REST API with cURL | Nam Hoai Nguyen

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Official Docs

In Postman we can click on Code Snippet to show the cURL command (and other command
too).

General

Note that, -X = --request

1curl -X [method] [options] [URL]

The most important options/flags

1-B: Use ASCII for text and transfer.
2-C: Resume an interrupted transfer.
3-d: Data for the HTTP POST or PUT commands.
4-E: Use a client certificate file and optional password.
5-F: Update a HTTP form request from a file.
6-H: Pass a custom header to the server.
7-K: Use a file for the configuration.
8-m: Set a maximum time for the transfer.
9-N: Disable buffering.
10-o: Write the output to a file.
11-s: Run in silent mode.
12-u: Add a user name and password for the server.
13-v: Verbose mode, for more details.
14-X: Specifies the HTTP command to use.
15-4: Use Ipv4 addresses.
16-6: Use Ipv6 addresses.
17-#: Display a progress bar. This is useful for large transfers.

cURL in PHP

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We need to install extensions php-curl to use it. Checkthe
Official Documentation to learn more

Send Request

Init cURL

1// create & initialize a curl session
2$curl = curl_init();
3
4/**
5* Some code
6**/
7
8// close curl resource to free up system resources
9// (deletes the variable made by curl_init)
10curl_close($curl);

GET method

1curl_setopt($curl, CURLOPT_URL, '<https://api.github.com/events>');
2# request header
3curl_setopt($curl, CURLOPT_HTTPHEADER, array(
4  'Content-Type: application/json',
5  'User-Agent: cURL'
6));
7$raw = curl_exec($curl);

POST method

1curl_setopt($curl, CURLOPT_URL, '<https://httpbin.org/post>');
2curl_setopt($curl, CURLOPT_POST, 1);
3# request header
4curl_setopt($curl, CURLOPT_HTTPHEADER, array(
5  'Content-Type: application/json'
6));
7curl_setopt($curl, CURLOPT_POSTFIELDS, '{"key": "value"}');
8$raw = curl_exec($curl);

Response

Body response

1// Raw text
2...
3$raw = curl_exec($curl);
4
5# JSON
6json_decode($raw, true);

Status code ???

1$statusCode = curl_getinfo($curl, CURLINFO_HTTP_CODE); // $statusCode = 200

Some examples

GET

1curl -X GET '<http://abc:3000/xyz/enpoint?paramOne=1&paramTwo=2>' \
2 --header 'clientEmail: abc@xyz.com' \
3 --header 'privateKey: XXXX'
4 }'

POST

The JSON data must be in the form of '{with the "double quotes" inside}'. This "{single 'quote' inside}" will not
work!

1curl -X POST '<http://abc:3000/xyz/enpoint?paramOne=1&paramTwo=2>' \
2 --header 'clientEmail: abc@xyz.com' \
3 --header 'privateKey: LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCk1JSUV2Z0lCQU' \
4 --header 'Content-Type: application/json' \
5 --data-raw '{
6  "dataMain": {
7   "keyOne": "valueOne",
8   "keyTwo": 2
9  }
10 }'

or with JSON file

1curl -X POST \
2  --header "Content-Type: application/json" \
3  --data @.folder/file.json \
4  <http://localhost:8080/ui/webapp/conf>

or form data

We have a form that can upload file

1<form method="POST" enctype="multipart/form-data" action="upload.cgi">
2  <input type="file" name="upload" />
3  <input type="submit" name="press" value="OK" />
4</form>

1curl --form upload=@/home/user/Pictures/wallpaper.jpg --form press=OK [URL]