Add highlighting to a custom search type

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Solr's highlighting feature lets you include fragments in the highlighting section of a query response.

You can add highlights to a custom search type by first enabling highlighting on a specific field, then adding the Highlights type property to the custom search type.

To add highlights:

In the <SOLR_DIR>\server\solr\<SOLR_CORE_NAME>\conf folder, in the managed-schema file, enable highlighting for the desired fields by setting the stored property of the fields to true, as shown in the following example:

<field name="title_t" type="text_general" multiValued="true" indexed="true" stored="true"/>
<field name="text" type="text_general" multiValued="true" indexed="true" stored="true"/>

Create a custom search type class and add public properties that return the Highlights type, then map each property to its appropriate index field, as shown in the following example:

public class SimpleHighlightResultItem
    {
       [IgnoreIndexField]
       public string Title { get; set; }
    
       [IndexField("title")]
       public Highlights HighlightsInTitle { get; set; }
    
       [IgnoreIndexField]
       public string Text { get; set; }
    
       [IndexField("text")]
       public Highlights HighlightsInText { get; set; }
    }

Use the custom search type in a LINQ query. For example:

var index = ContentSearchManager.GetIndex("sitecore_master_index");
    
    using (var context = index.CreateSearchContext())
    {
        var result = context.GetQueryable<SimpleHighlightResultItem>()
            .Where(it => it.Title == "Sitecore" && it.Text == "customer experience")
            .WithHighlights(hl => hl.HighlightOn(i => i.HighlightsInText));
        
        foreach (var resultItem in result)
        {
            string[] highlightSegments = resultItem.HighlightsInText.ToArray();
        }
    }

The preceding LINQ query generates the following Solr query: q=(title_t:("Sitecore") AND text:("customer experience")) ... &hl=true&hl.fl=text

The highlightSegments property contains the following segment:

" complexity that has previously held marketers back, the latest version of <em>Sitecore</em> makes <em>customer</em> <em>experience</em>"

Highlight multiple fields in a LINQ query

You can get highlighted matches for several index fields in a single LINQ query.

The following query returns highlights for both the title and text index fields:

var result = context.GetQueryable<SimpleHighlightResultItem>()
        .Where(it => it.Title == "Sitecore" && it.Text == "customer experience")
        .WithHighlights(hl => hl
            .HighlightOn(i => i.HighlightsInText)
            .HighlightOn(i => i.HighlightsInTitle)
        )
        .ToArray();

The preceding LINQ query generates the following Solr query: q=(title_t:("Sitecore") AND text:("customer experience")) ... &hl=true&hl.fl=title_t,text

The HighlightsInText property contains the following segment:

" complexity that has previously held marketers back, the latest version of <em>Sitecore</em> makes <em>customer</em> <em>experience</em>"

The HighlightsInTitle property contains the following segment:

"<em>Sitecore<em> Experience Platform"

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