Setting analyzers for Azure Search

Azure Search uses Language analyzers to process text values. By default, searchable fields are analyzed with the Apache Lucene Standard analyzer. Because Azure Search supports a variety of languages, it additionally provides other text analyzers with more advanced capabilities for specific languages.

If you wish to assign a specific analyzer to the fields of an index, customize the functionality that Kentico uses to build Azure Search indexes:

  1. Open your Kentico solution in Visual Studio.
  2. Create a custom module class.
  3. Override the module's OnInit method and assign a handler to the DocumentFieldCreator.Instance.CreatingField.After event.
  4. Perform the following in the event's handler method:

    1. Write a condition to limit which search indexes and fields are affected by the analyzer customization (using values of the SearchIndex and SearchField properties of the handler's CreateFieldEventArgs parameter).
    2. Access the Field property of the handler's CreateFieldEventArgs parameter, and assign a valid analyzer name into one of its Analyzer properties.

      Field analyzer properties

      The Field class (Microsoft.Azure.Search.Models.Field) offers the following properties for setting the analyzer:

      • Analyzer
      • IndexAnalyzer (used at indexing time)
      • SearchAnalyzer (used at search time)

      For more information, see the Index Attributes section of the Create Index article.

  5. Sign in to the Kentico administration interface.
  6. Open the Smart search application and Rebuild any related Azure Search indexes.

The customized Azure Search index fields now use the specified language analyzer.

Example

The following example demonstrates how to set the language analyzer for the skudescription field of an Azure Search index named dg-store.

Start by preparing a separate project in your Kentico solution for the custom module class:

  1. Open your Kentico solution in Visual Studio.
  2. Create a new Class Library project in the Kentico solution named SearchCustomization.
  3. Add references to the required Kentico libraries (DLLs) for the new project:
    1. Right-click the project and select Add -> Reference.
    2. Switch to the Browse tab, click Browse, and navigate to the Lib folder of your Kentico web project.
    3. Add references to the following libraries:

      • CMS.Base.dll
      • CMS.Core.dll
      • CMS.DataEngine.dll
      • CMS.Search.Azure.dll
  4. Right-click the SearchCustomization project in the Solution Explorer and select Manage NuGet Packages.
  5. Install the Microsoft.Azure.Search package.
  6. Reference the SearchCustomization project from the Kentico web project (CMSApp or CMS).
  7. Edit the SearchCustomization project's AssemblyInfo.cs file (in the Properties folder). 

  8. Add the AssemblyDiscoverable assembly attribute:

    using CMS;
    
    [assembly:AssemblyDiscoverable]

Continue by implementing the custom module class and rebuilding the related search index:

  1. Create a new class named CustomAzureSearchModule under the SearchCustomization project, with the following code:

    using System;
    
    using CMS;
    using CMS.DataEngine;
    using CMS.Search.Azure;
    
    // Registers the custom module into the system
    [assembly: RegisterModule(typeof(CustomAzureSearchModule))]
    
    public class CustomAzureSearchModule : Module
    {
        // Module class constructor, the system registers the module under the name "CustomAzureSearch"
        public CustomAzureSearchModule()
            : base("CustomAzureSearch")
        {
        }
    
        // Contains initialization code that is executed when the application starts
        protected override void OnInit()
        {
            base.OnInit();
    
            // Assigns a handler to the CreatingField.After event for Azure Search indexes
            DocumentFieldCreator.Instance.CreatingField.After += UseCustomSearchAnalyzer;
        }
    
        private void UseCustomSearchAnalyzer(object sender, CreateFieldEventArgs e)
        {
            string indexName = e.SearchIndex.IndexCodeName;
            string fieldName = e.SearchField.FieldName;
    
            // Sets the 'en.microsoft' analyzer for the 'skudescription' field in the 'dg-store' index
            if (indexName.Equals("dg-store", StringComparison.InvariantCultureIgnoreCase)
                && fieldName.Equals("skudescription", StringComparison.InvariantCultureIgnoreCase))
            {
                e.Field.Analyzer = "en.microsoft";
            }
        }
    }
  2. Save all changes and Build the SearchCustomization project.
  3. Sign in to the Kentico administration interface.
  4. Open the Smart search application and Rebuild the dg-store index.

The skudescription field of the dg-store index now uses the "en.microsoft" language analyzer, both during indexing and at search time.


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