M3-CRUD API

APIs

There are several types of APIs.

APIs are used to interact with a database, so that we can specify the requested table and requested row within our API query, and then use HTTP method to perform the operation needed.

Let’s say there is api.php and we want to update the city table in the database, and the row we will be updating has a city name of seoul, then the URL would look something like this:

curl -X PUT http://<SERVER_IP>:<PORT>/api.php/city/london ...SNIP...

CRUD

In general, APIs perform 4 main operations on the requested database entity:

Operation	HTTP Method	Description
`Create`	`POST`	Adds the specified data to the database table
`Read`	`GET`	Reads the specified entity from the database table
`Update`	`PUT`	Updates the data of the specified database table
`Delete`	`DELETE`	Removes the specified row from the database table

Above four operations are mainly linked to CRUD APIs, but the same principal is used in REST APIs as well.

Obviously, not all APIs work in the same way and user access control limits what actions we can perform and what results we can see.

Read

We can interact with an API to read data as such:

jadu101@htb[/htb]$ curl http://<SERVER_IP>:<PORT>/api.php/city/london
 
[{"city_name":"London","country_name":"(UK)"}]

To have the json result properly formatted in JSON, we can use jq utility:

jadu101@htb[/htb]$ curl -s http://<SERVER_IP>:<PORT>/api.php/city/london | jq
 
[
  {
    "city_name": "London",
    "country_name": "(UK)"
  }
]

Create

We can use HTTP POST to add a new entry.

jadu101@htb[/htb]$ curl -X POST http://<SERVER_IP>:<PORT>/api.php/city/ -d '{"city_name":"HTB_City", "country_name":"HTB"}' -H 'Content-Type: application/json'

Update

PUT is used to update API entries and modify their details. It similar to POST but it is different that we have to specify the name of the entity we want to edit in the URL.

DELETE is used to remove a specific entity.

jadu101@htb[/htb]$ curl -X PUT http://<SERVER_IP>:<PORT>/api.php/city/london -d '{"city_name":"New_HTB_City", "country_name":"HTB"}' -H 'Content-Type: application/json'

Above command replaces london with New_HTB_City.

DELETE

DELETE is used to delete the entry.

jadu101@htb[/htb]$ curl -X DELETE http://<SERVER_IP>:<PORT>/api.php/city/New_HTB_City

👨‍💻👾👨‍💻👾👨‍💻👾

Explorer