138 lines
5.0 KiB
Markdown
138 lines
5.0 KiB
Markdown
# esquery
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**esquery** is a non-obtrusive, idiomatic and easy-to-use query and aggregation builder for the [official Go client](https://github.com/elastic/go-elasticsearch) for [ElasticSearch](https://www.elastic.co/products/elasticsearch). It alleviates the need to use extremely nested maps (`map[string]interface{}`) and serializing queries to JSON manually. It also helps eliminating common mistakes such as misspelling query types, as everything is statically typed.
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Save yourself some joint aches and many lines of code by switching for maps to `esquery`. Wanna know how much code you'll save? just read this project's test.
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## Usage
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esquery provides a [method chaining](https://en.wikipedia.org/wiki/Method_chaining)-style API for building and executing queries and aggregations. It does not wrap the official Go client nor does it require you to change your existing code in order to integrate the library. Queries can be directly built with `esquery`, and executed by passing an `*elasticsearch.Client` instance (with optional search parameters). Results are returned as-is from the official client (e.g. `*esapi.Response` objects).
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Getting started is extremely simple:
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```go
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package main
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import (
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"context"
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"log"
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"bitbucket.org/scalock/esquery"
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"github.com/elastic/go-elasticsearch/v7"
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)
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func main() {
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// connect to an ElasticSearch instance
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es, err := elasticsearch.NewDefaultClient()
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if err != nil {
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log.Fatalf("Failed creating client: %s", err)
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}
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// run a boolean search query
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qRes, err := esquery.Query(
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esquery.
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Bool().
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Must(esquery.Term("title", "Go and Stuff")).
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Filter(esquery.Term("tag", "tech")),
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).Run(
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es,
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es.Search.WithContext(context.TODO()),
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es.Search.WithIndex("test"),
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)
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if err != nil {
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log.Fatalf("Failed searching for stuff: %s", err)
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}
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defer qRes.Body.Close()
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// run an aggregation
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aRes, err := esquery.Aggregate(
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esquery.Avg("average_score", "score"),
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esquery.Max("max_score", "score"),
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).Run(
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es,
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es.Search.WithContext(context.TODO()),
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es.Search.WithIndex("test"),
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)
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if err != nil {
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log.Fatalf("Failed searching for stuff: %s", err)
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}
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defer aRes.Body.Close()
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// ...
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}
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```
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## Notes
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* `esquery` currently supports version 7 of the ElasticSearch Go client.
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* The library cannot currently generate "short queries". For example, whereas
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ElasticSearch can accept this:
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```json
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{ "query": { "term": { "user": "Kimchy" } } }
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```
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The library will always generate this:
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```json
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{ "query": { "term": { "user": { "value": "Kimchy" } } } }
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```
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This is also true for queries such as "bool", where fields like "must" can
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either receive one query object, or an array of query objects. `esquery` will
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generate an array even if there's only one query object.
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## Supported Queries
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The following queries are currently supported:
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| ElasticSearch DSL | `esquery` Function |
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| ------------------------|---------------------- |
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| `"match"` | `Match()` |
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| `"match_bool_prefix"` | `MatchBoolPrefix()` |
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| `"match_phrase"` | `MatchPhrase()` |
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| `"match_phrase_prefix"` | `MatchPhrasePrefix()` |
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| `"match_all"` | `MatchAll()` |
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| `"match_none"` | `MatchNone()` |
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| `"exists"` | `Exists()` |
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| `"fuzzy"` | `Fuzzy()` |
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| `"ids"` | `IDs()` |
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| `"prefix"` | `Prefix()` |
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| `"range"` | `Range()` |
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| `"regexp"` | `Regexp()` |
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| `"term"` | `Term()` |
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| `"terms"` | `Terms()` |
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| `"terms_set"` | `TermsSet()` |
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| `"wildcard"` | `Wildcard()` |
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| `"bool"` | `Bool()` |
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| `"boosting"` | `Boosting()` |
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| `"constant_score"` | `ConstantScore()` |
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| `"dis_max"` | `DisMax()` |
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### Custom Queries
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To execute an arbitrary query, or any query that is not natively supported by the library yet, use the `CustomQuery()` function, which accepts any `map[string]interface{}` value.
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## Supported Aggregations
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The following aggregations are currently supported:
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| ElasticSearch DSL | `esquery` Function |
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| ------------------------|---------------------- |
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| `"avg"` | `Avg()` |
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| `"weighted_avg"` | `WeightedAvg()` |
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| `"cardinality"` | `Cardinality()` |
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| `"max"` | `Max()` |
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| `"min"` | `Min()` |
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| `"sum"` | `Sum()` |
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| `"value_count"` | `ValueCount()` |
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| `"percentiles"` | `Percentiles()` |
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| `"stats"` | `Stats()` |
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| `"string_stats"` | `StringStats()` |
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### Custom Aggregations
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To execute an arbitrary aggregation, or any aggregation that is not natively supported by the library yet, use the `CustomAgg()` function, which accepts any `map[string]interface{}` value.
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