Box Developer Documentation
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Preflight check before upload

options
https://api.box.com/2.0
/files/content

Performs a check to verify that a file will be accepted by Box before you upload the entire file.

Related Guides

Request

bearer [ACCESS_TOKEN]
application/json

Request Body

stringin bodyoptional
"File.mp4"

The name for the file

objectin body

The parent folder to upload the file to

stringin bodyoptional
"123"

The ID of parent item

stringin bodyoptional
"12346930"

The input for {user_id} is optional. Moving to non-root folder is not allowed when {user_id} is present. Parent folder id should be zero when {user_id} is provided.

integer (int32)in bodyoptional
1024

The size of the file in bytes

Response

application/jsonUpload URL

If the check passed, the response will include a session URL that can be used to upload the file to.

application/jsonConflict error

If the check did not pass, the response will include some details on why it did not pass.

application/jsonClient error

An unexpected client error.

options
Preflight check before upload
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Request Example

cURL
curl -i -X OPTIONS "https://api.box.com/2.0/files/content" \
     -H "authorization: Bearer <ACCESS_TOKEN>" \
     -H "content-type: application/json" \
     -d '{"name":"Contract.pdf", "parent":{"id":"11446498"}}'
Java
String fileName = "My Doc.pdf";
BoxFolder rootFolder = BoxFolder.getRootFolder(api);
try {
    folder.canUpload(fileName, 98734576);

    // If the file upload would not have succeeded, it will not be attempted
    folder.uploadFile(fileContents, fileName);
} catch (BoxAPIException ex) (

)
Node
// Verify that uploading a 200MB file named "Preso.ppt" to folder 12345 would succeed
client.files.preflightUploadFile(
		'12345',
		{
			name: 'Preso.ppt',
			size: 200000000
		},
		null,
		callback
	);

Response Example

{
  "upload_token": "Pc3FIOG9vSGV4VHo4QzAyg5T1JvNnJoZ3ExaVNyQWw6WjRsanRKZG5lQk9qUE1BVQP",
  "upload_url": "https://upload-las.app.box.com/api/2.0/files/content?upload_session_id=1234"
}