Search Application Client

The Search Application Client is a JavaScript library that provides functionality for interacting with a search application in Elasticsearch.

ℹ️ The Search Application Client is in technical preview and is subject to change.

Quick Access

Here are some quick links to the important sections:

• Installation
• Usage
• API Reference
• Advanced Usage
• Examples

Installation

To install the Search Application Client, you can use npm or yarn.

Using npm:

npm install @elastic/search-application-client

Using yarn:

yarn add @elastic/search-application-client

In Browser via CDN

<script src="https://cdn.jsdelivr.net/npm/@elastic/search-application-client@latest"></script>

Usage

Importing the Client

You can import the Search Application Client in your JavaScript or TypeScript file using the following import statement:

import SearchApplicationClient from '@elastic/search-application-client';

Creating an Instance of Client

To use the Search Application Client, create an instance by calling the function returned by the imported module:

const client = SearchApplicationClient(applicationName, endpoint, apiKey, params);

• applicationName: The name of the search application.
• endpoint: The URL of the search application's endpoint.
• apiKey: The API key for accessing the search application.
• params (optional): Additional parameters to be passed to the client.
• apiOptions (optional): Additional options to be passed to the API client.
  • cacheExpiration (optional): The cache expiration time in milliseconds. Default: 3600000 (one hour).
  • cache (optional): Enable/disables the cache. Default: true.
  • headers (optional): Additional headers to be passed to the API client.
• Returns: A function that returns a new QueryBuilder instance.

Using the Client

The Search Application Client provides a QueryBuilder class that allows you to build complex search queries:

const results = await client()
  .query('John')
  .search()

The search method returns a Promise that resolves with the search results.

Use facets

To use facets filtering, specify facets in the client initialization:

const client = SearchApplicationClient('*search-application-name*', '*elasticsearch-endpoint*', '*apiKey*', {
  facets: {
    category: { type: 'terms', field: 'category.keyword', size: 10 },
    price: { type: 'stats', field: 'price', size: 10, disjunctive: true },
  },
});

const results = await client()
  .addFacetFilter('category', 'electronics')
  .addFacetFilter('price', { from: 100, to: 1000 })
  .addFacetFilter('author', 'orwell') // ❌ Throw an error, because the facet is not specified during initialization
  .setSort({'price': 'desc'})
  .search()

Use sorting

To use sorting, specify the field name and the sort order or pass _score to sort by relevance:

const results = await client()
  .setSort([{'publish_date': 'desc'}, "_score"])
  .search()

Use pagination

To use pagination, set the page number and the page size:

const results = await client()
  .setPageSize(20)
  .setFrom(20 * 2) // For the third page
  .search()

By default, page size is 10

Use additional parameters

const results = await client()
  .addParameter('custom-parameter', 'custom-value')
  .search()

API Reference

SearchApplicationClient()

Function to initialize searchApplicationClient and returns function to create an instance of the QueryBuilder.

• applicationName (string): The name of the search application.
• endpoint (string): The URL of the search application's endpoint.
• apiKey (string): The API key for accessing the search application.
• params? (Params): Additional parameters to be passed to the client.

Returns: function that returns new QueryBuilder instance.

QueryBuilder

This class provides methods for building search queries.

• query(query: string): QueryBuilder Sets the search query. Returns: QueryBuilder instance.

• addFacetFilter(field: string, value: FilterFieldValue): QueryBuilder Adds a facet filter to narrow down the search results. Returns: QueryBuilder instance.

  • field (string): The field name of the facet filter.
  • value (string | string[] | number | number[]): The value or range of values for the facet filter.

• addParameter(field: string, value: unkown): QueryBuilder Adds a parameter to the query. Returns: QueryBuilder instance.

• setPageSize(size: number): QueryBuilder Sets the size for maximum number of results to return. Returns: QueryBuilder instance.

• setFrom(value: number): QueryBuilder Defines the number of results to skip, defaulting to 0. Returns: QueryBuilder instance.

• setSort(sort: SortFields): QueryBuilder Sets the sorting criteria for the search results. Returns: QueryBuilder instance.

  • sort (Record<string, 'desc' | 'asc'> | '_score')[]): The sorting criteria for the search results.

• search(): Promise<ResponseParams> Sends the search request to the search application. Use generic types for specify hits._source type. Returns: A promise that resolves to the search results.

  • hits: An array of search hits.
  • facets: An array of facet results.
  • aggregations: An object containing aggregation results.
  • total: The total number of search results.
  • took: The time taken for the search request.

Please refer to the code and type definitions for more details on the available methods and their parameters.

Advanced Usage

Boilerplate template

PUT _application/search_application/example-app
{
  "indices": ["example-index"],
  "template": {
    "script": {
      "lang": "mustache",
      "source": """
        {
          "query": {
            "bool": {
              "must": [
              {{#query}}
              {
                "query_string": {
                  "query": "{{query}}"
                }
              }
              {{/query}}
            ],
            "filter": {{#toJson}}_es_filters{{/toJson}}
            }
          },
          "aggs": {{#toJson}}_es_aggs{{/toJson}},
          "from": {{from}},
          "size": {{size}},
          "sort": {{#toJson}}_es_sort_fields{{/toJson}}
        }
      """,
      "params": {
        "query": "",
        "_es_filters": {},
        "_es_aggs": {},
        "_es_sort_fields": {},
        "size": 10,
        "from": 0
      }
    }
  }
}

Using custom template

To use custom template you can update boilerplate template within specific properties or params like highlight property:

PUT _application/search_application/example-app
{
  "indices": ["example-index"],
  "template": {
    "script": {
      "lang": "mustache",
      "source": """
        {
          "query": {
            "bool": {
              "must": [
              {{#query}}
                // ...
              {{/query}}
            ],
            "filter": {{#toJson}}_es_filters{{/toJson}}
            }
          },
          "_source": {
            "includes": ["title", "plot"]
          },
          "highlight": {
    		"fields": {
      		  "title": { "fragment_size": 0 },
                "plot": { "fragment_size": 200 }
             }
          },
          "aggs": {{#toJson}}_es_aggs{{/toJson}},
          "from": {{from}},
          "size": {{size}},
          "sort": {{#toJson}}_es_sort_fields{{/toJson}}
        }
      """,
      "params": {
        "query": "",
        "_es_filters": {},
        "_es_aggs": {},
        "_es_sort_fields": {},
        "size": 10,
        "from": 0
      }
    }
  }
}

Using dictionary for template

To use template with typechecking you can update your template with prebuilded json schema by running command:

npx @elastic/search-application-client update-template

Once you have updated the template it will use the schema for typechecking of params for each request.

Examples

You can find usage examples in the examples/sandbox directory of this repository. These examples demonstrate how to use the search-application-client library.