elastic_app_search 0.5.0

Dart/Flutter package for using Elastic App Search through a simple API returning easy to handle objects

Dart/Flutter package for using Elastic App Search through a simple API returning easy to handle objects

This package is a ready-to-use API for Elastic App Search.

⚠️ You need an active deployment on Elastic to use this service.

This package does not intend to learn you how Elastic App Search is working, it is just intended to help you make queries and manipulate results easily, assuming that you already know Elastic App Search principles.

Here is a simple example of how you can query your Elastic engine:

final service = ElasticAppSearch(
  endPoint: "https://host-2376rb.api.swiftype.com",
  searchKey: "search-371auk61r2bwqtdzocdgutmg",
);

ElasticResponse response = await service
  .engine("search-ui-examples")
  .query("mountains")
  .filter("states", isEqualTo: "California")
  .filter("world_heritage_site", isEqualTo: true)
  .resultField("title")
  .resultField("description", snippetSize: 140)
  .page(1, size: 50)
  .get();

for (ElasticResult result in response.results) {
  final data = result.data;
  if (data != null) {
    print("${data["title"]}: ${data["description"]}");
  }
}

This example will query the parks containing parks in any field of the documents. The results will be filtering the parks based in California, with the flag world_heritage_site set to true. Only the title and a snippet of 140 chars of the description of the park will be returned by the query. We request the first page, limited to 50 documents.

A full use case is available in the example folder, with the following rendering:

• The search bar makes dynamic queries to Elastic
• The popup menu allows you to filter parks if they are World Heritage or not

Table of contents

• ElasticAppSearch
• ElasticEngine
• ElasticQuery
  • Precision
  • Search filters
  • Search fields
  • Result fields
  • Facets
  • Disjunctive facets
• ElasticSuggestionQuery
• ElasticResponse
  • ElasticResponseMeta
    • ElasticResponseMetaPage
  • ElasticResult
    • ElasticResultMeta
    • ElasticResultSnippet

ElasticAppSearch

Before any operation, you need to create an instance of ElasticAppSearch.

Param	Type	Description
endPoint	String	The URL of your end point
searchKey	String	The search key of your deployment

Both values are available in your deployment, when going to App Search then Credentials. Warning: use the search-key, not the private-key!

final service = ElasticAppSearch(
    endPoint: "https://localhost:5601", 
    searchKey: "search-soaewu2ye6uc45dr8mcd54v8",
);

ElasticEngine

All the queries must be sent to an engine. To make instantiating an engine easy, we created this syntax:

Type	Description
String	The name of your engine

final engine = service.engine("engine_name");

ElasticQuery

The only required parameter to instanciate a query is a string which is the word you are looking for through your documents.

🔍 See https://www.elastic.co/guide/en/app-search/current/search.html

Type	Description
String	The keyword

final query = engine.query("query");

Precision

This setting is available through the query modifier .precision

The value of the precision parameter must be an integer between 1 and 11, inclusive. The range of values represents a sliding scale that manages the inherent tradeoff between precision and recall. Lower values favor recall, while higher values favor precision.

🔍 See https://www.elastic.co/guide/en/app-search/current/search-api-precision.html

final query = query.precision(5);

Search filters

This setting is available through the query modifier .filter

This feature intends to filter documents that contain a specific field value. It's only available on text, number, and date fields.

There are three types of filters:

• all: All of the filters must match. This functions as an AND condition. To add a filter to "all" filters, .filter.
• any: At least one of the filters must match. This functions as an OR condition. To add a filter to "any" filters, use .filterAny.
• none: All of the filters must not match. This functions as a NOT condition. To add a filter to "none" filters, use .filterNone.

🔍 See https://www.elastic.co/guide/en/app-search/current/filters.html

Param	Type	Description
(unnamed)	String	The field name
isEqualTo	dynamic (optionnal)	The value that the field must match
whereIn	List<dynamic> (optionnal)	The field must match one of these values
isGreaterThanOrEqualTo	DateTime or double (optionnal)	Inclusive lower bound of the range
isLessThan	DateTime or double (optionnal)	Exclusive upper bound of the range
isFurtherThanOrAt	double (optionnal)	Inclusive lower bound of the range
isLessFarThan	double (optionnal)	Exclusive upper bound of the range
from	LatLong (optionnal)	The base point from which distance params will be applied
unit	GeoUnit (optionnal)	The base unit of measurement

final query = query.filter("field", isEqualTo: "value");

final query = query.filter("field", isEqualTo: true);

final query = query.filter("field", whereIn: ["value1", "value2"]);

final query = query.filter("field", isGreaterThanOrEqualTo: 50, isLessThan: 100);

final query = query.filter("field", 
  isFurtherThanOrAt: 50, 
  unit: GeoUnit.miles, 
  from: LatLong(37.7749, -122.4194)
);

Search fields

This setting is available through the query modifier .searchField

It will restrict a query to search only specific fields. Restricting fields will result in faster queries, especially for schemas with many text fields Only available within text fields.

Weight is given between 10 (most relevant) to 1 (least relevant).

🔍 See https://www.elastic.co/guide/en/app-search/current/search-fields-weights.html

Param	Type	Description
(unnamed)	String	The field name
weight	int (optionnal)	The weight of the field in the query

final query = query
  .searchField("field1", weight: 8)
  .searchField("field2", weight: 3);

Result fields

This setting is available through the query modifier .resultField

The fields which appear in search results and how their values are rendered.

