Tablestore:Highlight

Prerequisites

• An OTSClient instance is initialized. For more information, see Initialize an OTSClient instance.

• A data table is created and data is written to the data table. For more information, see Create data tables and Write data.

• A search index is created for the data table. For more information, see Create a search index.

Usage notes

• Tablestore SDK for Node.js V5.5.0 or later supports the highlight feature. Before you use the highlight feature, make sure that Tablestore SDK for Node.js V5.5.0 or later is obtained. For more information about the version history of Tablestore SDK for Node.js, see Version history of Tablestore SDK for Node.js.

• If you enable the highlight feature in a match query or match phrase query, the query strings in the query results may be highlighted by using multiple opening tags (preTag) and closing tags (postTag).

• If the tokenization method of a Text field is maximum semantic unit-based tokenization (MaxWord), the highlight feature is not supported when you perform a match phrase query on the Text field.

• If you want to return multiple fragments, the query strings in the fragments may be split. In this case, the query strings may not be highlighted.

Parameters

Examples

The following sample code provides an example on how to use the MatchQuery feature to query data that matches hangzhou shanghai from the Col_Text field and highlight the keywords in the query results. In this example, the Col_Text field is of the Text type.

client.search({
    tableName: "<TABLE_NAME>",
    indexName: "<SEARCH_INDEX_NAME>",
    searchQuery: {
        offset: 0,
        limit: 10, // To query only the number of rows that meet the query conditions without returning specific data, set the limit parameter to 0. 
        query: { // Set the query type to MatchQuery. 
            queryType: TableStore.QueryType.MATCH_QUERY,
            query: {
                fieldName: "Col_Text", // Specify the field that you want to match. 
                text: "hangzhou shanghai" // Specify the query string that you want to match. 
            }
        },
        highlight:{
            highlightEncoder:TableStore.HighlightEncoder.PLAIN_MODE,
            highlightParameters:[
                {
                    fieldName:"Col_Text",
                    preTag: "<b>",
                    postTag: "</b>",
                    fragmentsOrder: TableStore.HighlightFragmentOrder.TEXT_SEQUENCE,
                    fragmentSize: 20,
                    numberOfFragments: 3,
                }
                
            ],
        },
        getTotalCount: true // Specify whether to return the total number of rows that meet the query conditions. Default value: false. 
    },
    columnToGet: { // Specify the columns that you want to return. You can set the parameter to RETURN_SPECIFIED to return specific columns, RETURN_ALL to return all columns, RETURN_ALL_FROM_INDEX to return all columns in the search index, or RETURN_NONE to return only the primary key columns. 
        returnType: TableStore.ColumnReturnType.RETURN_ALL
    }
}, function (err, data) {
    if (err) {
        console.log('error:', err);
        return;
    }
    console.log('success:', JSON.stringify(data.rows, null, 2));
    printSearchHit(data.searchHits, "");
});


/**
 * Display the content that meets the query conditions. 
 * @param searchHits searchHits
 * If the output uses the @param prefix Nested structure, add the prefix to display the hierarchy information. 
 */
function printSearchHit(searchHits, prefix) {
    TableStore.util.arrayEach(searchHits, function (searchHit) {
        if (searchHit.highlightResultItem != null) {
            console.log(prefix + "Highlight: \n");
            var strBuilder = ""
            for  (const [key,val]  of searchHit.highlightResultItem.highlightFields.entries()) {
                strBuilder += key + ":[";
                strBuilder += val.fragments.join(",") + "]\n";
                console.log(strBuilder);
            }
        }
        for  (const [key,val]  of searchHit.searchInnerHits.entries()) {
            console.log(prefix + "Path: " + key + "\n");
            console.log(prefix + "InnerHit: \n");
            printSearchHit(val.subSearchHits, prefix + "    ");
        }
    });
}

References

• For information about the highlight feature, see Highlight.

• For information about how to use the highlight feature when you query nested fields, see Nested query.