@hikeland https://dart.dev/ https://flutter.dev/

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

Elastic

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

App preview

Table of contents

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:

Roadmap for upcoming versions

  • x Support facets
  • x 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

Libraries