PluginSettings.get_plugin_data_folder moved to OctoPrintPlugin.get_plugin_data_folder

That way plugins don't need to implement the SettingsPlugin mixin in order to access their data folder, which is now an injected property in OctoPrintPlugin. Plugin authors should still always use the getter since that will also make sure the folder actually does exist (lazy creation).

PluginSettings.get_plugin_data_folder has been marked as deprecated.

docs/plugins/concepts.rst

@@ -257,7 +257,7 @@ them as (hopefully) documented.
    :emphasize-lines: 6-8,20
    :caption: Excerpt from the Growl Plugin showing utilization of the helpers published by the Discovery Plugin.
    :name: sec-plugin-concepts-helpers-example-usage
-   
+
    def on_after_startup(self):
        host = self._settings.get(["hostname"])
        port = self._settings.getInt(["port"])
@@ -270,7 +270,7 @@ them as (hopefully) documented.
        self.growl, _ = self._register_growl(host, port, password=password)
 
    # ...
-   
+
    def on_api_get(self, request):
        if not self.zeroconf_browse:
            return flask.jsonify(dict(
@@ -302,6 +302,10 @@ An overview of these properties follows.
 ``self._basefolder``
   The plugin's base folder where it's installed. Can be used to refer to files relative to the plugin's installation
   location, e.g. included scripts, templates or assets.
+``self._datafolder``
+  The plugin's additional data folder path. Can be used to store additional files needed for the plugin's operation (cache,
+  data files etc). Plugins should not access this property directly but instead utilize :func:`~octoprint.plugin.types.OctoPrintPlugin.get_plugin_data_folder`
+  which will make sure the path actually does exist and if not create it before returning it.
 ``self._logger``
   A `python logger instance <https://docs.python.org/2/library/logging.html>`_ logging to the log target
   ``octoprint.plugin.<plugin identifier>``.
@@ -340,4 +344,4 @@ Lifecycle
 
 .. image:: ../images/plugins_lifecycle.png
    :align: center
-   :alt: The lifecycle of OctoPrint plugins.
+   :alt: The lifecycle of OctoPrint plugins.

src/octoprint/plugin/__init__.py

@@ -426,12 +426,10 @@ class PluginSettings(object):
 		filename += ".log"
 		return os.path.join(self.settings.getBaseFolder("logs"), filename)
 
+	@deprecated("PluginSettings.get_plugin_data_folder has been replaced by OctoPrintPlugin.get_plugin_data_folder",
+	            includedoc="Replaced by :func:`~octoprint.plugin.types.OctoPrintPlugin.get_plugin_data_folder`",
+	            since="1.2.0")
 	def get_plugin_data_folder(self):
-		"""
-		Retrieves the path to a data folder specifically for the plugin.
-
-		Plugins may use this for storing additional data.
-		"""
 		path = os.path.join(self.settings.getBaseFolder("data"), self.plugin_key)
 		if not os.path.isdir(path):
 			os.makedirs(path)

src/octoprint/plugin/types.py

@@ -69,9 +69,32 @@ class OctoPrintPlugin(Plugin):
 
 	   The :class:`~octoprint.server.LifecycleManager` instance. Injected by the plugin core system upon initialization
 	   of the implementation.
+
+	.. attribute:: _data_folder
+
+	   Path to the data folder for the plugin to use for any data it might have to persist. Should always be accessed
+	   through :meth:`get_plugin_data_folder` since that function will also ensure that the data folder actually exists
+	   and if not creating it before returning it. Injected by the plugin core system upon initialization of the
+	   implementation.
+
+    .. automethod:: get_plugin_data_folder
 	"""
 
-	pass
+	def get_plugin_data_folder(self):
+		"""
+		Retrieves the path to a data folder specifically for the plugin, ensuring it exists and if not creating it
+		before returning it.
+
+		Plugins may use this folder for storing additional data they need for their operation.
+		"""
+		if self._data_folder is None:
+			raise RuntimeError("self._plugin_data_folder is None, has the plugin been initialized yet?")
+
+		import os
+		if not os.path.isdir(self._data_folder):
+			os.makedirs(self._data_folder)
+		return self._data_folder
+
 
 class ReloadNeedingPlugin(Plugin):
 	pass

src/octoprint/server/__init__.py

@@ -196,7 +196,8 @@ class Server():
 				file_manager=fileManager,
 				printer=printer,
 				app_session_manager=appSessionManager,
-				plugin_lifecycle_manager=pluginLifecycleManager
+				plugin_lifecycle_manager=pluginLifecycleManager,
+				data_folder=os.path.join(settings().getBaseFolder("data"), name)
 			)
 
 		def settings_plugin_inject_factory(name, implementation):