Raw is an exact representation of the value within a field. Snippet is a representation of the value within a field, where query matches are returned in a specific field and other parts are splitted, in order to user [RichText] to display the results and highlight the query matches.

🔍 See https://www.elastic.co/guide/en/app-search/current/result-fields-highlights.html

Param	Type	Description
(unnamed)	String	The field name
rawSize	int (optionnal)	The length of the field value which is returned
snippetSize	int (optionnal)	The length of the snippet value which is returned
fallback	bool (optionnal)	If true, return the raw text field if no snippet is found. If false, only use snippets.

final query = query
  .resultField("field1", rawSize: 80)
  .resultField("field2", snippetSize: 80)
  .resultField("field3", rawSize: 80, snippetSize: 80, fallback: true);

Facets

This setting is available through the query modifier .facet

Provides the counts of each value (or each range of value if you provide a range) for a field.

🔍 See https://www.elastic.co/guide/en/app-search/current/facets.html

Param	Type	Description
(unnamed)	String	The field name
name	String (optionnal)	Name given to facet.
isMoreThanOrEqualTo	DateTime or double (optionnal)	Inclusive lower bound of the range.
isLessThan	DateTime or double (optionnal)	Exclusive upper bound of the range.
isFurtherThanOrAt	double (optionnal)	Inclusive lower bound of the range
isLessFarThan	double (optionnal)	Exclusive upper bound of the range
from	LatLong (optionnal)	The base point from which distance params will be applied
unit	GeoUnit (optionnal)	The base unit of measurement

final query = query
  .facet("dateField",
    isLessThan: DateTime.utc(1984),
    name: "Before 1984",
  )
  .facet("dateField",
    isMoreThanOrEqualTo: DateTime.utc(1984),
    isLessThan: DateTime.utc(2014),
    name: "From 1984 to 2014",
  )
  .facet("dateField",
    isMoreThanOrEqualTo: DateTime.utc(2014),
    name: "Since 2014",
  );

Disjunctive facets

Disjunctive facets are useful when you have many filters in your form, and especially when you filter your query with a value that corresponds to a facet: if a disjunctive facet is set, it will return all the available facets as if that filter was not applied.

final query = query.disjunctiveFacet("field");

ElasticSuggestionQuery

The only parameter required to instantiate a query suggestion is a string that is the word for which you want to get query suggestions.

🔍 See https://www.elastic.co/guide/en/app-search/current/query-suggestions-guide.html

Type	Description
String	The keyword

final suggestionQuery = engine.suggestionQuery("query");

Configuration	Type	Description
size	int	Limits the number of results
searchFields	List<ElasticSearchField>	See Search fields
sortBy	List<ElasticSort>	Allows you to add one or more sorts on specific fields. See https://www.elastic.co/guide/en/elasticsearch/reference/current/sort-search-results.html

ElasticResponse

The response object contains two parts, the meta in a ElasticResponseMeta object and the results in a list of ElasticResult objects.

🔍 See https://www.elastic.co/guide/en/app-search/current/search.html#search-api-response-body

Param	Type	Description
meta	ElasticResponseMeta	Object delimiting the results meta data
results	List<ElasticResult>	Array of results matching the search

ElasticResponseMeta

An object containing information about the results, especially the pagination details in page.

Param	Type	Description
requestId	String	ID representing the request. Guaranteed to be unique
warnings	List<dynamic>	Array of warnings for the query
alerts	List<dynamic>	Array of alerts for your deployment
page	ElasticMetaPage	Object delimiting the pagination meta data

ElasticResponseMetaPage

Object delimiting the results meta data.

Param	Type	Description
current	int	Number representing the current page of results
size	int	Number representing the results per page
totalPages	int	Number representing the total pages of results
totalResults	int	Number representing the total results across all pages

ElasticResult

An object presenting a result to the query.

The data param is a map of the fields requested with the .searchResult modfifier. If this modifier was omitted, all the fields of the document are returned.

The snippets is a map of the snippets returned by the query, if requested with the .searchResult modfifier. By default, Elastic returns the snippets as HTML snippets. This package manipulates the result to return some stuff that can be handled by Flutter: an ElasticResultSnippet object.

Param	Type	Description
data	Map<String, dynamic>	A map of the raw data of the document
snippets	Map<String, ElasticResultSnippet>	A map of the snippets
meta	ElasticResultMeta	An object containing information about a given result

ElasticResultMeta

An object containing information about a given result.

Param	Type	Description
score	double	The relevance of the result

ElasticResultSnippet

An object contaning the snippet of the result. If you don't want to display your search results with highlights on the matching keyword, just ignore textParts and highlights and use only fullText.

textParts and highlights can be used to build a RichText widget in Flutter, please look at the example of the package to have a concrete example.

Param	Type	Description
fullText	String	The full snippet
textParts	List<String>	The snippet splitted in parts around the matched query
highlights	List<String>	The words matching the query

Third party packages

This app uses some external librairies:

• ✅ freezed to generate immutable models
• ✅ dio for http requests
• ✅ html_unescape to strip html tags from results

Roadmap for upcoming versions

• ✅ Support facets
• ✅ Support geo filters
• ❌ Support boosts
• ❌ Support nested filters
• ❌ Pass a converter to query to build response with your own objects from json response

Credits

This package was originally created for my personnal needs but feel free to use it, it does not covers all the features available in Elastic App Search, but I will try to cover all the features over time.

I am not related to Elastic in any way, I am just a developer who needed to use Elastic through a library, so I created this library to do so.

If you have questions, feel free to ask on Twitter.

LICENSE: MIT