'll store both a //question// and an //answer//. So we need to create a property for each of them.
1.1	87
80.1	88	* Enter the text //question// in the "name" field
	89	* Choose a TextArea type for the property and then click on "Add". The TextArea will ultimately give us a multi-line text field in our authoring template.(((
	90	{{image reference="AddQuestionProperty.PNG"/}}
48.4	91	)))
80.1	92	* Click on the "+" icon to expand the options for the newly created property
	93	* Change the value of the "Pretty Name" field to "Question"(capital Q):(((
	94	{{image reference="QuestionProperty.PNG"/}}
48.4	95	)))
80.1	96	* Now create another property called //answer// the same way that you did for the previous "question" property (choose TextArea for the property type)
	97	* Expand it from the property list and change the value of the "Pretty Name" field to "Answer"
	98	* When you are done adding and configuring the properties, click the "Save & View" button
1.1	99
48.2	100	= Create the Page Design Sheet =
1.1	101
52.1	102	* After the previous step you are now on the FAQClass page which should look like this:(((
80.1	103	{{image reference="FAQClass2.PNG"/}}
48.4	104	)))
80.1	105	* Click the first button ("Create the document sheet") to create the document sheet (the Page Design Sheet). This sheet determines how your page's objects will be rendered to the user. The document is automatically created.
92.4	106	* You should see a warning message with the text "The sheet is not bound to the class so it won't be applied automatically when a page that has an object of this class is displayed". Click the "Bind the sheet to the class" link that appears after the text. What this does is important:
	107	** It adds an object of type ##XWiki.ClassSheetBinding## to the ##FAQ.FAQClass" document. Basically it ties the FAQ Class to the Sheet.
	108	It's because of this object that users will be sent to form edition mode when editing FAQ entries**
	109	* Now click on "View the sheet document". This takes you to the ##FAQ.FAQSheet## page which you can edit in wiki mode and see its default content:(((
48.1	110	{{code language="none"}}
41.1	111	{{velocity}}
	112	## You can modify this page to customize the presentation of your object.
	113	## At first you should keep the default presentation and just save the document.
14.1	114
41.1	115	#set($class = $doc.getObject('FAQ.FAQClass').xWikiClass)
12.1	116	#foreach($prop in $class.properties)
41.1	117	; $prop.prettyName
	118	: $doc.display($prop.getName())
12.1	119	#end
41.1	120	{{/velocity}}
48.1	121	{{/code}}
92.5	122	)))Let's take a moment now and analyze this code:(((
14.1	123
92.4	124	* The first line retrieves the ##FAQ.FAQClass## from the wiki
42.1	125	* Then we iterate through all its properties and display their values for the current document in a definition list.
	126
80.1	127	As we mentioned, XWiki provides a mechanism that helps us create sheets used for both View and Edit mode.
	128	This is the display function used in the line:
48.1	129
83.1	130	{{code language="none"}}
	131	: $doc.display($prop.getName())
	132	{{/code}}
48.1	133
80.1	134	It detects the current mode (Edit or View) and displays the property referenced by its argument as the mode dictates:
	135
42.1	136	* In view mode it will display the value of the property
	137	* In edit mode it will display a form field that will allow the user to edit it
	138
48.1	139	This way we can use a single Design Sheet to both display and edit our FAQ entries. See the [[XWiki API reference>>DevGuide.API]] and [[XWiki Scripting>>DevGuide.Scripting]] pages for more details about this.
42.1	140
	141	* Click "Save & View"
92.5	142	)))
42.1	143
48.2	144	= Create the Authoring Template =
1.1	145
92.6	146	* Navigate back to the ##FAQ.FAQClass## document (you can use the arrows in the breadcrumb to do so). The document should look like this:(((
80.1	147	{{image reference="FAQClass3.PNG"/}}
48.4	148	)))
80.1	149	* Click on the "Create the document template" button. The Authoring Template will be automatically created.
1.1	150
92.8	151	Note that earlier, we changed the space name preceding the page name because we wanted all of our FAQ pages to reside in a space named FAQ. Remember that all our documents will be copies of the Authoring Template used as a prototype so the content 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>>DevGuide.IncludeInVelocity]] for more information regarding this technique.
