Home > Articles

Exploring the Code

This chapter is from the book

This chapter is from the book

Search

The search system that is built into the starting point application is pretty simple. However, it does provide a foundation for a modular search system in which each module is responsible for providing a search service, but results are collated to provide a community-wide search. This means that as new modules are added, they can plug into the search system without the need to change the infrastructure code to include them.

Every module business service class includes a GetSearchResults(String) method. This is required by the ModuleBase base class from which they all inherit. This method returns a SearchResultCollection object. This is a custom collection that contains SearchResult objects.

Each SearchResult object has the following properties:

  • name (String)—A few words that describe the result

  • description (String)—A one-paragraph description

  • relevance (Single)—A number between 0 and 1 that indicates how relevant the search result is to the search terms

  • link (String)—The URL to which the user should be directed when she clicks on the search result

CoreModule, being derived from ModuleBase, also provides a GetSearchResults(String) method. It is ModuleBase.GetSearchResults that calls the SearchResults method for each installed module and collates the results.

The process for dealing with a search request is as follows:

  1. The user enters search terms in the search control.

  2. default.aspx is loaded, with the search URL parameter containing the search terms.

  3. A new SearchResults user control is created.

  4. The Results property of the control is set to the result of CoreModule.GetSearchResults.

  5. CoreModule.GetSearchResults calls GetSearchResults for each installed module, passing the search terms.

  6. Each module returns its search results.

  7. CoreModule.GetSearchResults collates the results and returns them.

  8. The results are displayed in the SearchResults control.

Each module can create its own set of search results in any way we like, so each module can work in the way that makes sense for its content.

Let's take a look at the GetSearchResults method for the News module. Open Modules/News/NewsModule.vb and find the method:

Public Overrides Function GetSearchResults(ByVal pSearchTerms As String) _
         As SearchResultCollection
 Dim results As New SearchResultCollection


 Dim crit1 As New Criteria


 crit1.AddLike("_Body", "%" & pSearchTerms & "%")

 Dim crit2 As New Criteria

 crit2.AddLike("_Title", "%" & pSearchTerms & "%")

 Dim crit3 As New Criteria
 crit3.AddLike("_Summary", "%" & pSearchTerms & "%")

 crit1.AddOrCriteria(crit2)

 crit1.AddOrCriteria(crit3)

 Dim crit4 As New Criteria

 crit4.AddEqualTo("_ModuleInstanceID", Me.ModuleInstance.PrimaryKey1)

 crit1.AddAndCriteria(crit4)

 Dim newsItems As IList =
QueryFacade.Find(Type.GetType("Community.NewsItem"), crit1) Dim ni As NewsItem For Each ni In newsItems results.add(New SearchResult(ni.Title, ni.Summary, 0.5, "default.aspx?Module=1&Item=" & ni.PrimaryKey1,
ni.ModuleInstance)) Next Return results End Function

First, we create a SearchResultCollection object. This is a custom collection class we will look at shortly.

We build a Criteria tree that will return a result if the search terms are found in the title, summary, or body of the news item. We also include a Criteria to require that the item is from the instance that is currently performing the search.

We then retrieve the items and create a SearchResult object for each of them in turn before returning the complete set of results.

The SearchResult class is a simple class, not a persistent object. We don't need to save SearchResult objects to the database, so they do not need to interact with the persistence service.

You can find the SearchResult class in Global/Search/SearchResult.vb. It is a simple combination of fields and properties to carry the data about the search result.

SearchResultCollection, found in Global/Search/SearchResultCollection.vb, is more complicated. Open that file now to take a look at it.

There are actually two classes in this file. To work properly, a custom collection class needs a matching custom enumerator class. Because they are so closely linked, we have put them in the same file.

The enumerator is important because, by providing an enumerator, our collection class can be used just like the standard collections. We can, therefore, use For Each loops and other standard looping techniques to access the members. The enumerator does the job of looping through the members of the collection.

Let's start at the top with SearchResultEnumerator.

It starts by stating that the class will implement the IEnumerator interface:

Public Class SearchResultEnumerator
 Implements IEnumerator

It is this interface that enables our custom enumerator to be treated as an enumerator by outside code. (We will see why this is important shortly.)

Next come the private fields:

Private _index As Integer = -1
Private _searchResultCollection As SearchResultCollection

We store the current index and the SearchResultCollection object to which the enumerator is attached.

Next, we provide a method to reset the enumerator back to the beginning of the collection:

Public Sub reset() Implements IEnumerator.Reset
 _index = -1
End Sub

In fact, we have to implement this method. As shown by the inclusion of the Implements statement, it is one of the methods that IEnumerator requires us to include.

IEnumerator also requires us to provide a method that returns the item to which the enumerator is currently pointing:

Public ReadOnly Property Current() As Object Implements
IEnumerator.Current Get If _index > -1 Then Return _searchResultCollection(_index) Else Return -1 End If End Get End Property

We check whether the current index is above –1. If it is, we return the relevant item from the collection. If it is not, we cannot return an item because the enumerator has not yet started enumerating the collection. We return -1 instead.

The final method we have to implement moves the enumerator to the next item in the collection:

Public Function MoveNext() As Boolean Implements IEnumerator.MoveNext
 _index = _index + 1
 If _index < _searchResultCollection.count Then
  Return True
 Else
  Return False
 End If
End Function

We move the index on and then check that we have not moved outside of the size of the collection. If we have, we return False to let the calling code know that the end of the collection has been reached.

So, we have seen the enumerator. Let's now look at the collection it enumerates.

We start by implementing the IEnumerable interface:

Public Class SearchResultCollection
 Implements IEnumerable

This is the key to a custom collection class—by implementing this interface, the calling code knows that it can get an enumerator to perform For Each loops and so on.

Then, we have a private field to hold the actual results:

Private results As ArrayList = New ArrayList

We provide a this property that will enable members of the collection to be accessed by their index:

Default Public Property this(ByVal index As Integer) As SearchResult
 Get
  Return CType(results(index), SearchResult)
 End Get
 Set(ByVal Value As SearchResult)
  results(index) = Value
 End Set
End Property

By including this property with the specific name this, we allow calling code to use standard indexed access syntax to access the members.

Then, we have a method to add items to the collection and a property to get the current length of the collection:

Public Sub add(ByVal item As SearchResult)
 results.Add(item)
End Sub


Public ReadOnly Property count() As Integer
 Get
  Return results.Count
 End Get
End Property

Finally, we have a method, required by IEnumerable, to get an enumerator for the collection:

Public Function GetEnumerator() As IEnumerator Implements
  IEnumerable.GetEnumerator
 Return New SearchResultEnumerator(Me)
End Function

You might be wondering what the point of using a custom collection class is, as opposed to simply putting the search results into an ArrayList or similar.

By using our custom class, we guarantee that only SearchResult objects can be added to the collection (because the add method will only accept SearchResult objects) and we also get the opportunity to include custom logic if we want to. For example, we might decide to have the SearchResultCollection automatically sort the search results by priority. We might be able to do that more efficiently within the collection, as items are added, than calling code would be able to.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.

Overview


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information


To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.

Surveys

Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.

Newsletters

If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information


Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.

Security


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.

Children


This site is not directed to children under the age of 13.

Marketing


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information


If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.

Choice/Opt-out


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information


Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents


California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure


Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.

Links


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact


Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice


We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020