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36 ” cURL Extension Simple R equest and R esponse H andling Let’s look at this line by line. • curl_init is called and passed ’http://localhost.example/path/to/form’ as the URL for the request. N ote this parameter is optional and can also be specified by calling curl_setopt with the cURL session handle ($ch in this case), the CURLOPT_URL constant, and the URL string. • curl_setopt is called to set the configuration setting represented by the CURLOPT_RETURNTRANSFER parameter to have a value of true. This setting will cause curl_exec to return the HTTP response body in a string rather than outputting it directly, the latter being the default behavior. • curl_exec is called to have it execute the request and return the response body. • curl_close is called to explicitly close the cURL session handle, which will no longer be reusable after that point. A useful setting worth mentioning early on is CURLOPT_VERBOSE, which outputs debugging information when set to true. This output is sent to either stderr (the default) or the file referenced by the value of the CURLOPT_STDERR. Contrasting GET and POST Ob viously the cURL extension has other functions, but by and large most HTTP requests made using the cURL extension will follo w the sequence of operations sho wn in the abo ve example. Let’s compare this with a POST request.
cURL Extension ” 37 $data = array( ’param1’ => ’value1’, ’param2’ => ’value2’, ’file1’ => ’@/path/to/file’, ’file2’ => ’@/path/to/other/file’ ); $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, ’http://localhost.example/process’); curl_setopt($ch, CURLOPT_POST, true); curl_setopt($ch, CURLOPT_POSTFIELDS, $data); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); $response = curl_exec($ch); curl_close($ch); ?> H ere are the differences between this example and the previous one. • The URL is passed using the curl_setopt function this time, just to sho w ho w to do it without passing it to the curl_init function. This is important when reusing cURL session handles with different URLs. • CURLOPT_POST is set to true to change the request method to POST. • CURLOPT_POSTFIELDS is an associative array or preformatted query string to be used as the data for the request body. Files can be uploaded by specifying a value where the first character is @ and the remainder of the value is a filesystem path to the file intended for upload. H ere are a few other cURL configuration setting constants related to the request method. • CURLOPT_HTTPGET: Boolean that, when set to true, explicitly resets the request method to GET if it’s been changed from the default. • CURLOPT_NOBODY: Boolean that, when set to true, excludes the body from the response by changing the request method to HEAD .
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