Creating custom smart search indexes

When creating custom smart search indexes, you do not define the content on the Indexed content tab in the Smart search application. Instead, you must implement all functionality of the index in code. In the administration interface, you only need to specify the names of the assembly and class that contain the custom index logic.

To define a custom index, create a class that implements the ICustomSearchIndex interface (CMS.Search namespace).

To integrate the class into your application, create a new assembly (Class Library project) containing the index class and include the assembly in your web project.

Defining custom indexes for MVC sites

If you are utilizing the MVC development model, consider whether you also need to deploy the custom assembly to your MVC application. This is necessary if you want your custom index to perform content updates based on actions that occur on the live site.

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Writing the custom index code

The following example shows how to create a custom index that searches the content of text files:

  1. Open your Kentico solution in Visual Studio.
  2. Create a new Class Library project in the Kentico solution (or reuse an existing custom project). For example, name the project CustomSearch.
  3. Add references to the required Kentico libraries (DLLs) for the new project:
    1. Right-click the project and select Add -> Reference.
    2. Select the Browse tab of the Reference manager dialog, click Browse and navigate to the Lib folder of your Kentico project.
    3. Add references to the following libraries (and any others that you may need in your custom code):
      • CMS.Base.dll
      • CMS.Core.dll
      • CMS.DataEngine.dll
      • CMS.EventLog.dll
      • CMS.Helpers.dll
      • CMS.IO.dll
      • CMS.Search.dll
  4. Reference the custom project from the Kentico web project (CMSApp or CMS).
  5. Add a new class into the custom project. For example, name the class TextFileIndex.cs.
  6. Edit the class and make sure that the following using statements are present at the top of the code:

    using System;
    
    using CMS.Base;
    using CMS.DataEngine;
    using CMS.EventLog;
    using CMS.Helpers;
    using CMS.IO;
    using CMS.Search;
    
  7. Make the class implement the ICustomSearchIndex interface.

    public class TextFileIndex : ICustomSearchIndex
  8. Define the Rebuild method inside the class:

    You must always include the Rebuild method when writing custom indexes. The method fills the index with data, which determines what kind of searches the index provides. The system calls the method when building the index for the first time and on each subsequent rebuild.

    /// <summary>
    /// Fills the index with content.
    /// </summary>
    /// <param name="srchInfo">Info object representing the search index</param>
    public void Rebuild(SearchIndexInfo srchInfo)
    {
    	// Checks whether the index info object is defined
    	if (srchInfo != null)
    	{
    		// Gets an index writer object for the current index
    		IIndexWriter iw = srchInfo.Provider.GetWriter(true);
    
    		// Checks whether the writer is defined
    		if (iw != null)
    		{
    			try
    			{
    				// Gets an info object of the index settings
    				SearchIndexSettingsInfo sisi = srchInfo.IndexSettings.Items[SearchHelper.CUSTOM_INDEX_DATA];
    
    				// Gets the search path from the Index data field
    				string path = Convert.ToString(sisi.GetValue("CustomData"));
    
    				// Checks whether the path is defined
    				if (!String.IsNullOrEmpty(path))
    				{
    					// Gets all text files from the specified directory
    					string[] files = Directory.GetFiles(path, "*.txt");
    
    					// Loops through all files
    					foreach (string file in files)
    					{
    						// Gets the current file info
    						FileInfo fi = FileInfo.New(file);
    
    						// Gets the text content of the current file
    						string text = fi.OpenText().ReadToEnd();
    						
    						// Checks that the file is not empty
    						if (!String.IsNullOrEmpty(text))
    						{
    							// Converts the text to lower case
    							text = text.ToLowerCSafe();
    
    							// Removes diacritics
    							text = TextHelper.RemoveDiacritics(text);
    
    							// Creates a new Lucene.Net search document for the current text file
    							SearchDocumentParameters documentParameters = new SearchDocumentParameters()
    							{
    								Index = srchInfo,
    								Type = SearchHelper.CUSTOM_SEARCH_INDEX,
    								Id = Guid.NewGuid().ToString(),
    								Created = fi.CreationTime
    							};
    							ILuceneSearchDocument doc = LuceneSearchDocumentHelper.ToLuceneSearchDocument(SearchHelper.CreateDocument(documentParameters));
    
