The following examples show how to make HTTP requests using the HttpRequest class.
Simple Get Request
Make a Get request to a server and retrieve the status code, the response headers, and the response text body:
response = HttpRequest.Get('https://httpbin.org/')
print, response.status_code
print, response.headers
print, response.text
Get Request with Parameters
Here we send a couple of parameters to a server. Since our parameters contain disallowed characters (such as spaces) we use the ESCAPE keyword:
params = hash('param1', 'my value', 'param2', -123.4)
response = HttpRequest.Get('https://httpbin.org/', params=params, /escape)
print, response.url
IDL prints:
http://myserver.com/?param1=my%20value¶m2=-123.400
Tip: You can also use the HttpRequest.Escape and Unescape methods to convert strings with disallowed or special characters.
Get Request with Basic Authentication
Make a request using basic authentication:
basic = 'Basic ' + idl_base64(byte('myname:mypass'))
response = HTTPRequest.Get('myserver.org', headers=hash('Authorization', basic))
print, `status_code = ${response.status_code}`
Note: This is a fake URL so this example will not actually run; you will need to use your own URL and the correct username and password.
Handling Errors
Make a request to a nonexistent server. In this case you will get an internal CURL error (response code < 100) and the error message will be in the response.text field:
response = HTTPRequest.Get('http://myfancyserver.org')
print, `status_code = ${response.status_code}`
print, response.text
IDL prints:
status_code = 6
Could not resolve host: myfancyserver.org
Now make a request to a real server but a nonexistent path. In this case you will get a 404 response code and the server's response will be in the response.text field:
response = HTTPRequest.Get('http://google.com/mybadpath')
print, `status_code = ${response.status_code}`
print, response.text
IDL prints:
status_code = 404
<!DOCTYPE html>
<html lang=en>
...
<a href=//www.google.com/><span id=logo aria-label=Google></span></a>
<p><b>404.</b> <ins>That's an error.</ins>
<p>The requested URL <code>/mybadpath</code> was not found on this server. <ins>That's all we know.</ins>
Post Request with Key/Value Pairs
Make a post request, passing in two key/value pairs as parameters:
params = dictionary('key1', 'value1', 'key2', 'value2')
response = HTTPRequest.Post('https://httpbin.org/post', params=params)
print, `status_code = ${response.status_code}`
print, response.text
IDL prints:
status_code = 200
{
...
"form": {
"key1": "value1",
"key2": "value2"
},
"headers": {
"Accept": "*/*",
"Content-Length": "23",
"Content-Type": "application/x-www-form-urlencoded",
...
},
...
}
Post Request with JSON Data
Make a post request and pass in two key/value pairs as JSON data. The response body is in JSON format so we use the HttpRequest.Json method:
formdata = dictionary('key1', 'value1', 'key2', 'value2')
response = HTTPRequest.Post('https://httpbin.org/post', json=formdata)
print, response.json(), /implied
IDL prints:
{
"data": "{\"key2\":\"value2\",\"key1\":\"value1\"}",
"headers": {
"Accept": "*/*",
"Content-Length": "33",
"Content-Type": "application/json",
...
},
"json": {
"key1": "value1",
"key2": "value2"
},
...
}
Post Request with Multipart Form and Files
Make a post request with a multipart form that includes a simple string, some binary data (with and without a mime type), and two files (one with a mime type):
myfile = filepath('md1107g8a.jpg', subdir=['examples', 'data'])
myformdata = dictionary('name', 'Dave Stern', $
'mydata1', bindgen(10), $
'mydata2', {value: bindgen(10), mimetype: 'application/octet-stream'}, $
'myimage1', {file: myfile}, $
'myimage1', {file: myfile, mimetype: 'image/jpeg'})
response = HTTPRequest.Post('https://myserver.org/', multipart=myformdata)
Note: This is a fake URL so this example will not actually run; it is only here to show how to pass multipart data.
Get Request with a Callback
First we define a callback function that will print out a progress status. Our callback also looks for a keypress: if you press "q" then the function will return zero and the request will be canceled.
function mycallback, downTotal, downNow, upTotal, upNow, callbackData
compile_opt idl2
if (get_kbrd(0) eq 'q') then return, 0
percent = round(100 * float(downNow) / (downTotal > 1))
if (callbackData eq percent) then return, 1
callbackData = percent
if (percent gt 0) then print, `${percent}% ${('*').dup(stars)}`
return, 1
end
Now download a large file, making sure to pass in our callback function and our initial percentage:
response = HTTPRequest.Get('http://mattmahoney.net/dc/enwik8.zip', $
CALLBACK_FUNCTION='mycallback', CALLBACK_DATA=0)
IDL prints:
1% *
...
50% **************************************************
...
100% ****************************************************************************************************
Version History
See Also
HttpRequest