Responses

Here, let's take a look into how responses are built in Frappe, and how you may be able to use them in your Frappe apps or scripts.

If you have already gone through the Router Documentation, you might've noticed the build_response function that Frappe internally utilizes to build responses depending on the type of the content. The logic that defines this behaviour is a part of the module frappe.utils.response, of which build_response is the meat and potatoes.

def build_response(response_type=None):
  if "docs" in frappe.local.response and not frappe.local.response.docs:
    del frappe.local.response["docs"]

  response_type_map = {
    "csv": as_csv,
    "txt": as_txt,
    "download": as_raw,
    "json": as_json,
    "pdf": as_pdf,
    "page": as_page,
    "redirect": redirect,
    "binary": as_binary,
  }

  return response_type_map[frappe.response.get("type") or response_type]()

The above snippet represents the current implementation of build_response which maps different functions that act as handlers for different content types. Let's take a deeper look into the response handler for the "download" response_type in Frappe v13.

def as_raw():
  response = Response()
  response.mimetype = (
    frappe.response.get("content_type")
    or mimetypes.guess_type(frappe.response["filename"])[0]
    or "application/unknown"
  )
  response.headers["Content-Disposition"] = (
    f'{frappe.response.get("display_content_as", "attachment")};'
    f' filename="{frappe.response["filename"].replace(" ", "_")}"'
  ).encode("utf-8")
  response.data = frappe.response["filecontent"]
  return response

Depending on the value of the Content-Disposition header, the browser receiving the response may behave differently. If unset, the value defaults to "attachment".

If frappe.response.display_content_as is set to "inline", it indicates that the content is expected to be displayed inline in the browser, that is, as a Web page or as part of a Web page, while "attachment" means the contents are to be downloaded and saved locally.

To create an API endpoint that would directly download the file you require, you could craft something like the following to download the file directly.

@frappe.whitelist()
def download(name):
  file = frappe.get_doc("File", name)
  frappe.response.filename = file.file_name
  frappe.response.filecontent = file.get_content()
  frappe.response.type = "download"
  frappe.response.display_content_as = "attachment"
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