    							// Adds a content field. This field is processed when the search looks for matching results.
    							doc.AddGeneralField(SearchFieldsConstants.CONTENT, text, SearchHelper.StoreContentField, true);
    
    							// Adds a title field. The value of this field is used for the search result title.
    							doc.AddGeneralField(SearchFieldsConstants.CUSTOM_TITLE, fi.Name, true, false);
    
    							// Adds a content field. The value of this field is used for the search result excerpt.
    							doc.AddGeneralField(SearchFieldsConstants.CUSTOM_CONTENT, TextHelper.LimitLength(text, 200), true, false);
    
    							// Adds a date field. The value of this field is used for the date in the search results.
    							doc.AddGeneralField(SearchFieldsConstants.CUSTOM_DATE, fi.CreationTime, true, false);
    
    							// Adds a url field. The value of this field is used for link urls in the search results.
    							doc.AddGeneralField(SearchFieldsConstants.CUSTOM_URL, file, true, false);
    
    							// Adds an image field. The value of this field is used for the images in the search results.
    							// Commented out, since the image file does not exist by default
    							// doc.AddGeneralField(SearchFieldsConstants.CUSTOM_IMAGEURL, "textfile.jpg", true, false);
    
    							// Adds the document to the index
    							iw.AddDocument(doc);
    						}
    					}
    
    					// Flushes the index buffer
    					iw.Flush();
    
    					// Optimizes the index
    					iw.Optimize();
    				}
    			}
    
    			// Logs any potential exceptions
    			catch (Exception ex)
    			{
    				EventLogProvider.LogException("CustomTextFileIndex", "Rebuild", ex);
    			}
    
    			// Always close the index writer
    			finally
    			{
    				iw.Close();
    			}
    		}
    	}
    }
  9. Rebuild the solution.

You need to write the code of the Rebuild method according to the specific purpose of the index. Use the following general steps for all indexes:

    1. Get an Index writer instance for the search index.
      • The index writer object must implement the CMS.Search.IIndexWriter interface.
      • Get the index writer by calling the Provider.GetWriter(true) method of the SearchIndexInfo object.
    2. Define search Documents and their fields for the items that you wish to add to the index.
      • Custom search document objects must implement the CMS.Search.ILuceneSearchDocument interface.
      • Create search documents by calling the CMS.Search.SearchHelper.CreateDocument method, and then convert the result via the LuceneSearchDocumentHelper.ToLuceneSearchDocument method.
    3. Call the AddDocument method of the Index writer for every search document.
    4. After you have added all required search documents, call the Flush and Optimize methods of the Index writer.
    5. Call the Close method of the Index writer.

Using data parameters for custom indexes

The SearchIndexInfo parameter of the Rebuild method allows you to access the data fields of the corresponding search index object. The sample code loads the content of the Index data field and uses it to define the path to the searched text files.

When writing your own custom indexes, you can use the Index data field as a string parameter for any required purpose. The parameter allows you to modify the behavior of the index directly from the administration interface without having to edit the index code.

Updating the content of custom indexes

By default, the only way to update the content of a custom index is to rebuild the whole index (i.e. using the implementation of the Rebuild method). You cannot use the Kentico search indexing tasks to update custom indexes.

With additional custom development, you can update indexes by calling the Update or Delete methods of the CMS.Search.SearchHelper class. Typically, you need to update the index from custom code outside of the index class whenever the indexed content changes. However, in this case you need to ensure that the API is never called concurrently – problems can occur if multiple processes attempt to update the same index at the same time.

Registering custom search indexes

  1. Sign in to the Kentico administration interface and open the Smart search application.
  2. Select the Local indexes tab.
  3. Click New Index. Fill in the following properties:
    • Display name: Text file index
    • Index type: Custom Index
  4. Click Save.
  5. Switch to the Indexed content tab and enter the names of the assembly and class where the custom index is implemented:
    • Assembly name: CustomSearch (the name of your custom assembly)
    • Class: CustomSearch.TextFileIndex (the name of the index class, including its namespace)
  6. Type any required parameters into the Index data field. In this example, you need to specify the file system path of the folder containing the text files that the index will search. You can create a new folder for this purpose, e.g. C:\SearchExample\ and add some text files into it.
  7. Click Save.
  8. Go to the General tab and Rebuild the index.

Result

The index is now fully functional. To test the index, switch to the Search preview tab and try searching for any words from the text files created in the SearchExample folder.


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