A Basic CRUD Application Using ElasticSearch

In our previous post Introduction To ElasticSearch, we talked about the basic terminology of elastic search and basic requests to create or delete an index, check the health status of the cluster, indices etc.

In this post, we are going to talk about creating a basic CRUD application using DSL. Without waiting let’s get started. To create an application, first, create an SBT Project, add elastic search dependency in build.sbt.

"org.elasticsearch" % "elasticsearch" % "6.2.4"

The Project has been set up. Next, we need a client which will talk to the elastic search server. There are various clients i.e rest high-level client, transport client etc. We will be using Java High-Level Rest Client as it is light weight. To use it we have to add the following dependency for it.

"org.elasticsearch.client" % "elasticsearch-rest-high-level-client" % "6.1.2"

Let’s create a client

private val port = 9200
private val host = "localhost"
private val scheme = "http"

val client = new RestHighLevelClient(
RestClient.builder(new HttpHost(host, port, scheme))
)

Now we have a client and can easily query the Elastic search server. Let’s create the first document of the books in the library.

val jsonString = {
"id": 1,
"author": "Paulo Coelho",
"title": "The Alchemist",
"language": "en",
"yearOfPublishing": 1988,
"genre":"Adventure Fiction"
}

Let’s index this document to elastic search

val indexRequest = new IndexRequest("indexName", "typeName", "id")
indexRequest.source(jsonString, XContentType.JSON)
client.index(indexRequest)

To delete the document by an id

val deleteRequest = new DeleteRequest("indexName", "typeName", 1)
client.delete(deleteRequest)

To update any document.

val updateRequest = new UpdateRequest("indexName", "typeName", id)
val builder = XContentFactory.jsonBuilder

builder.startObject()
builder.field(fieldName, value)
builder.endObject()

updateRequest.doc(builder)
client.update(updateRequest)

To search the document by field. Let’s say title name

val searchRequest = new SearchRequest("indexName")
val searchSourceBuilder = new SearchSourceBuilder

searchSourceBuilder.query(QueryBuilders.matchPhraseQuery("title", "The Alchemist"))
searchRequest.source(searchSourceBuilder)

client.search(searchRequest)

We are done with basic crud operations. We will see bulk requests, term query or different ways of query in ES and how we can tune our searching. For full code get it from here

Hope it will help. Please feel free to suggest or comment.

References:

Elastic Search Documentation