done

lib/python3.11/site-packages/dash/dcc/express.py

@@ -0,0 +1,106 @@
+import io
+import ntpath
+import base64
+
+# region Utils for Download component
+
+
+def send_file(path, filename=None, type=None):
+    """
+    Convert a file into the format expected by the Download component.
+    :param path: path to the file to be sent
+    :param filename: name of the file, if not provided the original filename is used
+    :param type: type of the file (optional, passed to Blob in the javascript layer)
+    :return: dict of file content (base64 encoded) and meta data used by the Download component
+    """
+    # If filename is not set, read it from the path.
+    if filename is None:
+        filename = ntpath.basename(path)
+    # Read the file contents and send it.
+    with open(path, "rb") as f:
+        return send_bytes(f.read(), filename, type)
+
+
+def send_bytes(src, filename, type=None, **kwargs):
+    """
+    Convert data written to BytesIO into the format expected by the Download component.
+    :param src: array of bytes or a writer that can write to BytesIO
+    :param filename: the name of the file
+    :param type: type of the file (optional, passed to Blob in the javascript layer)
+    :return: dict of data frame content (base64 encoded) and meta data used by the Download component
+    """
+    content = src if isinstance(src, bytes) else _io_to_str(io.BytesIO(), src, **kwargs)
+    return dict(
+        content=base64.b64encode(content).decode(),
+        filename=filename,
+        type=type,
+        base64=True,
+    )
+
+
+def send_string(src, filename, type=None, **kwargs):
+    """
+    Convert data written to StringIO into the format expected by the Download component.
+    :param src: a string or a writer that can write to StringIO
+    :param filename: the name of the file
+    :param type: type of the file (optional, passed to Blob in the javascript layer)
+    :return: dict of data frame content (NOT base64 encoded) and meta data used by the Download component
+    """
+    content = src if isinstance(src, str) else _io_to_str(io.StringIO(), src, **kwargs)
+    return dict(content=content, filename=filename, type=type, base64=False)
+
+
+def _io_to_str(data_io, writer, **kwargs):
+    # Some pandas writers try to close the IO, we do not want that.
+    data_io_close = data_io.close
+    data_io.close = lambda: None
+    # Write data content.
+    writer(data_io, **kwargs)
+    data_value = data_io.getvalue()
+    data_io_close()
+    return data_value
+
+
+def send_data_frame(writer, filename, type=None, **kwargs):
+    """
+    Convert data frame into the format expected by the Download component.
+    :param writer: a data frame writer
+    :param filename: the name of the file
+    :param type: type of the file (optional, passed to Blob in the javascript layer)
+    :return: dict of data frame content (base64 encoded) and meta data used by the Download component
+
+    Examples
+    --------
+
+    >>> df = pd.DataFrame({'a': [1, 2, 3, 4], 'b': [2, 1, 5, 6], 'c': ['x', 'x', 'y', 'y']})
+    ...
+    >>> send_data_frame(df.to_csv, "mydf.csv")  # download as csv
+    >>> send_data_frame(df.to_json, "mydf.json")  # download as json
+    >>> send_data_frame(df.to_excel, "mydf.xls", index=False) # download as excel
+    >>> send_data_frame(df.to_pickle, "mydf.pkl") # download as pickle
+
+    """
+    name = writer.__name__
+    # Check if the provided writer is known.
+    if name not in _data_frame_senders.keys():
+        raise ValueError(
+            "The provided writer ({}) is not supported, "
+            "try calling send_string or send_bytes directly.".format(name)
+        )
+    # Send data frame using the appropriate send function.
+    return _data_frame_senders[name](writer, filename, type, **kwargs)
+
+
+_data_frame_senders = {
+    "to_csv": send_string,
+    "to_json": send_string,
+    "to_html": send_string,
+    "to_excel": send_bytes,
+    "to_feather": send_bytes,
+    "to_parquet": send_bytes,
+    "to_msgpack": send_bytes,
+    "to_stata": send_bytes,
+    "to_pickle": send_bytes,
+}
+
+# endregion