CRUD API

APIs

Read

eldeim@htb[/htb]$ curl http://<SERVER_IP>:<PORT>/api.php/city/london

[{"city_name":"London","country_name":"(UK)"}]

We can pipe the output to the jq utility, which will format it properly. We will also silent any unneeded cURL output with -s, as follows:

eldeim@htb[/htb]$ curl -s http://<SERVER_IP>:<PORT>/api.php/city/london | jq

[
  {
    "city_name": "London",
    "country_name": "(UK)"
  }
]

Create

We can simply POST our JSON data, and it will be added to the table. As this API is using JSON data, we will also set the Content-Type header to JSON, as follows:

eldeim@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'

Now, we can read the content of the city we added (HTB_City), to see if it was successfully added:

eldeim@htb[/htb]$ curl -s http://<SERVER_IP>:<PORT>/api.php/city/HTB_City | jq

[
  {
    "city_name": "HTB_City",
    "country_name": "HTB"
  }
]

Update

Using PUT is quite similar to POST in this case, with the only difference being that we have to specify the name of the entity we want to edit in the URL, otherwise the API will not know which entity to edit. So, all we have to do is specify the city name in the URL, change the request method to PUT, and provide the JSON data like we did with POST, as follows:

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

Note: In some APIs, the Update operation may be used to create new entries as well. Basically, we would send our data, and if it does not exist, it would create it. For example, in the above example, even if an entry with a london city did not exist, it would create a new entry with the details we passed. In our example, however, this is not the case. Try to update a non-existing city and see what you would get.

Delete

We simply specify the city name for the API and use the HTTP DELETE method, and it would delete the entry, as follows:

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

eldeim@htb[/htb]$ curl -s http://<SERVER_IP>:<PORT>/api.php/city/New_HTB_City | jq
[]

As we can see, after we deleted New_HTB_City, we get an empty array when we try reading it, meaning it no longer exists.