Operate ElasticSearch with HTTP Methods

1. Index

1.1 Create Index

Creating an index in ElasticSearch is like creating a database in a relational database.
First we open postman to send the request.

http://127.0.0.1:9200/shopping

If you get this response, it has been successfully created.

1.2 View Index

To view the shopping index, the command remains the same, except that you have to change the request method to a GET request.

1.3 View All Indexes

Send GET request:

http://127.0.0.1:9200/_cat/indices?v

Since we have only created one index, shopping, only one index will be displayed.

where the meaning of the table header:

Header	Meaning
health	Current server health status. Green–Clusters are complete; Yellow–Single point is normal, but cluster is incomplete; Red–Single point server not working properly.
status	Index open, closed status
index	Index name
uuid	Uniform index number
pri	Number of master splits
rep	Number of replicas
docs.count	Number of availiable documents
docs.deleted	Document deletion status (logic deletion)
store.size	Size of the overall space occupied by the master and slave splits
pri.store.size	Size of the primary split

1.4 Delete Index

The path remains the same and change the request method to DELETE to remove the shopping index.

2. Document Operation

2.1 Create Document

To create documents, you need to use POST requests. Why is this different from creating indexes? Because creating a document generates a random id each time, and the id is different each time, whereas PUT requests are idempotent, so you can’t use PUT requests.

http://127.0.0.1:9200/shopping/_doc
OR
http://127.0.0.1:9200/shopping/_created

request body:

{
    "title":"Apple", 
    "category":"Mobile Phone", 
    "images":"http://www.gulixueyuan.com/apple.jpg", 
    "price":1999.00 
}

Sometimes it is very inconvenient to use automatically generated ids. So when creating it, we can customize the id for it.

http://127.0.0.1:9200/shopping/_doc/1001

If this works, the id will be the same each time, so we can also use a PUT request.

2.2 Query Document

The command remains the same, just change it to a GET request.

2.3 Update Document

http://127.0.0.1:9200/shopping/_update/1001

request body:

{
    "doc":{
        "price":3000.00
    }
}

2.4 Delete Document

The command is the same as Create Document and just change the request method to DELETE.

3. Query

3.1 Full Query

GET request

http://127.0.0.1:9200/shopping/_search

3.2 Conditional Query

http://127.0.0.1:9200/shopping/_search?q=Apple

http://127.0.0.1:9200/shopping/_search?q=title:Apple

conditions followed after q
Or, you can put condition in the request body.

{
    "query":{
        "match":{
            "title":"Apple"
        }
    }
}

3.3 Paged Query

{
    "query":{
        "match_all":{
 
        }
    },
    "from":0,
    "size":2
}

from means starting from which page and size means how many pages of data are displayed.

3.4 Multi-Condition Query

{
	"query" : {
		"bool" : {
			"must" : [
				{
					"match" : {
						"title":"Apple"
					}
				},
				{
					"match" : {
						"price":1999.00
					}
				}
			]
		}
	}
}

Must will seek for data where all conditions are met (equivalent to AND).
If you change must to should, you will find data that satisfies one or more conditions (equivalent to OR).