Nourishing Plushie Monster

    esql

    0.0.4 • Public • Published

    ESQL (Elasticsearch Query Language)

    Elasticsearch is powerful, so is its Query DSL. But Elasticsearch Query DSL's power comes at a cost: complexity. Even the simplest queries can be verbose and difficult to write. ESQL simplifies the construction of Query DSL by compiling queries written in an SQL-like language to Elasticsearch DSL. By only supporting essential features of the Query DSL, ESQL queries can be kept very simple.

    The output of ESQL can be used directly as the search argument of elasticsearch-js. However, you may pick different portions should you use another mechanism to connect to Elasticsearch. You can also augment the output however you like. Therefore, you are not locked in to only the features supported by ESQL.

    ESQL can be used in both Node and browser environments.

    Features

    • Scope: specify indices, types and options
    • Filter: term, terms, range
    • Query: match, multi_match, range
    • Filter/query group: must, should, must_not
    • Sort: sort, asc, desc
    • Data types: boolean, number, string/date, array, null
    • Options can be specified at each level of granularity
    • Query parameterization and precompilation
    • More to come...

    Note: this is an early release of ESQL, expect the language itself and possibly the API to change. Oh yes, and bugs too. Bug reports and pull requests are very welcome.

    Getting started

    Install ESQL from NPM or Bower

    npm install --save esql
    
    bower install --save esql
    

    Import esql object in Node

    var esql = require('esql')

    Import esql object in browser (after referencing browser/esql.min.js)

    var esql = window.esql

    Build DSL query

    var query = 'ESQL QUERY HERE'
    var dsl = esql(query)

    Parameterize queries

    var dsl = esql('match name = $1, age = $2', name, age)

    Precompile queries

    var fn = esql.prepare('match name = $1, age = $2')
    var dsl = fn(name, age)

    Consume DSL query with elasticsearch-js

    var client = new es.Client({...})
    client.search(dsl).then(callback, errback)

    Example

    var dsl = esql(
      'from org / documents with ("from": 20, size: 10) \
       filter expired == false, level == 3..5 \
       match name = "foo" (boost: 2), description = "foo bar" (operator: "and") with (minimum_should_match: 1) \
       sort name asc, description')

    The resulting dsl object is:

    {
      "body": {
        "query": {
          "filtered": {
            "filter": {
              "bool": {
                "must": [
                  {
                    "term": {
                      "expired": false
                    }
                  },
                  {
                    "range": {
                      "level": {
                        "gte": 3,
                        "lte": 5
                      }
                    }
                  }
                ]
              }
            },
            "query": {
              "bool": {
                "minimum_should_match": 1,
                "should": [
                  {
                    "match": {
                      "name": {
                        "boost": 2,
                        "query": "foo"
                      }
                    }
                  },
                  {
                    "match": {
                      "description": {
                        "operator": "and",
                        "query": "foo bar"
                      }
                    }
                  }
                ]
              }
            }
          }
        },
        "sort": [
          {
            "name": {
              "order": "asc"
            }
          },
          {
            "description": {
              "order": null
            }
          }
        ]
      },
      "index": "org",
      "type": "documents",
      "from": 20,
      "size": 10
    }

    The dsl object can be fed directly to elasticsearch-js. Or you can just use its body property as POST data for your own Elasticsearch query mechanism.

    Syntax Reference

    Basics

    ESQL is case insensitive. Spaces and newlines are skipped so you can have as many of them. All clauses are optional although if specified, they must follow this order: from, filter, query, sort.

    Filter/query groups are made possible with these mappings:

    • = is mapped to should
    • == is mapped to must
    • != is mapped to must_not

    Range filters and queries are supported with range syntax:

    • from..to => from from to to inclusively
    • from...to => from from to to exclusively
    • Either from or to can be optional

    Options can be specified for each filter, match, sort condition or the entire group. Option names and values are not type-checked or validated in anyway whatsoever. This makes the language simple and flexible but requires you to learn about the available options.

    FROM clause

    Use the from clause to specify indices, types and general query options.

    Example 1: index only

    from index1
    

    Example 2: index and type

    from index1 / type1
    

    Example 3: multiple indices and types (including wildcard match)

    from [index1, index2] / [type1, type2, moretype*]
    

    Example 4: query options, note that from option needs escaping

    from index / type with ('from': 10, size: 100)
    

    FILTER clause

    Use the filter clause to create filters.

    Example 1: term search

    filter tags = 'foo'
    

    Example 2: terms search

    filter tags = ['foo', 'bar']
    

    Example 3: multiple filters

    filter tags = 'foo', expired = false
    

    MATCH clause

    Use the match clause to create queries.

    Example 1: single match

    match name = 'foo' // => match
    

    Example 2: multi-match

    match [name, description] = 'foo' // => multi_match
    

    Example 3: multiple matches with options

    match name = 'foo' (boost: 2), description = 'foo bar' (minimum_should_match: 1)
    

    SORT clause

    Use the sort clause to specify sort fields and directions

    Example

    sort name asc, age desc
    

    Install

    npm i esql

    DownloadsWeekly Downloads

    5

    Version

    0.0.4

    License

    MIT

    Last publish

    Collaborators

    • buunguyen