42.1	152
92.8	153	Now we need to associate the prototype object with this document to turn it into a true authoring template:
	154
	155	* If you're on the template page, navigate back to the ##FAQ.FAQClass## document.
	156	* At the bottom of the page, look for the following warning message: "The template does not contain an object of type FAQClass. Add a FAQ object to the template »."
80.1	157	* Click on "Add a FAQ object to the template »":(((
	158	{{image reference="FAQObject.png"/}}
	159	)))
83.1	160
92.8	161	Next, we want to remove the title for the newly created template:
83.1	162
92.8	163	* Navigate to the ##FAQ.FAQTemplate## document (you can click on the "View the template page (FAQ / FAQ Template)" link for doing that for example.
83.1	164	* Edit this document in Wiki mode
	165	* Inside the Title field you have "FAQ Template" written -> delete this text
	166	* Save & View
	167
	168	This step is needed so that all of our future entries don't have "FAQ Template" as their title.
	169
	170	Congratulations: you just created an Authoring Template! You're almost done now.
92.8	171
80.1	172	{{image reference="FAQClass4.PNG"/}}
52.1	173
48.2	174	= Create a home page for the FAQ application =
38.1	175
42.1	176	You want your users to be able to see a list of all existing questions and answers and to add new questions. The best way to do this is to put the FAQ application in its own space and to use that space's homepage to display existing questions.
1.1	177
93.1	178	Thus we now need to create the ##FAQ.WebHome## page
1.1	179
93.1	180	* Click on "FAQ" in the breadcrumb to navigate to ##FAQ.WebHome## and notice that the page doesn't exist.
	181	* Edit it in wiki mode
	182	* Type in the title "FAQs"
	183
48.2	184	== Displaying existing FAQ entries ==
1.1	185
80.1	186	You have 2 options when it comes to displaying existing FAQ entries:
55.2	187
80.1	188	1. Use the livetable component
	189	1. Write custom code in order to display them
	190
55.2	191	=== Using the Livetable component ===
	192
	193	In this section, we will show how to use the [[Livetable Macro>>extensions:Extension.Livetable Macro]] to display the existing questions and answers.
	194
56.1	195	The livetable component will give users the ability to easily list and filter through existing FAQ documents. The macro is made of 3 parts:
	196
	197	* The list of columns: for each entry, we will display the question, the date when it was created and a special column that lets users quickly modify entries
	198	* The properties of each column: for each column, we will define how it should be displayed, whether it should link to the entry and whether it should be filterable
	199	* The livetable options: those are options related to the display of the livetable (in this case we will to display a tag cloud and 10 rows by default)
	200
	201	Here is the resulting code:
	202
	203	{{code language="none"}}
	204	{{velocity}}
55.2	205	#set($columns = ["question", "doc.creationDate", "_actions"])
	206	#set($columnsProperties = {
	207	"question" : { "type" : "text", "link" : "view", "html" : "true", "sortable":true },
56.1	208	"_actions" : {"actions": ["edit","delete"]}
55.2	209	})
	210	#set($options = {
	211	"className":"FAQ.FAQClass",
	212	"translationPrefix" : "faq.",
	213	"tagCloud" : true,
	214	"rowCount": 10
	215	})
	216	#livetable("faq" $columns $columnsProperties $options)
57.1	217	{{/velocity}}
55.2	218	{{/code}}
	219
93.1	220	* Copy this code and paste it as Wiki content (inside ##FAQ.WebHome##)
56.1	221	* Click "Save and View"
	222	* New FAQ entries will now be displayed on the page once you create them
	223
93.1	224	The ##FAQ.WebHome## page should look similar to this:
80.1	225
	226	{{image reference="FAQsLivetable.png"/}}
	227
93.1	228	Notice how there are some translation keys displayed inside the livetable. Let's create a translations document and change those keys to actual text:
83.1	229
93.1	230	* Create a new page inside the FAQ space called Translations, i.e. at ##FAQ.Translations## (using the "+" button)
80.1	231	* Edit it in Wiki mode and paste this content inside:(((
	232	{{code language="none"}}
	233	faq.question=Question
	234	faq.doc.creationDate=Creation Date
	235	faq._actions=Actions
83.1	236	{{/code}}
	237	)))
93.1	238	* Click "Save & View"
	239	* Edit it again in Object mode and add a new ##XWiki.TranslationDocumentClass## object to mark the page as a page containing translations. Make sure to select the right scope. Using "Global" means the translations would be visible to all wikis (and it requires having Programming Rights!) and "Wiki" means it's visible to the current wiki only. Choose "Wiki" as the scope.
