Elasticsearch from 0 to sky: CRUD- Chapter 2

JSON Objects

Elasticsearch works with data structures represented as JSON objects.

• JSON documents are saved with a unique ID
• In Elasticsearch the documents are indexed in index

{
 "title": "Elasticsearch from 0 to sky: CRUD",
 "tecnology": "Elasticsearch",
 "date": "23/02/2021",  
 "author": {  
    "first_name": "Ivan",
    "last_name": "Frias",
    "company": "CIVIR"
 }
}

Indexing documents

Index API is used to index documents, we can use a curl.
It is necessary to indicate the name of the index (1), endpoint (2) and the ID (3)
The ID can be autogenerated if not specified.

                                      (1)    (2) (3)
$ curl -X PUT "elasticsearch:9200/name_index/_doc/1" -H 'Content-Type: application/json' -d'
{
 "title": "Elasticsearch from 0 to sky: CRUD",
 "tecnology": "Elasticsearch",
 "date": "23/02/2021",  
 "author": {  
    "first_name": "Ivan",
    "last_name": "Frias",
    "company": "CIVIR"
 }
}

An index called “name_index” with an ID “1” will be created

• Kibana now incorporates a console where you can make requests much more visual, we can also use Postman or any other program.
• The indexes will be created automatically when you index a document.

The indexes can be created manually in the following way:

$ curl -X PUT "elasticsearch:9200/name_index"
{ 
  "settings":{
  },
  "mappings":
  {
  } 
}

- Add doc with ID 1

PUT index

To read the indexed documents, it is necessary to specify the index and the ID of the document.

GET name_index/_doc/1

GET index

Endpoints

There are different endpoints to perform CRUD operations (Create, Read, Update, Delete).

• _create

Use _create to create documents, if the ID exists it will give a 409 error, otherwise you use endpoint (as in the previous example) it will be created and updated when you use the same ID (index).

create doc

ID already exists

• _update

Use _update to update documents, the _version field will increment.

• delete

Use delete to delete a document, response code is 200 when the document has been found and deleted.

Bulk API

• _bulk

It allows to carry out many operations with a single call, optimizing the result with an increase in speed.
Allows create, index, update and delete actions.

• _mget

Allows to return multiple documents by ID (multi get)