form:AddFile -- add file upload section to a multipart/formdata HTTP POST
form:AddFile(name, path[, type, filename, headers])
form:AddFile() is used to append a file upload section when building a multipart/formdata HTTP POST (sometimes referred to as RFC 2388-style posts). Once you've added all the sections you want included, pass the form handle as parameter to #CURLOPT_HTTPPOST. See easy:SetOpt_HTTPPost for details.

You must call form:Free() after the form post has been done to free the resources.

Using POST with HTTP 1.1 implies the use of a "Expect: 100-continue" header. You can disable this header with #CURLOPT_HTTPHEADER as usual.

First, there are some basics you need to understand about multipart/formdata posts. Each part consists of at least a NAME and a CONTENTS part. If the part is made for file upload, there are also a stored CONTENT-TYPE and a FILENAME. Below, we'll discuss what options you use to set these properties in the parts you want to add to your post.

The name argument must be a string which provides the name of this part. The name is not allowed to contain zero-valued bytes.

The path argument must be set to the path of a filename to be uploaded. Libcurl sets the filename field to the basename of the provided filename, it reads the contents of the file and passes them as data and sets the content-type if the given file match one of the internally known file extensions. The given upload file has to exist in its full in the file system already when the upload starts, as libcurl needs to read the correct file size beforehand. The specified file needs to kept around until the associated transfer is done.

The optional argument type can be used to set the content-type for the part. The optional filename argument can be used to use a different file name than the one derived from path for the upload. The optional argument headers can be used to specify extra headers for the form POST section. This takes a table containing a list and appends the list of headers to those libcurl automatically generates.

name of the part
path to a file to upload
optional: content-type for the part
optional: filename for the content header
optional: extra headers for the POST section

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