	240	* Click "Save & View" again
80.1	241
93.1	242	Now the ##FAQ.WebHome## page should look like this (notice the translations instead of the keys):
80.1	243
	244	{{image reference="FAQsLivetableWithTranslations.png"/}}
	245
55.2	246	=== Using custom code ===
	247
42.1	248	You will need to write the following code:
1.1	249
93.2	250	* A XWQL query that will find all your FAQ documents. Check the [[Query API documentation>>extensions:Extension.Query Module]] to know more about it.
93.1	251	** The XWQL query looks for all documents that have a ##FAQ.FAQClass## object other than the template
42.1	252	** If no document has been created yet, a warning message is displayed
59.2	253	* A piece of velocity code to display all those documents
42.1	254	** The velocity code loops in that list
	255	** For each item, the full document is loaded in memory so that values can be retrieved from it
	256	** For each document, the question is retrieved and displayed as a link towards the FAQ entry
1.1	257
80.1	258	Here is the resulting code:
1.1	259
48.1	260	{{code language="none"}}
42.1	261	= Existing FAQ entries =
1.1	262
42.1	263	{{velocity}}
93.1	264	#set($xwql = "from doc.object(FAQ.FAQClass) as faq where doc.fullName <> 'FAQ.FAQTemplate'")
	265	#set($results = $services.query.xwql($xwql).execute())
42.1	266	#if($results.empty)
49.1	267	No FAQ has been created yet!
42.1	268	#else
49.1	269	#foreach ($item in $results)
	270	#set($faq = $xwiki.getDocument($item))
51.1	271	* [[${faq.display("question").replace("<p>", "").replace("</p>", "")}>>${item}]]
49.1	272	#end
42.1	273	#end
	274	{{/velocity}}
48.1	275	{{/code}}
1.1	276
93.1	277	* Copy this code and paste it as Wiki content inside ##FAQ.WebHome##
42.1	278	* Click "Save and View"
	279	* New FAQ entries will now be displayed on the page once you create them
1.1	280
93.1	281	The ##FAQ.WebHome## page should look similar to this:
80.1	282
	283	{{image reference="FAQsCustomCode.png"/}}
	284
48.2	285	== Creating new FAQ entries ==
1.1	286
80.1	287	There are 2 ways for you to let your users create new FAQ entries:
83.1	288
80.1	289	1. Declare the FAQ as a template
	290	1. Add a custom creation form
14.1	291
55.1	292	=== Using a Template ===
	293
83.1	294	You will have to define a template provider [[as explained on this page>>extensions:Extension.Administration Application\|\|anchor="HCreatethetemplateprovider"]]
55.1	295
80.1	296	Go to your wiki's administration interface, in the "Templates" section (Administration -> Content -> Templates). Create a new template provider in the "FAQ" space and name it "FAQTemplateProvider"
55.1	297
	298	You can then use the following values:
	299
	300	* Provider name: "FAQ Template Provider"
	301	* Template name "New FAQ entry"
60.8	302	* Template to use: "FAQ.FAQTemplate"
55.1	303
80.1	304	If you'd like, you can restrict FAQ entries so that they're created only in the "FAQ" space. Once you're done, click "Save & View". Your template is now ready to be used! Users who click on the "Add >> Page" button will now have the option to create a new page using the FAQ template.
55.1	305
	306	=== Custom creation form ===
	307
	308	If you choose this option, you will need to write some code to let your users create new FAQ entries. To do this, you will have to create a form in which the user can enter the name of the questions she wants to create. Once typed in, the form calls the same page to trigger the new document creation based on the parameters entered by the user:
	309
42.1	310	* The first part of the code checks whether the page has a parameter. If so:
	311	** The name of the document that will be created is computed
	312	** A check is done to verify the document doesn't exist yet
	313	** If everything's ok, the user is sent to the new document in inline edition mode
	314	* The second part of the code is the actual FAQ creation form
	315	** It builds the name of the document to create it in the "FAQ" space
	316	** It sets the document parent as being the current document
	317	** It defines the template to use to create the new document
1.1	318
48.1	319	{{code language="none"}}
42.1	320	{{velocity}}
	321	#if("$!request.docName" != '')
	322	## Request for creating a new instance
62.1	323	#set($docName = ${request.docName})
47.1	324	#set($targetDocName = "${request.spaceName}.${docName}")
62.1	325	#if(!$xwiki.exists($targetDocName) && $xwiki.hasAccessLevel('edit', $xcontext.user, $targetDocName))
61.1	326	$response.sendRedirect($xwiki.getURL($targetDocName, 'inline', "template=${escapetool.url($request.template)}&parent=${escapetool.url($request.parent)}"))
42.1	327	## Stop processing, since we already sent a redirect.
	328	#stop
	329	#end
	330	#end
1.1	331
42.1	332	= Add a new question =
	333
	334	#if("$!targetDocName" != '' && $xwiki.exists($targetDocName))
	335	{{warning}}The target document already exists. Please choose a different name, or [[view the existing document>>$targetDocName]]{{/warning}}
	336	#elseif("$!targetDocName" != '')
	337	{{warning}}You don't have permission to create that document{{/warning}}
	338	#end
	339
	340	{{html}}
	341	<form action="" id="newdoc" method="post">
	342	<div>
	343	<input type="hidden" name="parent" value="${doc.fullName}"/>
	344	<input type="hidden" name="template" value="FAQ.FAQTemplate"/>
	345	<input type="hidden" name="sheet" value="1"/>
	346	<input type="hidden" name="spaceName" value="FAQ"/>
	347	Document: <input type="text" name="docName" value="Enter your question here" class="withTip" size="50"/>
	348	<span class="buttonwrapper"><input type="submit" value="Create this FAQ" class="button"/></span>
	349	</div>
	350	</form>
	351	{{/html}}
	352	{{/velocity}}
48.1	353	{{/code}}
1.1	354
80.1	355	* Copy this code and paste it as Wiki content inside FAQ.WebHome, below the code that's already there
42.1	356	* Click "Save and View"
80.1	357	* A form to create new FAQ entries is now available on the page:(((
	358	{{image reference="FAQsWithForm.png"/}}
	359	)))
14.1	360
48.2	361	= Test the Application =
27.1	362
80.1	363	Now let's just create a new document in our application to test it out.
	364	If you previously chose to use a "Custom creation form" for creating new FAQ entries, follow these steps:
42.1	365
80.1	366	* Go to FAQ.WebHome
	367	* Below the "Add a new question" header, enter a question (which will also be used as the document title) in the //Document// field
	368	* Click //Create this FAQ//
52.1	369	* You can then enter your question in longer form using the //Question// field on the template, like this:(((
80.1	370	{{image reference="FAQSheetEdit.PNG"/}}
48.4	371	)))
52.1	372	* Click //Save & View// and then you will see the newly created document, like this:(((
80.1	373	{{image reference="FAQSheetView.PNG"/}}
48.4	374	)))
80.1	375	* Go back to the "FAQ.WebHome" page to see the list of existing questions(((
	376	{{image reference="FAQsWithEntry.png"/}}
	377	)))
42.1	378
48.2	379	= Conclusion =
1.1	380
80.1	381	This tutorial has taught you how to use the Class Wizard app and it has detailed the concepts of classes, objects and properties and introduced the authoring templates and page design sheets.
	382	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.
1.1	383
	384	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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